essay on nutrition in animals

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Nutrition Animals

Nutrition In Animals: How Animals Eat Their Food?

Table of contents, introduction, nutrition in animals, types of nutrition in animals, process of nutrition in animals, nutrition in simple animals.

Nutrition in animals is as important as it is for plants. Plants prepare their own food by the process of photosynthesis but animals cannot prepare their own food, hence they need to depend on plants or other animals for their food.

Animals derive their nutrition either by eating plants directly (herbivores), or indirectly by eating animals which have consumed plants (carnivores). Some animals feed on both plants and animals; these animals are termed omnivores. All organisms require food for their survival and growth.

Food has different components, called nutrients, like carbohydrates, fats, minerals, proteins, and vitamins, which are required for the maintenance of the body. These components are complex and cannot be used directly, so they are broken down into simpler components by the process of digestion.

Also Read: Nutrition in Living Organisms

Nutrition in animals depends upon the feeding habits of the animals. The process of taking in food is called ingestion. The method of ingestion is different in different animals. For example-Bees and hummingbirds suck nectar from plants, a python swallows its prey and cattle feed on grass.

Different feeding habits of animals are the result of evolution . Among the terrestrial animals, the earliest forms were large amphibians that ate fish. While amphibians like frogs fed on small fish and insects, the reptiles began feeding on other animals and plants.

The specialization of organisms towards specific food sources and of course specific ways of eating is one of the major causes of the evolution of form and function. For example, the differences in the parts of the mouth and shape of the teeth in whales, mosquitos, tigers and sharks or distinct forms of beaks in birds, such as in hawks, woodpeckers, pelicans, hummingbirds, and parrots are the results of adaptation to different types of eating by these animals.

Animals can be divided into the following groups depending upon their food habits:

Herbivores: Herbivores are animals that depend upon plants and fruits for their nutrition. Cows, goats, sheep, buffaloes, etc. are herbivores.

Carnivores: Carnivores are animals that depend upon other animals for food. Lion, tigers, wolfs are some examples of carnivores.

Omnivores: These include organisms that eat both plants and animals. Humans, bears, dogs, crows are omnivores.

Assimilation

The absorbed food is used for energy, growth and repair of the cells of the body.

The undigested food is removed from the body in the form of faeces. This process is known as egestion.

Amoeba ingests its food with the help of pseudopodia.
The food is engulfed by forming a vacuole and is digested with the help of digestive enzymes.
The digested food is absorbed directly into the cytoplasm by the process of diffusion.
Energy is obtained from the absorbed food that helps in its growth.
The undigested food is egested out of the body of amoeba by rupturing the cell wall.

Frequently Asked Questions

Why is nutrition important for animals.

Nutrition helps in the proper growth and maintenance of the cells. It provides energy to carry out different life processes.

What are the two important modes of nutrition?

The two important modes of nutrition include:

Autotrophic nutrition: In this type of nutrition, the plants and other photosynthetic organisms prepare their own food with the help of sunlight, water and carbon dioxide.
Heterotrophic nutrition: The animals cannot prepare their own food. Therefore, they have to rely on other animals for nutrition. This is known as heterotrophic nutrition.

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Animal nutrition: beyond the boundaries of feed and feeding

By Harinder P.S. Makkar

Food and Agriculture Organization of the United Nations, Animal Production and Health Division, Rome, Italy

Introduction

In a conventional sense Animal Nutrition is the science of feed preparation and feeding i.e. how feeds should be prepared and fed to animals to produce adequate and safe food and non-food materials such as wool or manure. Availability, in a sustained manner, of desired type and quantity of animal feed and its feeding is the foundation of livestock production system. Animal feed availability and animal feeding is a multi-faceted theme. It influences all livestock sub-sectors across production systems. It also has far reaching effects on human nutrition, poverty, food prices and global economy. It impacts almost every sector of the livestock production – from animal reproduction, health and welfare – to farm economic viability, environment, animal product safety and quality .

Over the last 25 years, considerable progress has been made in increasing our understanding of the metabolism in domestic animals, at levels of biological organization, including the whole animal, organ systems, tissues, cells, and molecules. Although the birth of ‘molecular biology’ including ‘omics’ offers exciting opportunities in better understanding the fundamental nutrition, the strategic and applied research in future will focus on better understanding of interactions and dynamics amongst how feed is prepared and fed, animal nutrition and other components such as environment, welfare, biodiversity, product quality and safety

Traditionally, the issues of environment, animal health, animal welfare, product safety and quality have been debated separately for each domain. In this short paper, efforts have been made to weave strands from these domains with animal nutrition and overall sustainability of the livestock operation. This will enable better appreciation of the role of feed and feeding in livestock operation. Also synergies and trade-offs of managing various domains can be established in more integrated and more meaningful ways (Makkar, 2016).

Animal nutrition and productivity

Poor feeding decreases productivity of the animal. A vast array of literature on nutrition-reproduction interactions shows that good feeding increases milk production of lactating animals. It also increases growth rate of meat producing animals, giving more meat. Good nutrition increases reproductive efficiency: higher cyclicity, lower age at first calving, lower inter-calving interval, higher productive life and higher profitability to farmers (FAO/IAEA, 2002). Furthermore, now a good body of evidence exists showing that in utero nutrition has impact on productivity and health of offsprings later in life (Bell and Greenwood, 2013, 2016).

Animal nutrition and farm economics

Feed is financially the single most important element of animal production, irrespective of species and production system. Feed cost can account for up to 70% of the total cost of production of an animal product. High feed costs can wipe out a livestock rearing operation. In 2008, high cost of feeds decreased supply of animal products and increased prices. Optimization of feed use efficiency i.e. producing more with less feed decreases feeding costs and increases economic viability of the livestock operation (Makkar and Beever, 2013).

Animal nutrition and product safety and quality

The safety and quality of the food chain can be affected because of the close link between feed and food-borne pathogens such as Escherichia coli , Salmonella and Campylobacter . These pathogens can get into animal products through animal feed. Mycotoxins, heavy metal, radionuclides, pesticides, dioxin, dibenzofurans, and other toxins present in feed get transferred into animal products affecting animal and human health and product safety. Animal feed safety impacts on animal health, welfare and productivity as well as safety of the human food supply and the livelihood of farmers (FAO 2012b). Microbial species such as Salmonella enterica that are pathogenic for humans are also found in fresh food plants (Franz et al., 2008a). Further, survival of these pathogenic bacteria in soil was also found to be affected by how manure is managed (Franz et al., 2008b) and the composition of the diet fed to cattle that produced the manure (Franz et al., 2005). Safe feed helps to reduce production costs, maintains or increases food quality and reduces feed and food losses and wastes. Contaminated feed has often resulted in food of animal origin being recalled and/or destroyed with significant economic losses for the livestock industries and a negative impact on food security. Feed is an integral part of the food chain, feed production must therefore be subject, in a similar manner as food production, to the quality assurance of integrated food safety systems.

A large body of literature, for example, (Butler, 2014; Vazirigohar et al., 2014) presents opportunities to improve final product quality through manipulation of animal feeding (e.g. increases in: conjugated linoleic acid, 3-omega fatty acids, minerals in animal products, product shelf life). Many of these changes elicit positive effects on human health. Recently, there has been interest in the use of dietary polyunsaturated fatty acids (PUFA), specifically the omega-3 (n-3) fatty acids (FA) α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) to improve sow and piglet performance. Feeding specific n-6 and n-3 FA from either fish (Mateo et al., 2009; Leonard et al., 2010) or flax (Farmer and Petit, 2009) to sows also transfer these fatty acids to their offspring via milk. Feeding cattle with flax-based feeds can increase concentrations of n-3 fatty acids in beef (Drouillard et al., 2004).

Animal nutrition and environment

The livestock production is resource demanding: it occupies 30% of the world’s ice-free surface and consumes 8% of global human water use, mainly for the irrigation of feed crops (FAO, 2009a). The area dedicated to feed-crop production represents 33% of total arable land. In addition, animal products generally have a much higher water and carbon footprints than plant-based foods (Mekonnen and Hoekstra, 2012; Ripple et al., 2014) and livestock sector contributes approximately 14.5% of all anthropogenic greenhouse gas (GHG) emissions (7.1 Gigatonnes of CO 2 -equivalent per year). Globally, the production, processing and transport of feed account for about 45% of the GHG emission from livestock sector. At a species level, feed production constitutes 47% and 57% of emissions from pork and chicken supply chains, respectively. For cattle, small ruminants and buffalo, feed production contributes 36%, 36% and 28% of the total emissions respectively (Gerber et al., 2013). Feed nutrients (70 to 90% of nitrogen and phosphorus) are lost into the environment through manure, which if not managed properly can lead to environmental pollution. Livestock contribute 37% of anthropogenic CH 4 , mostly from enteric CH 4 (FAO, 2009a), which is largely feed dependent. Feed production and use also impact land use and land use change (Gerber et al., 2013), which also leads to loss of sequestered carbon and biodiversity. Both environment and biodiversity degradation have linkage with ecosystem and human health. Smart feeding practices, especially the balanced ration approach i.e. feeding a diet containing nutrients such as protein, carbohydrates and minerals in the right proportion and in an amount that meets the nutrient requirements of animals for achieving the targeted production would decrease nitrogen, phosphorus and methane release in the environment and the biodiversity loss (FAO, 2012a; Garg et al., 2013). Use of locally adapted feed resources is also expected to conserve biodiversity.

Animal nutrition and food-feed competition

In 2012–2013, 795 million tonnes of cereals (one-third of total cereal production) were used in animal feed and by 2050 an additional 520 million tonnes would be required for feeding livestock. In 2000, 78% of feed grains were fed to pigs and poultry in regions where industrial intensive system dominate (FAO, 2013a). In the last 20 years, there has been an increased interest in forage-fed beef for multiple reasons (health related, environmental concerns, and welfare issues) (Scaglia et al., 2014). Use of smart feeding options such as decrease in the level of grains in the concentrate by using agro-industrial by-products, increase in green fodder use, feeding of total mixed ration instead of feeding individual ingredients, use of chopped forages, increase in digestibility of crop residues could contribute to decrease in grain in diet.

Animal nutrition and feed-fuel competition

About 10% ( ca 120 million ones) of global production of course grains are used for bioethanol production (FAO, 2013a). A continued rapid expansion of biofuel production up to 2050 would lead to the number of undernourished pre-school children in Africa and South Asia being 3 and 1.7 million higher than would have been otherwise the case (FAO, 2009b). Efficient use of alternate novel feed resources such as biofuel coproducts e.g. glycerol, dried distillers grains, gluten meal, cassava residue, Camelina s ativa meal, sweet sorghum residue, kernel meal from the non-toxic Jatropha, pongamia meal, castor meal, palm kernel meal, and algae residue (Makkar, 2013) would contribute to decreasing feed-fuel competition.

Animal nutrition and animal health

Improper nutrition (unbalanced diet, under or over feeding) impacts health adversely directly, and also makes animals more prone to diseases. Furthermore, in case of disease, corrective measures in the form of medicines are less or not effective. Vaccination done during the period of improper nutrition might also properly protect the animals. Correct nutrition can reduce infectious afflictions by enhancing cell-tissue integrity and optimizing defence mechanisms of the immune system (FAO, 2012b). Feeding of balanced ration has been shown to increase immuno-globulin levels in blood, suggesting higher immunity (FAO, 2012a). Supplements such as minerals, antioxidants and amino acids such as methionine also play a role in immune stimulation (Jankowski et al., 2014; Celi et al., 2014). Good nutrition is also a biosecurity measure to control zoonotic and infectious diseases.

Animal nutrition and animal welfare

Feeding to sustain high production levels, nutrient deficiency or excess can lead to metabolic disorders in ruminants such as acidosis and lameness causing welfare issues; whilst breeding animals of monogastric species which are restrict-fed to optimise health and production may suffer from chronic hunger. A number of welfare problems in ruminants are elicited by the feeding of poor quality or unsafe feeds. A properly balanced diet free of undesirable substances and water supplied in adequate amounts avoid physical and psychological suffering from hunger and thirst; furthermore correct nutrition is crucial for optimal performance and to sustain optimal fitness. Further information on adverse effects of improper animal nutrition on animal welfare and the corrective measures is available in FAO (2012b).

Animal nutrition and global security

Increased food-feed-fuel competition can lead to food shortages, high food price and high volatility in prices. This could adversely impact global food security and could possibly trigger civil unrest and conflict among masses and between people and government. Government stability and governance could be affected, resulting on global insecurity. This has happened in the recent past in some developing counties. Animal nutritionists have a role as a peacemaker also by playing with the feeds and feeding in a manner that there is least food-feed-fuel competition and the feed efficiency is optimized to achieve more animal products from less feed.

The choice of feed constituents (diet) and their consumption affect animal productivity (including reproductive efficiency), greenhouse gas emissions (GHG), animal health, animal-sourced food safety and quality and animal welfare. The production of those dietary constituents has an impact on water quality, GHG and land use. The animal well-being and possibly human well-being may be influenced by animal diets.

The aforesaid challenges and issues are being addressed through the FAO’s initiative: Towards Sustainable Animal Diet. A Sustainable Animal Diet may be defined as the diet that has the core traits, i.e. balanced in all nutrients, free from deleterious components, meet production objective, generate animal products that are safe for human consumption and integrates the Three-P dimensions of sustainability ( Planet, People and Profit ; inter alia, have been used to describe the term, implying ecological soundness, social equity and economic growth) and also the ethical dimension (Makkar and Ankers, 2014). Translating the Sustainable Animal Diet Framework into action would be beneficial for the animal, the environment and the society, and is likely to generate socio-economic benefits (FAO, 2014); and animal nutritionists have a vital role in achieving this. Animal nutritionists put in place strategies that increase nutrient use efficiency in animal food chain i.e. enhance transfer of nutrients from feed to animal products. These strategies simultaneously decrease nutrient excretion into the environment, which assist in controlling pollution. Furthermore the strategies also enhance animal health, welfare and production. Examination of undesirable constituents in feed, integrated with sound quality control systems (FAO, 2013b), also contribute in enhancing animal product safety and preventing feed wastage. All these efforts fall in the domain of animal nutritionists.

In the changing scenarios – achieving high production is not only sufficient – high animal productivity, animal product safety and quality, animal welfare and health and protection of environment and biodiversity are also being increasingly demanded. Increasing awareness and emphasis on animal welfare, environment, product safety and quality have become a priority in food production systems involving animals. In this changing landscape animal nutritionists should consider themselves fortunate because they could influence most of the activities of the livestock Sector. Animal nutritionists are at the cross-roads where almost all sectors and services of the livestock industry meet. They are in the driver’s seat for taking the livestock sector towards sustained development following the principles of the Sustainable Animal Diet. Substantial contribution can be made by animal nutritionists in: producing adequate, safe and nutritious food in a humane way in the face of rapid population growth; saving the environment, biodiversity and the way of life of pastoralists and ranchers; bringing smallholder livestock farmers out of poverty; promoting industrial growth, alleviating malnutrition especially in pregnant ladies and growing children that is related to inadequate vitamins, minerals and amino acids consumption; safeguarding public goods including human health; and promoting global security.

Bell, A.W. and Paul L. 2013. Greenwood Optimizing maternal cow, grower and finisher performance in beef production systems. In: Optimization of feed use efficiency in ruminant production systems. Proceedings of the FAO Symposium, 27 November 2012, Bangkok, Thailand. FAO Animal Production and Health Proceedings, No. 16. Rome, FAO and Asian-Australasian Association of Animal Production Societies (available at: http://www.fao.org/docrep/018/i3331e/i3331e.pdf ).

Bell, A.W. and Paul L. 2016. Nutrition during gestation influences postnatal productivity of ruminant livestock. Broadening Horizons 30, Feedipedia (available at: http://www.feedipedia.org/content/nutrition-during-gestation-influences-postnatal-productivity-ruminant-livestock ).

Butler, G. 2014. Manipulating dietary PUFA in animal feed: implications for human health, Proc. Nutr. Soc. 73: 87–95.

Celi, P., Chauhan, S.S., Cottrell, J.J, Dunshea, F.R., Lean, I.J., Leury, B.J. and Liu, F. Oxidative stress in ruminants: enhancing productivity through antioxidant supplementation (available at: http://www.feedipedia.org/content/oxidative-stress-ruminants-enhancing-productivity-through-antioxidant-supplementation ).

Drouillard, J. S., M. A. Seyfert, E. J. Good, E. R. Loe, B. Depenbusch, and R. Daubert. 2004. Flaxseed for finishing beef cattle: Effects on animal performance, carcass quality, and meat composition. In: Proc. 60th Flax Institute, March 17-19, Fargo, ND. p. 108–117.

FAO. 2009a. The State of Food and Agriculture: Livestock in the Balance, FAO Rome (available at: http://www.fao.org/docrep/012/i0680e/i0680e.pdf ).

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FAO. 2012b. Impact of animal nutrition on animal welfare – Expert Consultation 26−30 September 2011 – FAO Headquarters, Rome, Italy. Animal Production and Health Report. No. 1. Rome (available at: http://www.fao.org/docrep/017/i3148e/i3148e00.pdf ).

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Franz E, van Diepeningen AD, de Vos OJ and van Bruggen AHC. 2005. Effects of cattle feeding regimen and soil management type on the fate of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in manure, manure-amended soil, and lettuce. Appl EnvironMicrobiol 71:6165–6174.

Garg, M.R., Sherasia, P.L., Bhanderi, B.M., Phondba, B.T., Shelke, S.K. and Makkar, H.P.S. 2013. Effects of feeding nutritionally balanced rations on animal productivity, feed conversion efficiency, feed nitrogen use efficiency, rumen microbial protein supply, parasitic load, immunity and enteric methane emissions of milking animals under field conditions. Animal Feed Science and Technology 179: 24–35.

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Makkar, H.P.S. 2016. Animal nutrition in a 360-degree view and a framework for future R&D work: towards sustainable livestock production. Anim. Prod. Sci. – Perspectives on Animal Biosciences http://dx.doi.org/10.1071/AN15265

Makkar, H.P.S. and Beever, D. 2013. Optimization of feed use efficiency in ruminant production systems. Proceedings of the FAO Symposium, 27 November 2012, Bangkok, Thailand. FAO Animal Production and Health Proceedings, No. 16. Rome, FAO and Asian-Australasian Association of Animal Production Societies (available at: http://www.fao.org/docrep/018/i3331e/i3331e.pdf ).

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Scaglia, G., J. Rodriguez, J. Gillespie, B. Bhandari, J. J. Wang and K. W. McMillin. 2014. Performance and economic analyses of year-round forage systems for forage-fed beef production in the Gulf Coast. doi:10.2527/jas.2014-7838 Journal of Animal Science 2014 92:5704-5715.

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Photo credits

Stéphanie Maylon, CIAT, CC-BY-SA-2.0; Henning, R. K., Wikimedia Commons, CC-BY-SA- 2.5

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The nutritional requirements of most animals are relatively extensive and complex compared with the simple requirements of plants. The nutrients used by animals include carbohydrates, lipids, nucleic acids, proteins, minerals, and vitamins.

■ Carbohydrates are the basic source of energy for all animals. Animals obtain their carbohydrates from the external environment (compared with plants, which synthesize carbohydrates by photosynthesis). About one-half to two-thirds of the total calories every animal consumes daily are from carbohydrates. Glucose is the carbohydrate most often used as an energy source. This monosaccharide is metabolized during cellular respiration (see Chapter 6), and part of the energy is used to synthesize adenosine triphosphate (ATP). Other useful carbohydrates are maltose, lactose, sucrose, and starch.

■ Lipids are used to form cellular and organelle membranes, the sheaths surrounding nerve fibers, and certain hormones. One type of lipid, fats, are extremely useful energy sources.

■ Nucleic acids are used for the construction of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and ATP. Animals obtain their nucleic acids from plant and animal tissues, especially from cells that contain nuclei. During digestion, the nucleic acids are broken down into nucleotides, which are absorbed into the cells.

■ Proteins form the framework of the animal body. Proteins are essential components of the cytoplasm, membranes, and organelles. They are also the major components of muscles, ligaments, and tendons, and they are the essential substances of enzymes. Proteins are composed of 20 kinds of amino acids. Although many amino acids can be synthesized, many others must be supplied in the diet. During digestion, proteins are broken down into their constituent amino acids, which are absorbed into the body.

■ Among the minerals required by animals are phosphorus, sulfur, potassium, magnesium, and zinc. Animals usually obtain these minerals when they consume plants. Vitamins are organic compounds essential in trace amounts to the health of animals. Vitamins can be water soluble or fat soluble. Water-soluble vitamins must be consumed frequently, while fat-soluble vitamins are stored in the liver in fat droplets. Among the many essential vitamins are vitamin A for good vision, vitamin B for substances used in cellular respiration (FAD, NAD, and coenzyme A), and vitamin D to assist calcium absorption in the body.

Animals obtain their nutrients through a broad variety of feeding patterns. Sponges, for example, feed on small particles of food that enter their pores. Other aquatic organisms, such as sea cucumbers, wave their tentacles about and trap food on their sticky surfaces. Mollusks, such as clams and oysters, feed by filtering materials through a layer of mucus in their gills. Certain arthropods feed exclusively on fluids.

Some animals feed on food masses, and they usually have organs for seizing, chewing, and consuming food. Herbivores are animals that eat only plants, while carnivores are animals that eat only other animals. Omnivores, which consume both plants and animals, are typified by humans.

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Nutrition Essay | Essay on Nutrition for Students and Children in English

February 12, 2024 by Prasanna

Nutrition Essay: The section of science that deals with the interpretation of nutrients and food in the animal system to sustain a healthy life and to keep health issues at check is known as ‘nutrition.’ The topic of nutrition is vulnerably proportional to the economic stability of a society or a country at a broader aspect.

A necessity that keeps life running at the cost of money, to which a noticeable chunk of the society is deprived but remains unattended to, is also ‘nutrition.’

You can also find more Essay Writing articles on events, persons, sports, technology and many more.

Long and Short Essays on Nutrition for Students and Kids in English

We are providing students with essay samples on a long essay of 500 words and a short essay of 150 words on the topic nutrition for reference.

Long Essay on Nutrition 500 Words in English

Long Essay on Nutrition is usually given to classes 7, 8, 9, and 10.

As the name suggests, ‘nutrition’ includes in itself’ nutrients’ which can be broadly classified as carbohydrates, proteins, fats, vitamins, minerals, roughage, and water. A balanced amount of these nutrients in the right proportions constitute a healthy diet.

The words’ balanced’ and ‘right proportions’ mentioned previously are key to life when it comes to consuming nutrients. ‘Optimum Nutrition’ is defined as eating the right amount of nutrients in a proper schedule to achieve the best performance and longest possible lifetime in good health. The importance of nutrition can be visibly highlighted by the increasing number of nutrient deficiency diseases such as night blindness, scurvy, cretinism, anemia, and nutrient excess health-threatening conditions like obesity, metabolic syndrome, and other cardiovascular anomalies.

Undernutrition in underdeveloped and developing countries has been marked by malnutrition due to lack of even the basic staple nutrients causing diseases like marasmus and kwashiorkor. Animal nutrition on the molecular level comes from nitrogen, carbon, and hydrogen compounds. Nutrients are the building blocks of the food chain, which interlink to form food webs and influence world food production via biodiversity.

Similarly, plant nutrition is referred to as the chemicals that are necessary for plant growth and other physiological processes in plants like metabolism, transport, photosynthesis, etc. Nutrients essential for plants are obtained from the soil, air, sunlight, and as a whole from the earth; thus, the nutrients can be recycled and renewed, making it easily available for sustenance of life.

Fatigue, tiredness, and apathy are common among the working class as well as students. To feel refreshed, motivated as well as reenergized, all we require is the proper nutrition for our systems. Nutrition helps an individual attain optimal health throughout life as well as boost self-esteem.

Eating a balanced diet improves a person’s health and well-being and reduces risks of major causes of death. The other benefits of nutrition include a healthy heart, strength in teeth and bones, maintains good brain health, boosts immunity, bolsters the body to fight against diseases, keeps higher energy levels, and keeps the bodyweight at check. With such a minimum as maintaining our diet comes the strength of independence or self-dependence. The topic of nutrition has gained its importance by being studied and researched over for years. Nutrition is taught as a subject in various levels of education, and professions such as farmers, scientists, nutritionists, dietitians, health counselors, and doctors who form the pillar of our society are all based on nutrition fundamentals.

Progressive research works from various parts of the world on ‘nutrition’ has helped in aiding health conditions for the living, yet a big section of society is not reached out for proper food supplies. With the current progressive rate of scientific enhancement in the field of nutrition, resulting in increasing food production, we should be able to reach out to those who are dying due to the lack of something as basic as food, which should be available to everyone equally.

Short Essay on Nutrition 150 Words in English

Short Essay on Nutrition is usually given to classes 1, 2, 3, 4, 5, and 6.

‘Nutrition’ is one of the fundamentals of living that can be defined as the assimilation of food into living systems that help life function daily.

The classification of nutrition can vary from plants to animals, but they are interlinked by the food chains that form the ecosystem’s structural framework.

The components of nutrition include carbohydrates, proteins, fats, fibers, vitamins, minerals, water, and roughage when consumed in the right proportions, gives it the name of ‘balanced diet.’ Likewise, in plants, chemicals being obtained through absorption, transpiration, and photosynthesis are the nutrients that help in their internal processes.

The benefits of following a good nutritional diet plan ranges from good physical health to proper well-being and ensure a good immune system. Good nutrition with proper and regular exercise can assure a person a disease-free future. Even during ailment, proper nutrition can help cure a patient faster and safer. Hence adequate nutrition is a key to a healthy life and a necessity that should be looked after at any cost.

10 Lines on Nutrition in English

Nutrition is a natural demand for every source of life on earth.
Being deprived of nutrition is as severe as being deprived of any other fundamental rights.
Lack of nutrition can give rise to lethal diseases.
The knowledge of the classification of nutrients and their biological systems’ roles should be known to all.
The benefits of proper nutrition ensure physical and mental well-being.
Malnutrition has always been an issue adding to the rise in global hunger for years, as reported by the United Nations.
As reported, 1.5 million children die annually due to the lack of proper nutrition.
The Human Body’s primary requirement is nutrition. It would be impossible to sustain life without it.
Studies on nutrition should be encouraged.
Lack of nutrition gives rise to social disparity and discrimination.

FAQ’s on Nutrition Essay

Question 1. What are the benefits of proper nutrition?

Answer: Proper nutrition helps build the immune system of the body and maintain good physical and mental health.

Question 2. What is a balanced diet?

Answer: A balanced diet includes all types of the necessary nutrients in the right amount at proper intervals, helping maintain the various human and plant organ systems.

Question 3. What are the results due to a lack of nutrition?

Answer: The lack of proper nutrition can severely result in malnutrition, which is currently a cause of global hunger.

Question 4. What food should be consumed daily?

Answer: A diet that includes all of the fundamental nutrients and water in the right amount should be consumed daily with regular exercise.

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About Organismal Biology
Phylogenetic Trees and Geologic Time
Prokaryotes: Bacteria & Archaea
Eukaryotes and their Origins
Land Plants
Animals: Invertebrates
Animals: Vertebrates
The Tree of Life over Geologic Time
Mass Extinctions and Climate Variability
Multicellularity, Development, and Reproduction
Animal Reproductive Strategies
Animal Reproductive Structures and Functions
Animal Development I: Fertilization & Cleavage
Animal Development II: Gastrulation & Organogenesis
Plant Reproduction
Plant Development I: Tissue differentiation and function
Plant Development II: Primary and Secondary Growth
Principles of Chemical Signaling and Communication by Microbes
Animal Hormones
Plant Hormones and Sensory Systems
Nervous Systems
Animal Sensory Systems
Motor proteins and muscles
Motor units and skeletal systems

Nutrient Needs and Adaptations

Nutrient Acquisition by Plants
Water Transport in Plants: Xylem
Sugar Transport in Plants: Phloem
Nutrient Acquisition by Animals
Animal Gas Exchange and Transport
Animal Circulatory Systems
The Mammalian Cardiac Cycle
Ion and Water Regulation and Nitrogenous Wastes in Animals
The Mammalian Kidney: How Nephrons Perform Osmoregulation
Plant and Animal Responses to the Environment

Learning Objectives

Differentiate between photo-, chemo-, auto-, and hetero-trophies
Distinguish between essential, beneficial, macro- and micro-nutrient requirements for plants and animals
Recognize that both insufficient and excessive amounts of nutrients can have detrimental effects on organism’s growth and health
Predict the symptoms of nutrient deficiencies in plants based on whether the nutrient is mobile or immobile in plant tissues
Describe the diversity of adaptations for acquisition of nutrients in plants, especially nitrogen acquisition
Describe the diversity of adaptations for acquisition of nutrients in animals, especially mouth structures, presence of specific digestive system structures, and the role of the gut microbiome in digestion

Living Cells Need Materials to Grow: Nutrients

The information below was adapted from OpenStax Biology 22.3

Recall from our discussion of prokaryotes metabolic diversity that all living things require a source of energy and a source of carbon , and we can classify organisms according to how they meet those requirements:

Phototrophs (phototrophic organisms) obtain their energy from sunlight.
Chemotrophs (chemosynthetic organisms) obtain their energy from chemical compounds.
Autotrophs (autotrophic organisms) are able to fix (reduce) inorganic carbon such as carbon dioxide
Heterotrophs (heterotrophic organisms) must obtain carbon from an organic compound

These terms can be combined to classify organisms by both energy and carbon source:

Photo auto trophs obtain energy from sunlight and carbon from carbon dioxide
Chemo hetero trophs obtain energy and carbon from an organic chemical source
Chemo auto trophs obtain energy from inorganic compounds, and they build their complex molecules from carbon dioxide.
Photo hetero trophs use light as an energy source, but require an organic carbon source (they cannot fix carbon dioxide into organic carbon).

Essential Macronutrients and Micronutrients

The information below was adapted from OpenStax Biology 22.3, OpenStax Biology 23.2 , and OpenStax Biology 24.1

Cells are made of more than just carbon; for cells to build all of the molecules required to sustain life, they need certain substances collectively called nutrients . A nutrient is essential if an organism cannot synthesize it and must acquire it from another source. In contrast, a beneficial nutrient can stimulate growth and development but is not required and/or could be substituted by another nutrient.

Essential nutrients that are required in large amounts are called macronutrients , and those required in smaller or trace amounts are called micronutrients . Just a handful of elements are considered macronutrients across all domains of life: carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. (A mnemonic for remembering these elements is the acronym CHONPS .)

Carbon is the major element in all biological macromolecules: carbohydrates, proteins, nucleic acids, lipids, and many other compounds. Carbon accounts for about 50 percent of the composition of the cell.
Nitrogen represents 12 percent of the total dry weight of a typical cell and is a component of proteins, nucleic acids, and other cell constituents. Most of the nitrogen available in nature is either atmospheric nitrogen (N 2 ) or another inorganic form. Diatomic (N 2 ) nitrogen, however, can be converted into an organic form only by certain organisms, called nitrogen-fixing organisms.
Both hydrogen and oxygen are part of many organic compounds and of water.
Phosphorus is required by all organisms for the synthesis of nucleotides and phospholipids.
Sulfur is part of the structure of some amino acids such as cysteine and methionine, and is also present in several vitamins and coenzymes.
Depending on the organism, other important macronutrients include potassium (K), magnesium (Mg), calcium (Ca), and sodium (Na).

In addition to these macronutrients, cells require micronutrients or trace elements, which are elements needed in small amounts. For example, iron (Fe) is necessary for the function of the cytochromes involved in electron-transport reactions.

Nutritional Needs in Plants

The information below was adapted from OpenStax Biology 31.1 , OpenStax Biology 31.3 , OpenStax Biology 24.3

Plants require light , water and about 20 essential nutrients (including both macro- and micronutrients) to support all their biochemical needs. Depending on the species, some plants have additional essential nutrients. Here we will describe only a handful of essential macronutrients that are common to all plants:

Carbon (C) from the air is used by plants to make glucose (sugar) which can be ultimately used to construct cellulose. Cellulose is the main structural component of the plant cell wall, and it is the most abundant organic compound on earth.
Nitrogen (N) is part of proteins and nucleic acids, and is also used in the synthesis of some vitamins. While there is an overwhelming amount of nitrogen in the air (79% of the atmosphere is nitrogen gas), the nitrogen in the air is not biologically available due to the triple bond between the nitrogen atoms. Only a few species of bacteria are capable of “fixing” nitrogen to make it bioavailable; thus nitrogen is often a limiting factor for plant growth.
Phosphorus (P) is necessary to synthesize nucleic acids and phospholipids. As part of ATP, phosphorus enables food energy to be converted into chemical energy through oxidative phosphorylation. Likewise, light energy is converted into chemical energy during photophosphorylation in photosynthesis, and into chemical energy to be extracted during respiration. Phosphorous is typically available in a form that is not readily taken up by plant roots; the form that is bioavailable is present in small quantities and rapidly “fixed” into the bioavailable form once again. Phosphorus is therefore often a limiting factor for plant growth .
Potassium (K) is important because of its role in regulating stomatal opening and closing. As the openings for gas exchange, stomata help maintain a healthy water balance; a potassium ion pump supports this process. Potassium may be present at low concentrations in some types of soil, and potassium is the third most common limiting factor for plant growth .

Based on the information above, you might not be surprised to learn that nitrogen, phosphorus, and potassium are the three most common components in commercial fertilizers.

Plants are able to continuously acquire carbon from the air (in the form of carbon dioxide); however, as stationary organisms nutrient acquisition can become a challenge if the soil becomes depleted of a particular nutrient. Most land plants address this challenge by continually growing roots throughout the soil as they mine for minerals and water.

Both deficiencies and excessive amounts of nutrients, whether macronutrients or micronutrients, can adversely affect plant growth. Deficiencies occur when a plant does not have enough of a particular nutrient to support biological functions performed by that nutrient. Conversely, excessive amounts of some nutrients can be toxic to certain tissues or cell types.

Depending on the specific nutrient, a deficiency can cause stunted growth, slow growth, or chlorosis (yellowing of the leaves). Extreme deficiencies may result in leaves showing signs of cell death. The symptoms of a given nutrient deficiency depends partly on the nutrient’s function, and partly on whether the nutrient is mobile within the plant tissue:

if a plant depletes the soil of a nutrient that fixed into existing tissue and cannot be moved to a different tissue, then new growth will show signs of the deficiency
if a plant depletes the soil of a nutrient that is mobile within the plant tissue, then old growth is likely to show signs of the deficiency rather than new growth, because plant is likely to move the nutrient from older to newer tissues

Adaptations for Nutrient Acquisition in Plants

Plants generally obtain carbon in two different ways:

Autotrophic plants can make their own food from inorganic raw materials, such as carbon dioxide and water, through photosynthesis in the presence of sunlight. Green plants are included in this group.
Heterotrophic plants lack chlorophyll and thus are unable to synthesize their own organic carbon; instead, they are parasitic and draw all of their nutrients from a host plant:

Acquisition of other nutrients (for example, nitrogen, phosphorous, and potassium) generally occurs via the roots which are embedded in soil for most plants; however, there are many variations and adaptations across plant groups to support this process (especially for nitrogen acquisition):

Mycorrhizal fungi: most plants (~80-90%) rely on mycorrhizal fungi to facilitate the uptake of mineral nutrients from the soil. Fungi form symbiotic associations called mycorrhizae with plant roots, in which the fungi actually are integrated into the physical structure of the root. Mycorrhizae help increase the surface area of the plant root system because the fungal hyphae can spread far beyond the plant root system; as a result, the plant obtains nutrients such as nitrogen and phosphorus from the soil or organic matter decomposed by the fungi, and the fungus obtains sugars and other nutrients from the plant root. Mycorrhizae also function as a physical barrier to plant pathogens.

Legumes and nitrogen-fixing bacteria: nitrogen is the most abundant element in Earth’s atmosphere; however, atmospheric nitrogen is not biologically available to plants. The process of biological nitrogen fixation (BNF) coverts atmospheric nitrogen (N2) to ammonia (NH3); this process is carried out exclusively by a few species of nitrogen-fixing bacteria. The most important source of BNF is the symbiotic interaction between soil bacteria and legume plants, including many agricultural crops important to humans such as peanuts, beans, chickpeas, soybeans, and lentils (among many others).

Carnivorous plants: Carnivorous plants have specialized leaves that and digest insects or small vertebrates, typically as an adaptation to supplement nutrient access in extremely nutrient-poor soils. Examples include Venus flytrap, pitcher plants, and sundews. Once trapped, fluids and enzymes break down the prey and nutrients are absorbed by the leaf. It is important to note that carnivorous plants are autotrophic rather that heterotrophic (they synthesize their own carbon via photosynthesis); they are carnivorous not to acquire carbon, but to acquire other nutrients that are unavailable in their nutrient-poor soils.

Nutritional Needs in Animals

The information below was adapted from OpenStax Biology 34.0 , OpenStax Biology 34.1 , and OpenStax Biology 34.2

Like all forms life, animals require (at minimum) carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur as building blocks for biological molecules. Unlike photoautotrophic plants we have just described, which obtain their required energy from the sun and their required nutrients from carbon dioxide in the air and nutrients from the soil, animals are chemoheterotrophs and must obtain both their energy and their nutrients by eating other organisms. Animals can be classified based on the type(s) of organisms they eat (more on this concept later on in this reading):

Herbivores are animals that primarily eat plants
Carnivores are animals that primarily eat other animals
Omnivores are animals that eat both plants and animals

Animals obtain their energy and nutrients from three primary organic precursors:

Carbohydrates (including both simple and complex sugars) are the primary source of organic carbon for herbivores and omnivores; carnivores must rely on protein and lipids as sources of carbon.
Proteins are dietary sources of nitrogen and sulfur (and carbon for carnivores).
Fats are also significant sources of chemical energy, producing more energy per gram than carbohydrates. Dietary fats are also necessary to aid the absorption of fat-soluble vitamins and the production of fat-soluble hormones.

While the animal body can synthesize many of the molecules required for function from the organic precursors, there are some nutrients that need to be consumed from food. These nutrients are termed essential nutrients , meaning they must be eaten because the animal cannot synthesize them. Essential nutrients vary among animal species (for example, almost all mammals can synthesize vitamin C; exceptions include humans, non-human primates, guinea pigs, and bats which must have a dietary source of vitamin C). The four classes of essential nutrients are:

Essential amino acids are necessary as protein building blocks. For humans, all essential amino acids are available from meat sources; because there are no plants that contain all essential amino acids, vegetarians and vegans must eat sufficient quantities of both grain and legume protein sources
Essential fatty acids are necessary as fat building blocks (also used as signaling molecules and many other functions). For humans, there are only two essential fatty acids, as we are able to synthesize nearly all of the fatty acids needed.
Vitamins are organic compounds needed in small amounts. Vitamins may be water-soluble (such as vitamin C), meaning they are easily excreted in urine, or fat-soluble (such as vitamin D), meaning that the can accumulate in adipose (fat) tissue.
Minerals are inorganic compounds needed in small amounts. Minerals include a variety of elements such as calcium, phosphorus, sulfur, potassium, sodium, iron, and many others.

As with plants, both deficiencies and excessive amounts of nutrients can adversely affect animal growth and health. Deficiencies occur when an animal does not have enough of a particular nutrient to support biological functions performed by that nutrient. Conversely, excessive amounts of some nutrients can be toxic to certain tissues or cell types.

The video below provides an overview of the nutritional needs of humans:

Adaptations for Nutrient Acquisition in Animals

The information below was adapted from OpenStax Biology 34.0 , OpenStax Biology 34.1 OpenStax Biology 34.2

As noted above, animals obtain both nutrients and energy by eating other organisms. At the cellular level, the biological molecules necessary for animal function are amino acids, lipid molecules, nucleotides, and simple sugars. However, the food consumed consists of proteins, fats, and complex carbohydrates. Animals must convert these macromolecules into the simple molecules required for maintaining cellular functions like assembling new biological molecules. The conversion of the food into nutrients is a multi-step process involving digestion and absorption. During digestion, food particles are broken down to smaller components, and later, they are absorbed by the body (more on digestion and absorption later in a future reading).

As noted above, animals can be classified into the following categories based on their diet:

Herbivores are animals whose primary food source is plant-based. Examples of herbivores include vertebrates like deer, koalas, and some bird species, as well as invertebrates such as crickets and caterpillars. These animals have evolved digestive systems capable of handling large amounts of plant material, which require additional digestive processing steps compared to animal material. Herbivores can be further classified into frugivores (fruit-eaters), granivores (seed eaters), nectivores (nectar feeders), and folivores (leaf eaters).

Carnivores are animals that eat other animals. Lions, tigers, snakes, sharks, and orcas (killer whales) are examples of vertebrate carnivores; invertebrate carnivores include sea stars, spiders, and ladybugs.

Omnivores are animals that eat both plants and animals. Humans, bears and chickens are example of vertebrate omnivores; invertebrate omnivores include cockroaches and crayfish.

Regardless of what an animal eats, it must ingest (swallow) its food in order to digest it (contrast this process with that of fungi, which are chemoautotrophs chemoheterotrophs like animals, but which secrete digestive enzymes outside of their body to break down food before absorbing the nutrients through their hyphae). There are many adaptations across animal species to facilitate ingestion and digestion of different food sources:

Example adaptations for ingestion of different foods:

bees have structures that facilitate lapping up of nectar
grasshoppers have structures to support chewing of vegetation
butterflies have straw-like structures that allow for siphoning of nectar
Jaw structure : Vertebrate jaw structure varies widely across species; for example, snakes have an extra bone on either side of the jaw, as well as flexible tendons joining the center of the lower jaw, which allow snakes to open their jaws wide enough to swallow prey that appears to be larger than their heads
Incisors work well for biting
Canines work well for tearing chunks of food from a larger mass; canines tend to be larger in carnivores
Molars work well for chewing; molars tend to be flatter and more numerous in herbivores and omnivores

Example adaptations for digestion of different foods:

Symbiotic microorganisms: the digestive tract of all animals contain symbiotic microorganisms which perform their own digestion of food within the animal. In most cases, the relationship is mutually beneficial: the microorganisms have a steady supply of nutrition and live within a controlled environment protected from predators, and the animal has access to the nutrient byproducts produced by the microorganisms as a result of their digestive activities. In fact, many vitamins and other nutrients, such as vitamin K, are inaccessible in food materials until released by the digestive activity of symbiotic bacteria in an animal’s gut
a large cecum (present in non-ruminant herbivores, such as rabbits and other herbivorous rodents), which is a side pouch of the large intestine that houses symbiotic bacteria (the appendix is the vestigial cecum in humans)
a rumen and associated organs (present in ruminant herbivores, such as cows), which is essentially a fermentation vat within the digestive tract to house symbiotic bacteria and protists capable of digesting cellulose
Gizzard: in both invertebrates and vertebrates that lack teeth entirely (such as birds) or teeth/jaw structure to support chewing (such as many reptiles), the gizzard is often the side of mechanical breakdown of food. The gizzard is a stomach-like chamber that combines powerful muscle contractions as well as small pebbles, sand, or grit eaten by the animal to mechanically break down food items to facilitate their digestion.
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“Science has a simple faith, which transcends utility. It is the faith that it is the privilege of man to learn to understand, and that this is his mission.”

I. Introduction to Nutrition

New Terms Acid Detergent Fiber Ash Crude Fiber Crude Protein Detergent Fiber System Dry Matter Ether Extract Feed Fundamental Nutrients Neutral Detergent Fiber Nitrogen Free Extract Nutrient Proximate Analysis

Chapter Objectives

To introduce and discuss the basic concepts of nutrition and some basic nutritional terminology
To introduce and discuss fundamental nutrients in animal diets

Concepts of Nutrition

Nutrition is a relatively new science. It is an applied science that encompasses the principles of other sciences, such as chemistry, biochemistry, and physiology.

Animal nutrition deals with the nutritional needs of food-producing, companion, or service animals. It is the science of preparation or formulation of feed for animals that produce food (e.g., meat, milk) or nonfood materials (e.g., wool). Animal nutrition also is an integrative science, as it deals with the different steps by which the animal assimilates feed, or food, and uses it for its growth, health, and performance (e.g., meat, milk, and egg production and service).

In addition to the health, welfare, or productivity of the animal, food animal nutrition is also very important due to economic (e.g., feed cost) and environmental aspects (manure and undigested, wasted nutrients, such as phosphorus and nitrogen, contaminating air, soil, and water), as well as nutritional quality (eggs, meat, milk).

Nutrients are chemical elements or compounds present in feed that support health, basic body maintenance, or productivity. Fundamental nutrients include water, carbohydrates, protein, fat, vitamins, and minerals.

Why Is Nutrition Important in Livestock?

Nutrition is important for all organisms. However, in food-producing animals, it is especially important due to the nature of the production systems (e.g., confinement), the economics of production, or the products (e.g., meat, eggs, milk) generated.

Feed nutrients, such as nitrogen and phosphorus, are lost into the environment through manure, which if not managed properly, can lead to environmental pollution. The emission of methane and nitrous oxide from manure is also to some extent dependent on the nature of feed being fed to livestock. Use of good-quality feeds with high digestibility will minimize or reduce environmental pollution.

Feed represents the major expense for raising food animals. For example, feed amounts to more than 65% of the expense in swine or poultry production systems. As world population increases, there is an additional demand for food, land, and energy. As a result, feed production with limited resources will be a challenge in the context of sustainability.

Consumers’ perception of the effect of diet on health has increased markedly over the past two decades. This perception has an impact on consumer food choices, especially with regards to certain nutrients in animal products (e.g., saturated fats, cholesterol). Therefore, nutrition is important for producing health-promoting foods for human consumption.

Improper nutrition (under- or overfeeding) can affect animal health. Balanced nutrition can enhance immune health, welfare, productivity, and longevity. Overall, the nutrition of livestock is very important due to their dependence on humans, especially when food animals are raised in confinement. It is also important for economic reasons, to produce human food with limited resources, and to enhance animal productivity, health, and welfare.

Why Nutrition is Important

Dependence on humans (e.g., confinement)
Environmental protection
Enhancement of food production with limited resources
Human health-promotion and food quality enhancements
Animal health and welfare

Nutrient Analysis of Feedstuffs

The 19th century had a significant impact on modern animal nutrition. Developments during this period include the introduction of fundamental nutrients and the separation of feed into protein, fat, and carbohydrate components. In this respect, proximate analysis, a combination of analytical procedures devised more than 100 years ago by German scientists at the Weende Experiment Station (also known as Weende analysis), paved the way for estimating the nutrient content of feed samples. Although detailed knowledge of different analytical procedures is not required, familiarity with different basic feed analyses will enhance learning and understanding of animal nutrition.

Why Perform Nutrient Analysis of Feedstuffs?

Animal nutrition is the science of feed preparation (formulation) and feeding to meet the needs of animals at different phases of growth, or life stages. Therefore, nutritionists need to know the nutrient components of the feed or the raw materials used in ration formulation. Nutrient analysis serves as a system to analyze the feed and the needs of the animal, enabling producers to optimize nutrient utilization in feed and helping researchers relate to animal performance, tackle issues of underperformance, and reduce food production costs.

Reasons for Nutrient Analyses in Feed

Ration formulation and feeding
Trouble shooting

Sampling Feed for Analyses

Modern chemical methods and equipment need only a small amount of the feed (2 to 10 g) for analyses. Therefore, sample materials collected and prepared for analyses should represent the best reasonable estimate of the total feed fed to animals. Sample integrity during preparation (e.g., grinding, drying), storage (e.g., temperature), and transportation should be considered. The frequency of feed analysis depends on batches of feed made, variability of feed sources (e.g., cultivar, location of growth), and cost of analyses. Several core samples should be taken, combined, ground, and subsampled. Avoid taking a sample directly from outside of a bale (use common sense)! Weather patterns should also be considered, as they can affect the moisture content of the sample.

Analytical Methods

Traditionally, feedstuffs are subjected to different protocols of laboratory analyses (wet chemistry) for nutrient profiling. These analytical procedures are specific for a given element (e.g., N), compound, or group of compounds. Chemical methods often employ drastic degradation of the sample with different acids or other solvents and may not be true estimates of an animal’s ability to utilize them efficiently. However, considering the time and cost of other methods using live animals (e.g., explained in chapter 20) that provide more accurate estimates, laboratory analyses are used widely to get a head start.

Proximate Analysis

Proximate analyses are a combination of analytical procedures developed in 1865 by Wilhelm Henneberg and Friedrich Stohmann at the Weende Experiment Station in Germany. They are based on the elimination of water from the feed (as shown later) and then the determination of five proximate principles in the remaining dry matter (DM). They are as follows, and their names refer to specific proximate principles:

CRUDE PROTEIN
ETHER EXTRACT
CRUDE FIBER

The determination of dry matter (DM) is the most common procedure carried out in nutrition laboratories because plant feedstuffs may vary in water content. The amount of water content must be known to permit comparisons of different feeds.

DM is determined by drying the test material at 105° C overnight in an oven. DM is then determined by the following calculation:

dry weight / fresh weight (also called as-fed weight) * 100 = % DM.

Most feeds are around 90% DM, and silages are about 30% to 35% DM. Possible errors in DM analyses include loss of volatile fatty acids (VFAs), essential oils, lactic acid in silage, or any other fermented products. Moisture can also be determined by moisture meters, but results are not as precise as those obtained by drying testing materials in the oven. Freeze-drying or drying at lower temperatures can minimize errors.

The following is an example of DM calculation on a batch of corn silage samples:

Fresh (as-fed) weight = 2 kg

Dry weight = 0.7 kg

DM % = (0.7 kg/2.0 kg)*100 = 35%

A dry matter (DM) test estimates moisture.

The higher the DM, the lower the moisture.

Crude Protein (CP)

The procedure to estimate crude protein was developed by a Danish chemist, Johan Kjeldahl and is commonly known as “Kjeldahl” procedure. The Kjeldahl analysis depend on the measurement of nitrogen (N) in the test material. To convert the measured N content of the test material to crude protein, a calculation factor of 6.25 (N x 6.25) is applied. This is based on the fact that all proteins contain about 16% N(100/16 = 6.25) or 16 g of N comes from 100 g protein, or 1 g of N is associated with 100/16 = 6.25 g of protein.

NITROGEN (N) * 6.25 = CRUDE PROTEIN (CP)

The following is an example of crude protein calculation on a batch of soybean meal samples:

Nitrogen content = 7.35 g

Crude protein = 7.35 × 6.25 = 45.9 g

The Kjeldahl procedure measures nitrogen, not protein.

This process of nitrogen determination involves boiling the dried samples in 36 N sulfuric acid (H2SO4). This will convert nitrogen to ammonium sulfate ([NH4]2SO4). The mixture is then cooled and neutralized with 12 N sodium hydroxide (NaOH). This will release ionized ammonium. The sample is then distilled, and the distillate containing the ammonium is titrated with 0.02 N sulfuric acid. This analysis is accurate and repeatable but time consuming and involves the use of hazardous chemicals. The information obtained on N content and hence CP content is of limited use to nonruminants, such as pigs and poultry, as it does not indicate the quality of the protein, but it is applicable to ruminant animals that can efficiently utilize all forms of N.

A possible error in the Kjeldahl method is assuming all nitrogen presented in the sample is in protein form. This assumption is not necessarily true because nitrogen could be in nucleic acids (ribonucleic acid (RNA) or deoxyribonucleic acid (DNA)) or can exist as nonprotein nitrogen, such as urea.

Ether Extract

Ether-soluble materials in feed include different organic compounds that are soluble in organic solvents. In animal feeds, ether extract may include fats, fatty acid esters, and fat-soluble vitamins and hence are often referred to as crude fat. The primary goal of ether extracts is to isolate the fraction of the feedstuff that has a high caloric value. A portion of the dried feed sample is boiled in ether (organic solvent) for four hours. Since fats are soluble in ether, ether extract is equivalent to fat. Provided the ether extract contains fats and fatty acid esters, this approach is valid. However, in samples that contain high levels of other compounds soluble in organic solvents, such as plant waxes or resins, it may not give a true estimate of feed caloric value. However, this error is generally small in typical animal feedstuffs. Overall, this test does not indicate anything about the quality of the fat in the feed.

The Ether Extract procedure assumes substances soluble in ether are fats.

Ash is the residue remaining after all the organic nutrients have been burned off or oxidized completely in an oven at 500° to 600° C for two to four hours. Nutritionally, ash values have little importance, although high values may indicate contamination (e.g., soil) or dilution of the feed sample with limestone or salt. Ash values obtained are cumulative of all the mineral elements combined together. High temperatures used for burning may cause loss of some volatile elements such as chloride, zinc, selenium, iodine, and so on. Consequently, ash values can underestimate mineral contents. However, this error is small. Identifying individual minerals may be more meaningful and useful. If ash values are not very useful, why obtain them? They allow for calculations of nitrogen-free extract compared to DM (see later).

An ash test measures inorganic compounds in feed.

High ash values indicate feed contamination.

Crude Fiber

Crude fiber estimates the indigestible fraction of feed or those fractions of the feed that are fermented in the hindgut by microbes. Crude fiber includes different insoluble carbohydrates that are associated with the cell wall of plants and are resistant to the action of digestive enzymes. Crude fiber is made up of plant cell structural components, including cellulose, hemicellulose, lignin, and pectin. For nonruminant animals, crude fiber is of little value energy-wise. However, it is important for maintaining hindgut health and microbial population. Crude fiber is important in the diets of ruminant animals, which can ferment a large portion of it. Crude fiber is described in detail below.

Crude fiber measures fermentable components of the feed. Crude fiber has little energy value but is important for gut health in pigs and poultry. Ruminant animals can ferment a large portion of crude fiber.

To determine crude fiber in feed, a sample is dried, boiled in weak sulfuric acid (1.25% H2SO4), and filtered. The residue is boiled in a weak alkali (1.25% NaOH) and filtered, and the remaining residue is dried and ashed. The difference between the filtered dried sample and ash is crude fiber. The two boiling processes simulate the pH conditions of the digestive tract, acidic in the stomach and alkaline in the small intestine. However, the enzymatic digestion in the digestive tract is not simulated in the procedure.

Crude fiber tests underestimate true fiber in feed.

A major problem with this procedure is that the acid and base solubilize some of the true fiber (particularly hemicellulose, pectin, and lignin), and some cellulose is partially lost too. Hence crude fiber underestimates true fiber in the test material. The number, or value, obtained in this procedure, therefore, is practically meaningless. Most laboratories have phased out the crude fiber term and replaced it with the detergent fiber system (discussed in detail later)

Nitrogen-Free Extract

The term nitrogen-free extract (NFE) is a misnomer, as there is no nitrogen or extraction process in this procedure. Nitrogen-free extract is not determined analytically in the laboratory, as shown below. NFE supposedly represents the soluble carbohydrates of the feed, such as starch and sugar, and is the difference between the original sample weight and the sum of the weights of moisture (water), ether extract, crude protein, crude fiber, and ash. Therefore, it accumulates the errors of the other analytical systems. It is an overestimate of true NFE.

% NFE = (% DM − (% ether extract + % crude protein + % ash + % crude fiber) Nitrogen-free extract is a calculated value and not an analyzed value.

“All Fibers Are Not Created Equal”

Peter J. van Soest (1982) improved methods of crude fiber analyses into the detergent fiber system . The concept behind the detergent fiber system is based on the fermentability or digestibility of fiber. Accordingly, plant cells can be divided into cell walls (which contain hemicellulose, cellulose, and lignin and are less digestible) and cell contents (which are mostly digestible, such as starch and sugars) (shown below in detail).

Use of these methods allows plant components to be divided into neutral detergent fiber (NDF) and acid detergent fiber (ADF).

The detergent fiber system includes neutral detergent fiber and acid detergent fiber.

NDF contains the major cell wall components, such as cellulose, hemicellulose, and lignin. It may also contain other very important components, such as cutin, and some proteins too. Hemicellulose, cellulose, and lignin are indigestible in nonruminants, while hemicellulose and cellulose are partially digestible (fermentable) in ruminants.

NDF fractionation is determined by boiling feed samples for one hour in a solution containing sodium lauryl sulfate and ethylene diamine tetra acetic acid (EDTA) at pH 7.0. This detergent extracts soluble components of the feed (protein, sugars, lipids, and organic acids), and the nonsoluble material is called NDF.

NDF = Hemicellulose + Cellulose + Lignin

Acid detergent fiber is an estimate of cellulose + lignin in the feed sample. Hemicellulose, therefore, is estimated as NDF − ADF. This is not a perfect system, as there are contaminants in both ADF and NDF terms. ADF does the best job of describing the portion of feed it is designed to estimate (i.e., cellulose + lignin). The ADF and NDF terms have now largely replaced the crude fiber term. By using this method, we can better predict the digestibility of forages for animals. Nowadays, most laboratories use NDF and ADF analysis instead of crude fiber.

The broad classifications of nutrients are water, protein, fat, carbohydrate, minerals, and vitamins. These classifications are so broad that analysis of these has limited value.
For analysis, feed should be sampled as many times as possible and then dried, ground, and mixed for subsampling.
Drying is used in the first step of proximate analysis to determine the water content of a feedstuff. Some components of a feed may be lost through volatilization at this time. Usually, this is a small error.
To reduce damage to feed, alternatives to drying include freeze-drying or drying at lower temperatures (i.e., 55° C)
Ether extract (EE) is determined by extracting the dried sample in organic solvent (ether). It represents the fat content in the sample. It assumes all the substances soluble in ether are fat, which is not true.
Crude protein (CP) is determined by the Kjeldahl method. It analyzes the N content of a diet and calculates protein using the assumption that all protein is 16% N. The problems with this are that some proteins are not 16% N and some feed constituents that contain N (i.e., urea, DNA, RNA) are not proteins.
Ash is used to determine mineral content. It provides no information on actual amounts of individual minerals. It provides an estimate of the total inorganic component of the diet, which is often interpreted as contamination. Many feed tags indicate a maximum limit for ash as an index of quality.
Crude fiber (CF) is an estimate of the cell wall constituent of a feed. Ideally, it should represent cellulose, hemicellulose, and lignin; however, the process of digesting feed with weak acid then weak base solubilizes some of these components (especially lignin and hemicellulose), and as a result, CF underestimates true fiber. It is the major limitation of the proximate analysis system.
Nitrogen-free extract (NFE) is designed to provide an estimate of water-soluble polysaccharides (sugars, starch) and is calculated by the difference between the original sample weight and the sum of weights of moisture (water), ether extract, crude protein, crude fiber, and ash. Therefore, it accumulates the errors of the other analytical systems. It is an overestimate of true NFE.
Van Soest developed improved methods of fiber analyses (the detergent fiber system). Acid-detergent fiber (ADF) is an estimate of cellulose + lignin, whereas neutral detergent fiber (NDF) is an estimate of cellulose + hemicellulose + lignin. Hemicellulose therefore is estimated as NDF − ADF. This is not a perfect system, as there are contaminants in both ADF and NDF terms. ADF does the best job of describing the portion of feed it is designed to estimate (i.e., cellulose + lignin). The ADF and NDF terms have now largely replaced the crude fiber term.

Review Questions

How would you define “nutrition”?
Why is nutrition important in today’s livestock production?
What are the six major classes of nutrients?
Proximate analysis of a feed includes the following tests:
Ether extract is determined by extracting the dried sample in organic solvent (ether). It represents which component of the feed sample?
Remains the same
Crude protein
Crude fiber
Nitrogen free extract
Ether extract
7.0 – 6.25
Hemicellulose
Differentiate between neutral detergent fiber (NDF) and acid detergent fiber (ADF).

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Nutrition in Animals

Nutrition is a factor that is important for all living beings. For animals and plants also, it is important for their survival. Through the process of photosynthesis, plants prepare their own food but animals cannot prepare their food and therefore are dependent on plants or other animals for their food.

Animals fulfill their nutritional needs either by eating plants directly (herbivores) or indirectly by eating animals that have consumed plants (carnivores). Animals that depend on both plants and animals; are termed as omnivores. For proper growth and survival, all the organisms require food irrespective of the source they derive from their food.

Feeding Habits of Animals

Feeding habits of animals provide them their adequate nutrition which they intake by the process called Ingestion. The method of ingestion differs in different animals. For example- Nectar is the source of food for bees and hummingbirds, python tends to swallow its prey, and the grass is being ingested by cattle.

Different feeding habits of animals lead to an Evolution. The earliest forms were large amphibians that ate fish among the terrestrial animals. While amphibians like frogs fed on small fish and insects, the reptiles began feeding on other animals and plants.

Evolution of form and function is caused by the specialization of organisms towards specific food sources and of course specific ways of eating.

For instance, the difference in mouthparts and teeth in whales, mosquitos, tigers, and sharks or distinct forms of beaks in birds, such as in hawks, woodpeckers, pelicans, hummingbirds, and parrots are a perfect example of adaptation to different types of eating by these animals.

Animals can be divided into the following groups depending upon their food habits:

Herbivores: Animals that depend upon plants and fruits for their nutrition are called Herbivores. Cows, goats, sheep, buffaloes, etc. are herbivores.

Carnivores: Carnivores are animals that depend upon other animals for food. Lion, tigers, wolfs are some of the carnivores.

Omnivores: These include organisms that eat both plants and animals. Humans, bear, dogs, crow are omnivores.

Types of Nutrition in Animals

The different types of nutrition in animals include:

Filter Feeding: It is a process of acquiring nutrients from particles suspended in water. This method is commonly used by fish.

Deposit feeding: It is the process of obtaining nutrients from particles suspended in the soil. Earthworms use this method to take nutrition.

Fluid feeding: When one animal obtains nutrients by consuming other organisms’ fluids. Honey bees, mosquitos follow this mode of food intake.

Bulk feeding: Eating whole organisms and grabbing nutrients from it.

Ram feeding and suction feeding: Consuming prey as food via the fluids around it. This mode of ingestion is usually adopted by aquatic animals such as bony fish.

Process of Nutrition in Animals

The process of nutrition in animals are as follows -

Ingestion is the process of taking in food.

In this process, the larger food particles are broken down into smaller, water-soluble particles. There are physical or chemical for digesting food.

The digested food is absorbed in the bloodstream through the intestinal wall.

Assimilation

The absorbed food is used for energy, growth and repair of the cells of the body.

The undigested food is removed out of the body in the faeces. This process is known as egestion.

Nutrition in Simple Animals

Amoeba ingests its food with the help of pseudopodia.

The food is engulfed by forming a vacuole and is digested with the help of digestive enzymes.

The digested food is absorbed directly into the cytoplasm by the process of diffusion.

Energy is obtained from the absorbed food that helps in its growth.

The undigested food is egested out of the body of amoeba by rupturing the cell wall.

FAQs on Nutrition in Animals

1. Why is Nutrition important for animals?

Nutrition helps in proper growth and maintenance of the cells. It provides energy to carry out different life processes.

2. What are the types of Nutrition in Animals?

Deposit Feeding: It is the process of obtaining nutrients from particles suspended in the soil. Earthworms use this method to take nutrition.

Fluid Feeding: When one animal obtains nutrients by consuming other organisms’ fluids. Honey bees, mosquitos follow this mode of food intake.

Bulk Feeding: Eating whole organisms and grabbing nutrients from it.

3. What is the process of Nutrition intake in animals?

The process of nutrition in animals are as follows -

In this process, the larger food particles are broken down into smaller, water-soluble particles. There are physical or chemical for digesting food.

4. What are the different types of animals as per their Food Habits?

Biology • Class 7

Animal Nutrition

Scientific papers.

Maize green forage as a partial replacement for lettuce in the diet of West Indian manatee Trichechus manatus (Krajda et al., 2023)

October 2023

A study in JZAR described how the diet of a group of zoo-housed West Indian manatees was changed with the introduction of maize green forage as partial replacement for lettuce: ✔ Introduction of maize green forage increased concentration of dry matter and fibre in diet, while reducing crude protein . ✔ Due to reduced cost of maize green forage in comparison to lettuce, the zoo saved approximately € 60,000 in three years. ✔ Maize green forage may be a suitable option for captive manatees, with potential health benefits and a reduction in feeding costs for the zoo.

Multi-criteria study on a change to a fruit-free diet in Cebidae and Cercopithecidae (Viallard et al., 2023)

The effects of gradually removing fruit from the diets of five zoo-housed primate species (spider monkeys , Hamlyn monkeys, L’Hoest monkeys, Roloway monkeys, and yellow-breasted capuchins) were monitored in a study published in JZAR : ✔ Lower sugar and higher fibre achieved with new diet. ✔ Hamlyn monkeys showed improved faeces consistency and spent more time feeding with new diet. ✔ Spider monkeys also showed an improvement in faeces consistency , while capuchins spent more time feeding. ✔ Further evidence of the potential benefits of fruit-free diets in zoo-housed primates.

Fasted and furious? Considerations on the use of fasting days in large carnivore husbandry (Kleinlugtenbelt et al., 2023)

A study published in the JZAR surveyed the husbandry guidelines and feeding regimes of large carnivores in 44 European zoos: ✔ Husbandry guidelines did not state that fasting days should be preceded by gorge-feeding. ✔ Feeding regimes should be re-assessed to ensure large carnivores are gorge-fed (with satiety and gut extension) before fasting days. ✔ Feeding should be associated with high physical activity and cognitive challenges to better mimic natural feeding behaviours.

The behavioural effects of feeding lean meat vs whole rabbit carcasses to zoo jaguars Panthera onca (Enemark et al., 202 3)

How does the behaviour of zoo-housed jaguars differ when fed lean meat VS whole rabbit carcasses ? A case study on three jaguars, published in Journal of Zoo & Aquarium Research , investigated: ✔ Feeding-related behaviours increased b y over 300% when fed whole carcasses - particularly in the first hour after food was presented. ✔ Despite this increase, difference accounted for less than 1% of daily time budget. ✔ Future studies can further investigate the impact of larger carcasses on the behaviour of this species in human care.

Nutritional effect of feeding enrichment using bamboo Pleioblastus spp. in zoo-kept Asian elephants Elephas maximus ( Tsuchiya et al., 2023)

Bamboo is often used as enrichment for zoo-housed herbivores, but does it have negative effects on nutrition ? This was investigated in a study in the JZAR , focusing on four Asian elephants (4 - 8 years old): ✔ Diet with bamboo : portion of sudangrass hay replaced with bamboo (~20% of diet). ✔ No significant differences between diets in nutritional intake, digestibility or blood condition. ✔ Bamboo did not seem to affect the nutritional status of the elephants: applications to ex situ management.

Diet impacts the structure and function of the bacterial community in the gastrointestinal tract of a sloth bear (Loudon et al., 2022)

October 2022

A research paper in the latest issue of Journal of Zoo Aquarium Research tested the effects of a new diet , lower in dietary starch, on the gastrointestinal tract of a zoo-housed sloth bear : ✔ Under new diet: bacterial community richness did not change BUT the relative abundance of some bacterial taxa did.

✔ Evidence of increased protein digestion, amino acid fermentation and pH, and decreased acetate to propionate ratio found in faeces. ✔ Results suggest the need to better match the diets of captive sloth bears with their wild counterparts.

Effects of Storage Time and Thawing Method on Selected Nutrients in Whole Fish for Zoo Animal Nutrition (Gimmel et al., 2022)

Are the nutrients in whole fish affected by storage time and thawing method? A study in Animals looked into it: ✔ Three thawing methods tested: refrigerator, room temperature, running water; ✔ Vitamin B1 was below detection limits in most analysed samples of two of the fish species; ✔ Significant decrease in Vitamins A , D3 and E after six-month storage; ✔ More research recommended on the effects of thawing method; ✔ Recommendations for zoo animal nutrition: vitamins B1 and E supplementation , and avoid storing fish for more than six months.

Dietary protein requirement for captive juvenile green turtles ( Chelonia mydas ) (Jualaong et al., 2022)

The protein requirements of juvenile green turtles , part of a head-starting programme, were investigated in a study in Zoo Biology :

✔ 45 turtles put in different tanks, in groups of 3 , and fed diets with different protein %; ✔ Highest growth performance & feed utilisation in turtles on diet with 40% protein; ✔ Calcium deposition & phosphorus also improved under this diet, supporting healthy bones & hard carapace; ✔ Estimated optimal protein level: 40.6% .

Feeding regimen and growth comparison in two related African painted dog Lycaon pictus litters (Cloutier et al., 2022)

A study in Journal of Zoo & Aquarium Research compared growth in two related captive African painted dog litters under different feeding regimes : ✔ One litter was fed freely while the other was fed at regular intervals; ✔ Growth differences in: hind leg/body length ratios, front and hind leg/body length differentials, and mean body mass; ✔ No differences in body length, ear height, head circumference, and muzzle length. ✔ Small sample size but interesting findings that call for further research on the topic.

Keeping the golden mantella golden: The effect of dietary carotenoid supplementation and UV provision on the colouration and growth of Mantella aurantiaca (Newtons-Youens, Michaels & Preziosi, 2022)

How to maintain the bright colouration of golden mantellas in captivity? A new study in Journal of Zoo & Aquarium Research investigated whether carotenoid supplementation & UV provision had an effect on it:

✔ An enhanced carotenoid diet and UVB light provision both increased colouration - more so when provided separately than in combination; ✔ Frogsi in a "red diet" showed a more intense red colouration than those in a "yellow diet" (same carotenoid concentration, but different profile). ✔ Both concentration and profile of carotenoids influence colouration of golden mantellas.

Assessment of Feeding Behavior of the Zoo-Housed Lesser Anteater ( Tamandua tetradactyla ) and Nutritional Values of Natural Prey (Zárate et al., 2021)

January 2022

A paper in JZBG looked into the behaviour of zoo-housed lesser anteaters when fed live ants & termites :

✔ Anteaters consumed more termites & spent more time feeding on them than ants;

✔ Ant meal = higher protein and lipids ;

✔ Termite meal = higher carbohydrate digestibility ;

✔ Insect consumption may be associated with nutritional and digestibility values.

New insights into dietary management of polar bears ( Ursus maritimus ) and brown bears ( U. arctos ) (Robbins et al., 2021)

November 2021

New paper in Zoo Biology looked into the diets of polar bears & brown bears :

✔ Both wild & captive bears select diets with low protein and higher fat or digestible carbohydrate concentration;

✔ Captive bears are often fed high-protein diets, which may be associated with their susceptibility to renal failure & liver cancer ;

✔ Diets of captive polar & brown bears should be reviewed to better match their preferred macronutrients ratios.

Colony composition and nutrient analysis of Polyrhachis dives ants, a natural prey of the Chinese pangolin ( Manis pentadactyla ) (Xu et al., 2021)

October 2021

A study in Zoo Biology analysed the nutritional contents & composition of a colony of Polyrhachis dives ants - key prey in the diet of the critically endangered Chinese pangolin:

✔ Colony consisted mostly of adults, but also pupae, larvae & eggs;

✔ High protein & chitin, low fat & formic acid identified in both colony & adult ants;

✔ Colony & adult ants differed in several aspects of chemical composition - diet of captive pangolins shouldn't be composed solely by adult ants as they prey on all colony in the wild;

✔ Applications to husbandry and nutrition of captive Chinese pangolins.

Investigating food preference in zoo-housed meerkats (Brox et al., 2021)

A study in Zoo Biology looked into food preferences in zoo-housed meerkats:

✔ Clear, stable preference hierarchy identified;

✔ High in preference hierarchy: Cooked eggs & raw meat;

✔ Lower in preference hierarchy: Vegetables;

✔ Slight differences between juveniles & adults;

✔ Applications to zoo management and welfare assessments.

A modified diet to support conservation of the Atala hairstreak butterfly ( Eumaeus atala Poey) (Braatz et al., 2021)

A study in Zoo Biology investigated the suitability of a freeze-dried diet in a captive breeding programme for the Atala hairstreak butterfly:

✔ Smaller larvae fed freeze-dried leaves & stems from host plant;

✔ Larger larvae switched to live-plant diet;

✔ Highly successful method: over 3400 individuals released into the wild;

✔ Freeze-dried diet is appropriate substitute when live plant is scarce or not available - potential applications to other butterfly species.

Ensiling of maple leaves and its use in winter nutrition of mantled guereza ( Colobus guereza ) (Lasek et al., 2021)

A paper in Zoo Biology evaluated the composition and nutritional value of maple leaf silage and its suitability for inclusion in the winter diets of captive mantled guerezas:

✔ Most nutrients were unaffected by ensiling process;

✔ Mantled guerezas promptly fed on maple leaf silage.

✔ Higher nutrient intake when maple leaf silage included in diet;

✔ Ensiling, with or without additives, effectively conserved maple leaves.

Grading fecal consistency in an omnivorous carnivore, the brown bear: Abandoning the concept of uniform feces (De Cuyper et al., 2021)

February 2021

A study in Zoo Biology graded faecal consistency in nine zoo-housed brown bears fed a variety of diets:

✔ Six-point scale established for uniform faeces;

✔ Additional grading system for faeces with dual consistencies (observed in 11% of all faeces);

✔ More vegetation or whole prey seemed to be associated with firmer faeces;

✔ Faecal consistency is affected by diet in this species and can be used for gut health monitoring.

Circulating nutrients and hematological parameters in managed African elephants ( Loxodonta Africana ) over a 1‐year period (Wood et al., 2020)

A study published in Zoo Biology investigated the circulating nutrients and hematological parameters in zoo-housed African elephants, over a one-year period:

✔ Seasonal changes in circulating nutrients;

✔ African elephants fed mixed feedstuff & fortified pellet diets may not need Vitamin E supplementation.

✔ Assessment of circulating nutrients provides evidence for better elephant management in captivity.

Daily lettuce supplements promote foraging behavior and modify the gut microbiota in captive frugivores (Greene et al., 2020).

A study in Zoo Biology i nvestigated the effects of daily lettuce supplements on the behaviour and gut microbiota of captive ruffed lemurs:

✔ The lemurs (especially younger individuals) consistently foraged on the lettuce during the study period;

✔ Enrichment of potentially-beneficial microbes in the guts;

✔ Lettuce provision is potentially beneficial to captive frugivores.

Dietary management of hypercholesterolemia in a bachelor group of zoo-housed Slender-tailed meerkats ( Suricata suricatta ) (Dobbs et al., 2020)

October 2020

Captive meerkats are prone to high cholesterol levels, which can lead to health problems. A study in JZAR investigated the impact of a new diet on cholesterol levels in a group of zoo-housed meerkats:

✔ New diet with lower saturated fat & cholesterol implemented;

✔ Reduction of cholesterol levels in all individual meerkats;

✔ Good body condition score & weight reported after new diet introduction.

Photo credit: Twycross Zoo

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Conserv Physiol
v.5(1); 2017

Nutritional physiology and ecology of wildlife in a changing world

Kim birnie-gauvin.

1 Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental Science, Carleton University, 1125 Colonel By Drive, Ottawa, , Canada ON K1S 5B6

2 DTU AQUA, National Institute of Aquatic Resources, Section for Freshwater Fisheries Ecology, Technical University of Denmark, Vejlsøvej 39, 8600 Silkeborg, Denmark

Kathryn S. Peiman

David raubenheimer.

3 Faculty of Veterinary Science, The University of Sydney, Regimental Drive, Camperdown, NSW 2050, Australia

Steven J. Cooke

Editor : Craig E. Franklin

Humans have modified planet Earth extensively, with impacts ranging from reduced habitat availability to warming temperatures. Here we provide an overview of how humans have modified the nutritional physiology and ecology of wild organisms, and how nutrition is vital to successful conservation practices.

Over the last century, humans have modified landscapes, generated pollution and provided opportunities for exotic species to invade areas where they did not evolve. In addition, humans now interact with animals in a growing number of ways (e.g. ecotourism). As a result, the quality (i.e. nutrient composition) and quantity (i.e. food abundance) of dietary items consumed by wildlife have, in many cases, changed. We present representative examples of the extent to which vertebrate foraging behaviour, food availability (quantity and quality) and digestive physiology have been modified due to human-induced environmental changes and human activities. We find that these effects can be quite extensive, especially as a result of pollution and human-provisioned food sources (despite good intentions). We also discuss the role of nutrition in conservation practices, from the perspective of both in situ and ex situ conservation. Though we find that the changes in the nutritional ecology and physiology of wildlife due to human alterations are typically negative and largely involve impacts on foraging behaviour and food availability, the extent to which these will affect the fitness of organisms and result in evolutionary changes is not clearly understood, and requires further investigation.

Introduction

In the last century, humans have modified the global landscape to accommodate the growing human population ( Vitousek et al. , 1997 ). Previously pristine landscapes, riverscapes and seascapes have been transformed as a result of agriculture, urbanization, resource extraction (e.g. mines, forestry, fishing), energy production (e.g. hydropower, fossil fuels), military activity, and other human developments and activities ( Marzluff et al. , 2001 ; Foley et al. , 2005 ; Dudgeon et al. , 2006 ; Kennish, 2002 ; Crain et al. , 2009 ). The accumulation of human-induced changes has modified ecosystems to the point where human activities are now considered the primary driver of global change ( Vitousek et al. , 1997 ; Sanderson et al. , 2002 ) and it is proposed that we have entered a new epoch called the Anthropocene ( Crutzen, 2006 ). As a result, humans have changed the environment in which wild animals live, including the abundance and quality of food items which has implications for animal health, reproduction and survival ( Acevedo-Whitehouse and Duffus, 2009 ).

In recent years, two fields of nutrition have grown significantly ( Frost et al. , 2014 ). Nutritional ecology investigates the relationships among diet, digestive physiology and feeding behaviour ( Foley and Cork, 1992 ; Raubenheimer et al. , 2009 ), while nutritional physiology focuses on the subset of relationships related to the intake and assimilation of food items. Here we focus on how food choices and digestion are affected by the abundance (quantitative limitation) and composition (qualitative limitation) of the foods available in a particular environment ( Lambert, 2007 ; see Table 1 for commonly used tools to evaluate nutrition in animals). These fields have generated many insights that have made them a cornerstone for understanding the mechanisms that link ecological patterns and processes to animal phenotypes ( Raubenheimer et al. , 2009 ; Karasov et al. , 2011 ; Simpson and Raubenheimer, 2012 ). They are also important in understanding the constraints that nutrition may impose on locomotion, activity patterns, demography and population dynamics ( Foley and Cork, 1992 ; Raubenheimer et al. , 2015 ).

Brief summary of the common methods used to study nutrition in animals, with a description of the advantages and disadvantages for each

Method	Pros	Cons
Gut sampling	Provides insight into specific ingested prey items, nutrient intake, energetic intake	Insight into short-term diet only; Ingested organisms may be mistaken during identification; Typically requires lethal sampling or high levels of induced stress (stomach lavage) but new options with DNA assessment of gut materials are being developed
Tissue sampling	Provides insight into macromolecules	Often requires lethal sampling
Faecal analysis	Non-invasive, does not require capture, or lethal sampling	Difficult to match faeces to a particular individual if behaviour is important to the study; Soft-bodied prey often not identifiable
Stable isotopes	Provides insight into short and long-term diet	Costly; Does not provide information on specific ingested foods
Direct behavioural observations	First hand observations of what foods are ingested	Very time-consuming; Human presence can sometimes alter feeding behaviour
Bio-logging or biotelemetry	Provides information on the spatial and temporal patterns of foraging behaviour and food intake	Data may take time to examine; Electronic tags tend to be expensive

Currently there is no cohesive framework that posits how human-induced environmental change influences the nutrition of wild vertebrates. Such a framework would be particularly useful for developing testable hypotheses concerning the future implications of such alterations. In this paper, we present an overview of the ways in which humans have altered the environment (climate change, pollution, habitat loss/fragmentation, invasive species, human disturbances and provisioned food sources), and consider how each of these modifications may affect the acquisition, availability (quality and quantity) and digestion of food for vertebrates. We additionally present representative examples that demonstrate the extent to which humans can impact the nutrition of wild vertebrates. We address how nutrition has been used in the context of in situ and ex situ conservation. We focus on vertebrates given their imperilled status ( Sala et al. , 2000 ), interest from conservation practitioners and policy makers ( Redford et al. , 2011 ) and because relative to most invertebrates, the basic biology, natural history and nutritional ecology of vertebrates are well studied (see Donaldson et al. , 2016 ), an understanding owing in large part to them being commonly held in zoos and aquaria ( Conde et al. , 2011 ).

Human-induced environmental changes and their effects on nutrition

Humans have altered the planet in many ways including through climate change, pollution, habitat alteration and the introduction/translocation of new species (reviewed in Vitousek et al. , 1997 ). What does this mean to animals in terms of nutrition?

Climate change

In today’s warming world, shifts in moisture, carbon dioxide, temperature and solar radiation are pervasive ( IPCC, 2013 ), and these changes will directly and indirectly affect animal performance by influencing the composition of their food ( Post and Stenseth, 1999 ; Kearney et al. , 2013 ; Rosenblatt and Schmitz, 2016 ). These predicted changes are far-reaching and complex, and their interactions among trophic levels are still poorly understood. For example, changes to primary producers involve both quality and abundance: increased temperature may lead to increased stratification of the water column in parts of the ocean, creating nutrient limitation and changing the dominant species of phytoplankton with unknown effects on higher trophic levels ( Beardall et al. , 2009 ); and Lake Tanganyika in Africa has already undergone decreases in phytoplankton productivity due to increased stratification from a combination of increased temperature and decreased wind velocity, leading to a decline in pelagic fishes ( O’Reilly et al. , 2003 ). On land, elevated CO 2 typically causes an increase in tissue carbon in plants, accompanied by decreases in nitrogen ( Cotrufo et al. , 1998 ), phosphorus ( Gifford et al. , 2000 ) and other elements ( Loladze, 2002 ), including protein ( Robinson et al. , 2012 ). When feeding on these plants, insects had decreased growth but increased consumption ( Robinson et al. , 2012 ) indicating that the nutritional quality of the plants had diminished. Food protein content is often associated with animal performance, and so a decrease in the ratio of protein energy to non-protein energy (i.e. protein vs carbohydrates and lipids; Raubenheimer et al. , 2014 ) will reduce the quality of plant foods available to wildlife ( Zvereva and Kozlov, 2006 ). Plants may also undergo increases in toxic secondary compounds under increased temperatures which may affect the ability of herbivores to meet their nutritional requirements ( Moore et al. , 2015 ). Most of these changes have been documented for the primary producers themselves, with much less research on the subsequent nutritional effects on their consumers.

Climate change can also directly impact secondary and tertiary consumers in several ways. One way it does this is to cause further physiological impairments when combined with decreased nutritional intake ( Robbins, 1993 ; Murray et al. , 2006 ). For example, when prey is depleted and individuals catabolize their fat reserves, lipophilic toxins such as PCBs can be released ( Jepson et al. , 2016 ). In herbivores, body condition influences how individuals choose locations of high forage quality versus tolerable thermal stress ( Long et al. , 2014 ). These trade-offs may be particularly severe during the energy-intensive time of reproduction (egg or embryo development in females, pregnancy or lactation in female mammals, and/or parental care) ( Lewis, 1993 ; Ashworth et al. , 2009 ) or be more intense in animals with certain reproductive strategies (e.g. income versus capital breeders; Costa, 2012 ). For example, nest success in parental male smallmouth bass ( Micropterus dolomieu ) is affected by both body size and climatic indices ( Suski and Ridgway, 2007 ). Because the activity and development of many insects depend on climatic conditions ( Burles et al. , 2009 ), food availability for insectivores will likely be highly affected by climate change ( Sherwin et al. , 2013 ; Berzitis et al. , 2017 ). As lower trophic levels can adapt their phenologies in response to climate change faster than their consumers can, shifts in peak abundance of food may no longer align with periods of vertebrate offspring growth and development ( Davies and Deviche, 2014 ). Additionally, when nutrient dispersers such as bats are affected by climate change, this will presumably affect the extent to which nutrients will be dispersed over the landscape, potentially having important repercussions on other animals, though this link has not yet been investigated.

Changes in animal behaviour can occur at concentrations of chemicals lower than can cause mortality ( Little and Finger, 1990 ) and may affect foraging decisions ( Scott and Sloman, 2004 ; Vaughan et al. , 1996 ). Environments that are heavily contaminated by metals have a reduced abundance and diversity of many terrestrial insects (reviewed in Heliövaara and Väisänen, 1990 ), which can affect the breeding performance of insectivorous birds ( Eeva et al. , 1997 ). Birds exposed to metal pollutants also showed decreased appetite ( Di Giulio and Scanlon, 1984 ) and paper mill effluents interfere with digestive enzymes in fish ( Temmink et al. , 1989 ). Thus, pollutants potentially have accumulating effects: they reduce the food supply available, decrease interest in the available food and reduce digestion of food that is consumed. Predators are especially vulnerable because many compounds undergo bioaccumulation, exposing animals higher in the food chain to elevated levels of pollutants ( Walker, 1990 ).

In streams, lakes and estuaries, water can become turbid through a variety of processes ( Smith, 1990 ). This results in changes in the abundance and diversity of primary producers ( Smith, 2003 ) and affects the ability of consumers to detect prey ( Utne-Palm, 2002 ; Chivers et al. , 2013 ; Chapman et al. , 2014 ). In general, turbidity is predicted to affect piscivorous fish more than planktivorous fish due to differences in attack distances ( De Robertis et al. , 2003 ) but turbidity also changes the behaviour of prey fish due to decreased risk of predation ( Pangle et al. , 2012 ). For example, under turbid conditions perch ( Perca fluviatilis ) had reduced capture rates of benthic prey and slower growth rates ( Ljunggren and Sandstrom, 2007 ), and brown trout ( Salmo trutta ) consumed a lower diversity and abundance of benthic prey and had lower condition ( Stuart-Smith et al. , 2004 ). In planktivores, bluegill sunfish ( Lepomis macrochirus ) showed reduced feeding rates under increased turbidity ( Gardner, 1981 ); larval herring ( Clupea harengus pallasi ) increased feeding on plankton at low turbidity but decreased feeding at high turbidity ( Boehlert and Morgan, 1985 ); and perch captured fewer zooplankton with increasing turbidity while no effect was seen in roach ( Rutilus rutilus ) ( Nurminen et al. , 2010 ). Turbidity can also change prey selection. Piscivorous, benthivorous and planktivorous species have all showed shifts in prey composition in turbid environments ( Hecht, 1992 ; Stuart-Smith et al. , 2004 ; Shoup and Wahl., 2009 ; Johansen and Jones, 2013 ). Turbidity has clear effects on foraging behaviour and diet quantity and composition, but the fitness effects of these changes are not known.

Plastic debris accounts for 60–80% of the total debris in marine environments, coming from accidental equipment loss, careless handling (e.g. land-based trash washing to sea) and littering (reviewed in Derraik, 2002 ; Galgani et al. , 2015 ) but freshwater habitats also have large plastic debris loads ( Wagner et al. , 2014 ). Such pollution can greatly reduce the quantity of food that organisms can eat through a reduced ability to move (entanglement or injury) or a blockage of the digestive system (ingested debris) ( Quayle, 1992 ; Laist, 1997 ; Wilcox et al. , 2015 ; Holland et al. , 2016 ). Ingested debris can result in a reduction of the area available for nutrient absorption in animals ranging from sea turtles ( McCauley and Bjorndal, 1999 ; Schuyler et al. , 2016 ) to stickleback ( Katzenberger, 2015 ) to beachhoppers ( Platorchestia smithi ) ( Tosetto et al. , 2016 ) and can create a physical blockage of the digestive tract ( Danner et al. , 2009 ) which impedes further food intake and digestion. The accumulation of debris on the seafloor ( Galgani et al. , 2015 ) may also reduce the productivity and species composition of plants and prey items (reviewed in Kuhn et al. , 2015 ). Overall, plastics more commonly affect the ability of individuals to eat sufficient amounts of food rather than affecting the quality of food available, but the impact of plastics on trophic linkages has been identified as a global research priority ( Vegter et al. , 2014 ).

Habitat quantity and quality

Humans have altered landscapes extensively, causing habitat loss and fragmentation, which leads to changes in the physical environment and biogeography of plants and animals (reviewed in Saunders et al. , 1991 ). Because some species are restricted in the habitats they can occupy or type of food they can consume, these landscape modifications can severely reduce their population sizes, therefore restricting the abundance of prey for their predators. For example, habitat fragmentation can cause a decline in pollination and seed set ( Rathcke and Jules, 1993 ), thereby reducing the abundance of certain plant species and presumably affecting the herbivores that feed on them. Additionally, when animals choose habitats based on cues that are no longer appropriate, they experience an ecological trap and may undergo population declines ( Schlaepfer et al. , 2002 ). In general, specialist species are likely to be affected by habitat modification to a greater extent than generalist species ( Devictor et al. , 2008 ). However, some species are able to switch to foods that are more readily available when their preferred food source is scarce ( Felton et al. , 2009 ), suggesting that behavioural plasticity is an important factor to consider in order to fully understand the impacts of habitat alteration on animal nutrition ( Tuomainen and Candolin, 2011 ). Other modifications to the landscape can also affect the nutrition of wildlife. For example, fires are controlled in many areas, but burning can increase the quality of grass species for herbivores ( Hobbs and Spowart, 1984 ). Humans have also modified the land to accommodate infrastructures in order to meet anthropogenic needs (e.g. oil well sites, hydroelectric dams, roads). Such infrastructure reduces population size by replacing natural habitat and causing animals to avoid those areas (e.g. reindeer: Nellemann et al. , 2003 ; bears: Gibeau et al. , 2002 ; amphibians; Hamer and McDonnell, 2008 ; birds and mammals: Benitez-Lopez et al. , 2010 ), consequently reducing food abundance for their predators.

Some regions of the world have been depleted of their native vegetation by 93% and this has been replaced by agricultural land ( Saunders et al. , 1990 ), thereby providing crops as an alternative food source. Some crops are nutritionally attractive to wild animals and provide both energy ( Sukumar, 1990 ; Riley et al. , 2013 ; McLennan and Ganzhorn, 2017 ) and minerals ( Rode et al. , 2006a ). However, the effects on the health of these species are poorly studied. In contrast, the availability of grain crops in the winter for several species of geese has provided an excellent food source ( Gates et al. , 2001 ; Ely and Raveling, 2011 ) though some crop types are deficient in nutrients ( Alisauskas et al. , 1988 ). Thus the effects of replacing native vegetation with alternative food sources are still not known for most herbivores.

Invasive species

Human-caused habitat disturbance has been associated with an increased likelihood of invasion of communities by non-native species ( Hobbs and Huenneke, 1992 ), such as large oil well sites which increase the presence of non-native plants ( Preston, 2015 ). Some now invasive species were even purposely planted as food for wildlife ( Kaufman and Kaufman, 2007 ), even though native plants are often nutritionally better for herbivores than introduced species ( Applegate, 2015 ). Biological invasions contribute to the worldwide decline in biodiversity by changing the abundance and richness of communities ( Clavero and García-Berthou, 2005 ). This alters prey abundance, but the direction of this effect will depend on whether invaders affect common or rare native species ( Powell et al. , 2011 ) and whether herbivores and predators prefer to consume native or introduced species ( Morrison and Hay, 2011 ; Jaworski et al. , 2013 ). Introduced species can also affect the diet quality of their consumers, but this effect will depend on how the ratio of nutrients and secondary compounds differs between native and introduced prey ( Maerz et al. , 2010 ).

Introduced species can have diverse effects on species interactions. A famous example of a successful invasive species is the Eurasian zebra mussel ( Dreissena polymorpha ). Zebra mussels modify the concentration of nutrients and the community of algae in whole ecosystems ( Caraco et al. , 1997 ) thus affecting the diet of native species through changing the availability of alternative food ( Gonzalez and Downing, 1999 ), and through consumption as a direct food source that for some species provides less energy than normal prey ( Watzin et al. , 2008 ). In Australia, toxic cane toads ( Bufo marinus ) were introduced to deal with plant pests, but their presence has had many unintended consequences. For example, northern trout gudgeon ( Mogurnda mogurnda ) exposed to cane toad tadpoles showed reduced rate of consumption of native tadpoles ( Nelson et al. , 2010 ) and adult cane toads reduce the activity of native frogs during foraging ( Mayer et al. , 2015 ). Introduced benthivorous fish, such as goldfish ( Carassius auratus ) and common carp ( Cyprinus carpio ), increase water turbidity through the mechanical actions of foraging, thus affecting the foraging success of other aquatic species (see ‘Pollution’ section) ( Richardson et al. , 1995 ; Zembrano et al. , 2001 ). However, there has been a lack of study focused on the nutritional effects on native animals beyond simple consumption, and none linking these effects to fitness.

Anthropogenic disturbances

Human disturbance can modify feeding strategies through increased nocturnal illumination and acoustic disturbances. Natural lighting cycles affect foraging in a wide variety of species (reviewed in Navara and Nelson, 2007 ) and so it should be no surprise that artificial lighting changes these behaviours, especially as it can exceed the intensity of any natural lunar phase ( Cinzano et al. , 2001 ). Both prey and predators are affected by artificial light. Insects are readily attracted to nocturnal lights, and this is changing not only the abundance but also the species composition of this prey base ( Davies et al. , 2012 ). Some prey reduce foraging under lights ( Kotler, 1984 ; Contor and Griffith, 1995 ; Brown et al. , 1998 ; Baker and Richardson, 2006 ) while others increase it ( Biebouw and Blumstein, 2003 ), changes often linked to increased predation risk under illumination ( Rich and Longcore, 2013 ). Similarly, night lighting may impair the vision of some predators ( Buchanan, 1993 ) while others are more active and use the increased visibility ( Yurk and Trites, 2000 ; Rich and Longcore, 2013 ) which may change their distribution in the environment ( Montevecchi, 2006 ). However, when the light itself mimics a foraging cue, individuals may not possess the flexibility to change their behaviour ( Schlaepfer et al. , 2002 ). For example, juveniles of many seabird species are drawn to lights, possibly because they resemble their bioluminescent prey ( Montevecchi, 2006 )—a clearly maladaptive response. In general, the severity of the effects of artificial illumination will depend on the trade-off between predation, foraging and competition, whether the species are naturally nocturnal or diurnal, and whether these new cues trigger previously adaptive responses.

Acoustic disturbance has increased drastically over the past century, affecting communication in urban populations ( Birnie-Gauvin et al. , 2016 ). Anthropogenic noise can have similar effects to artificial lighting in that it may hinder an individual’s ability to identify prey and/or predators, or lead to chronic stress, which may in turn lead to decreased foraging efficiency and lower reproductive success ( National Research Council, 2005 ; Schroeder et al. , 2012 : Meillere et al. , 2015 : Shannon et al. , 2015 ). This form of feeding disturbance is especially detrimental to animals that rely on acoustic cues to locate food items. For example, sonar-using greater mouse-eared bats ( Myotis myotis ) spend less time foraging when exposed to traffic noise ( Jones, 2008 ). However, some species have the ability to cope with noise pollution. For example, the foraging behaviour (i.e. diving frequency) of mysticete whales ( Balaenoptera physalus and B. musculus ) was largely unaffected by low frequency sounds which are typical of cargo ships and oil development infrastructure ( Croll et al. , 2001 ). In fact, whale behaviour appeared to be more closely related to prey abundance than to acoustic disturbance ( Croll et al. , 2001 ). When noise causes individuals to shift attention, foraging often suffers. For example, noise led chaffinches ( Fringilla coelebs ) to increase vigilance (scanning for predators) and decrease food intake ( Quinn et al. , 2006 ), and caused decreased foraging efficiency in three-spined stickleback ( Gasterosteus aculeatus ) ( Purser and Radford, 2011 ). However, if specialists are also more efficient at foraging, additional time dedicated to detecting predators may be more costly to generalist species ( Chan and Blumstein, 2011 ). The contrasting results from studies that investigate the effects of noise on feeding behaviour suggests that depending on the feeding nature of organisms, they may be affected differently and to varying degree. Many reviews have suggested that foraging is affected by noise ( Kight and Swaddle, 2011 ; Francis and Barber, 2013 ), but few studies have made direct links to nutrition.

Another important form of disturbance is the very presence of humans, which is presumably the most direct form of anthropogenic disturbance for wild organisms and generally results in an energy cost ( Houston et al. , 2012 ). This may come in the form of hunting, horseback riding, biking, hiking, camping, swimming, fishing, skiing, photographers, or observers ( Cole and Knight, 1991 ; Boyle and Samson, 1985 ; Knight and Gutzwiller, 1995 ; Hammitt et al. , 2015 ). The effects of such recreational activities on nutrition have seldom been investigated, but behaviour can be highly affected by human presence. For example, the presence of observers near the territories of European oystercatchers ( Haematopus ostralegus ) led to less time spent foraging and reduced food intake for the parents, and decreased the proportion of food allocated to the chicks ( Verhulst et al. , 2001 ). In marsh harriers ( Circus aeruginosus ), disturbance by fisherman, passers-by, dogs, and vehicles also resulted in lower food provisioning and higher nutritional stress in chicks ( Fernández and Azkona, 1993 ). However, brown bears ( Ursus arctos ) showed minimal effects of human presence as they altered their behaviour to maintain food intake and body condition ( Rode et al. , 2006c , 2007 ). Yet the same species of bear decreased their foraging activity and fed on berries of poorer quality when hunting risk was high ( Hertel et al. , 2016 ). When endangered Amur tigers ( Panthera tigris altaica ) were disturbed, they often abandoned kills, spent less time at the kill when they stayed and consumed less meat ( Kerley et al. , 2002 ). Elk ( Cervus elaphus ) fled in response to skiers, often moving upslope to areas with poorer quality vegetation ( Frances Cassirer et al. , 1992 ). Bald eagles ( Haliaetus leucocephalus ) rarely fed at salmon carcasses when disturbed while glaucous-winged gulls ( Larus glaucescens ) fed more, indicating gulls were more wary of the dominant heterospecific than of people ( Skagen et al. , 1991 ). Disturbance also led to changes in temporal feeding activity of bald eagles, crows and ravens ( Knight et al. , 1991 ). Responses to people may also differ between the sexes. Female brown bears with young prioritize avoidance of male bears over avoidance of humans, while male site use was linked to prey availability ( Rode et al. , 2006b ). The presence of people often results in behavioural modifications in feeding activity or location that may result in poorer body condition and lower reproductive success in animals that are sensitive to this presence.

Human-provisioned food sources

In urban areas, humans often provide a source of food for many wild animals, both inadvertently (e.g. through garbage) or on purpose (e.g. bird seeds in the backyard; Murray et al. , 2016 ). In most industrialized countries, these foods have a high level of predictability both spatially and temporally ( Chamberlain et al. , 2005 ; Oro et al. , 2013 ). Such food provisioning may affect food webs and communities, changing competitive and predator-prey interactions and nutrient transfer processes (reviewed in Oro et al. , 2013 ), primarily due to ease of access in comparison to natural food sources ( Bartumeus et al. , 2010 ) which reduces time spent foraging ( Orams, 2002 ).

Unintentional food provisioning usually involves refuse sites (dumps, middens, harvest discards, etc.). Many cosmopolitan opportunistic species such as gulls, rats and foxes have benefited greatly from these food subsidies, showing improved body condition and reduced susceptibility to pathogens (reviewed in Carey et al. , 2012 ; Oro et al. , 2013 ). Vervet monkeys ( Chlorocebus pygerythrus ) spent less time foraging and had higher reproduction but also increased aggression while feeding on garbage ( Lee et al. , 1986 ), while olive baboons ( Papio anubis ) with access to garbage also spent less time foraging and had higher body condition and lower levels of parasite infection than naturally-foraging groups ( Eley et al. , 1989 ). In other cases, food provisioning is not beneficial. For example, fisheries bycatch provides seabirds with access to prey that have a lower energetic content than their normal pelagic prey ( Grémillet et al. , 2008 ). During the non-breeding season seabirds can use bycatch and still meet their own nutritional needs, but when breeding commences females need to consume pelagic prey due to the energetic requirements of egg formation ( Louzao et al. , 2006 ; Navarro et al. , 2009 ) and chicks fed on bycatch have lower growth rates and survival ( Grémillet et al. , 2008 ). Unintentional provisioning may also include cultivated fruit trees, compost and dropped bird seed, all of which are highly attractive to urban wildlife (reviewed in Murray et al. , 2015 ). These low-protein but easily accessible foods may either cause poor health or be used by animals already in poor health, increasing the likelihood of human-wildlife conflicts ( Murray et al. , 2015 ). Human food sources can also increase interactions among wildlife. For example, Steller’s jay ( Cyanocitta stelleri ) utilizes anthropogenic food at campsites, and though the effects on the jay’s nutrition are not known, access to this food source may result in increased predation on the endangered marbled murrelet ( Brachyramphus marmoratus ) ( Goldenberg, 2013 ). When food left at campsites attracts flocks of carnivores and omnivores, small-bodied herbivores may be excluded from the area ( Densmore and French, 2005 ). Thus the extent, timing and quality of human-provisioned resources will determine the effects of using this alternative prey.

Wildlife tourism is an important source of income for many countries ( Braithwaite, 2001 ) and can be a motivation for intentional feeding (reviewed in Orams, 2002 ). However, this form of interaction can be highly detrimental to wildlife ( Murray et al. , 2016 ). For example, both stingrays ( Semeniuk et al. , 2007 ) and iguanas ( Knapp et al. , 2013 ) fed by tourists show poorer indicators of adequate nutrition than those eating natural food. Moreover, interactions at food sources can lead to increased risk of injury for animals, as is observed in chacma baboons ( Papio ursinus ) where these injuries also hindered their foraging efficiency ( Beamish, 2009 ). The feeding of wildlife can also cause an aggregation of individuals at feeding sites ( Newsome and Rodger, 2008 ), potentially reducing food intake per individual through competition ( Raman, 1996 ). Even backyard feeding of birds can affect subsequent reproduction ( Ruffino et al. , 2014 ) as provisioned food is often calorie-rich but nutrient-poor ( Plummer et al. , 2013 ). Provisioned food may even have unpredictable effects on nutrition when it interacts with other components of the diet. For example, white-tailed deer supplemented with hay and corn consumed less digestible energy in areas where they also consumed lichen which reduces feed retention times ( Page and Underwood, 2006 ). Humans enjoy being in close contact with animals, but when this involves feeding wildlife, the health of the wildlife is often of secondary importance. Some of these negative effects of ecotourism may be overcome by focusing on animals that possess sufficient behavioural plasticity to eliminate the effects of humans on an individual’s spatiotemporal resource use (e.g. brown bears: Rode et al. , 2007 ). Additionally, when ecotourism is designed to reduce negative impacts on wildlife and is also used as a source of education about their proper feeding, everyone benefits ( Ballantyne et al. , 2009 ).

The degree to which food supplementation has long-term effects on populations remains largely unknown. There are few long-term studies of the effects of supplemented feeding on nutrition in wildlife ( Orams, 2002 ). The evolutionary consequences have so far been virtually ignored, even though it has been hypothesized that in cases where the more aggressive individuals obtain the most food and thus leave more offspring, supplemental feeding can be a source of selection and change the phenotypes in a population ( Moribe, 2000 ). Nonetheless, when the provisioning of additional food items has benefits such as higher survival ( Orams, 2002 ), these short-term gains may be important enough to offset the possible effects on population dynamics. This concept has recently been extended to include the use of carcass provisioning as a conservation strategy to enhance survival for scavenger species ( Fielding et al. , 2014 ).

Nutrition and in situ conservation

In situ conservation (e.g. habitat restoration, supplemental feeding) aims to manage and protect species in natural habitats ( Possiel et al. , 1995 ). In the context of nutrition, this requires balancing foraging behaviours and food availability (which are affected by all six categories of human-caused modifications; Fig. Fig.1) 1 ) with nutritional physiology. This may involve studying foraging ecology, measuring the nutritional composition of foods, providing non-naturally occurring food, and investigating these impacts on digestive physiology to ensure sufficient energy and nutrient intake ( Hobbs and Harris, 2001 ; Hobbs et al. , 2009 ). For example, it was necessary to supplement the endangered hihi ( Notiomnystis cincta ) with carbohydrates to increase reproductive success ( Castro et al. , 2003 ), and knowledge of foraging behaviours and nutrient requirements of the vulnerable Tonkean macaques ( Macaca tonkeana ) can help reduce damaging crop raiding behaviours ( Riley et al. , 2013 ). Detailed studies of wild populations are often necessary to know what forage species are preferred (used versus available: Johnson, 1980 ). They may have to be long-term to account for seasonal (e.g. Karachle and Stergiou, 2008 ; Adeola et al. , 2014 ) or inter-annual (Esque, 1994) variation in prey consumption, and they may have to measure many individuals and multiple populations as the level of individual dietary specialization can vary with resource availability ( Bolnick et al. , 2002 ), individual mechanisms to deal with changing food availability vary with sex and condition ( Martin, 1987 ), and food preference can be under genetic control and locally adapted ( Sotka, 2003 ). Actual measures of nutrition are often invasive, and non-invasive alternatives are still lacking validation for many wild species ( Murray et al. , 2016 ). Thus, measuring food intake and diet composition for wild animals is a difficult task, but there are many techniques that make addressing these questions possible ( Cooke et al. , 2004 ; Robbins et al. , 2004 ; Servello et al. , 2005 ; Andrews et al. , 2008 ; Rothman et al. , 2012 ; Machovsky-Capuska et al. , 2016 ; see Table Table1 1 ).

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Anthropogenic effects on components of animal nutrition. Human presence has altered the environment. Here, we identify how these human modifications (climate change, pollution, invasive species, habitat alterations, disturbance and human-provisioned food) affect aspects of nutrition through effects on foraging behaviour, food availability and digestive physiology (solid black arrows represent links already established in the literature; dotted arrows represent hypothetical links). Depending on how these three aspects of nutrition are altered, locomotion, activity and cognition may change, affecting reproduction, growth and survival. These may in turn affect demography and population dynamics, which may affect evolutionary processes.

An example involves the desert tortoise ( Gopherus agassizii ), which was put under the Endangered Species Act in 1989 due to huge population declines ( U.S. Fish and Wildlife Service, 1994 ). The threats to the desert tortoise were considered to be mostly physiological, of which many could be attributed (directly or indirectly) to nutrition ( Tracy et al. , 2006 ). The presence of domestic grazers, the occurrence of fires and the invasion of weedy plants—all of which are largely caused by humans—contributed to their nutritional deficiencies by reducing plant diversity ( U.S. Fish and Wildlife Service, 1994 ). Each tortoise obtained approximately 90% of their diet from 5 species of plants, but the specific species eaten differed across individuals resulting in more than 30 species of plants consumed at the population level ( Tracy et al. , 2006 ). The mechanisms causing this were complex, and mainly involved choice of plants with high digestible energy (used versus available), and individual encounters with specific plant species early in the season (switching foods incurs a cost when gut microbes are specific to the plants consumed), suggesting that a variety of species should be made available to tortoises in the context of in situ conservation to fulfil individual nutrition needs ( Tracy et al. , 2006 ). Inadequate dietary intake caused by low species diversity can induce stress and lead to compromised immunity and increased susceptibility to disease, which in the case of the desert tortoise has had severe impacts on population densities, providing evidence for the importance of nutrition in conservation biology; Box 2 .

Nutrition in in situ conservation: the tiger

Tigers ( Panthera tigris ) are a globally endangered species that have suffered huge population losses as a result of human presence ( Chundawat et al. , 2012 ). However, in Nepal, conservation efforts have resulted in the tiger population increasing by 63% in recent years ( Government of Nepal, 2013 ; Aryal et al. , 2016 ). Yet the prey biomass within currently protected areas may be insufficient to provide food for the projected increased tiger population ( Aryal et al. , 2016 ). It has been suggested that programs should be implemented to increase prey populations in situ to continue conservation efforts and restore tiger populations. ( Image by Martin Harvey, World Wildlife Fund )

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Nutrition and ex situ conservation

While in situ conservation approaches have been considered a legal and institutional priority by the Convention on Biological Diversity ( www.cbd.int ), it is increasingly apparent that the importance of ex situ conservation is growing, as extinction rates continue to rise and are exacerbated by climate change ( Pritchard et al. , 2012 ). Ex situ conservation aims to conserve species in captivity and relies on facilities that hold plants and animals such as zoos, aquaria and botanical gardens, and even private breeders. The knowledge gained from these facilities can also be used to support conservation efforts. When inadequate diets in captivity lead to an individual’s death or failure to reproduce, there is increasing pressure to collect more individuals from the wild. For example, many species of parrots and iguanas are popular pets. However, these pets are often fed nutritionally inadequate diets, leading to death via malnutrition or increased susceptibility to disease and more animals collected illegally from the wild ( Dohoghue, 1994 ; Schlaepfer et al. , 2005 ; Weston and Memon, 2009 ). If these owners were made aware of proper nutrition for these birds, harvest of wild populations would decrease.

The importance of meeting nutritional requirements to conserve and manage endangered and at-risk species should not be understated ( Oftedal and Allen, 1996 ; see Box 3 ). Food quantity continues to be the primary focus in zoological parks, despite the recognition that food quality plays a huge role in maintaining animal health and reproductive potential (see Box 1 ). For example, in captive ruminants, browsers have a higher nutrition-related mortality than grazers because browsers are fed a type of roughage that is not very similar to their natural foods, resulting in too little roughage ingested compared to seeds/grains and causing digestion issues ( Müller et al. , 2010 ). Providing foods and food combinations of adequate quality is a more difficult task than food quantity, the latter which can be addressed by simply providing more known suitable foods. In a captive breeding project, green iguana ( Iguana iguana ) hatchlings and juveniles grew more rapidly when fed diets high in protein than when fed lower protein diets ( Allen et al. , 1989 ). High growth rates are considered important for young iguanas as predation risks are high and thus individual size determined the age at which these iguanas could be released into the wild ( Oftedal and Allen, 1996 ). In captive mule deer ( Odocoileus hemionus ), diets supplemented with feed concentrates, oats and barley resulted in increased body mass and antler size, as well as earlier breeding and a decrease in fawn mortality ( Robinette et al. , 1973 ). Following this increased food intake, the productivity of this captive herd surpassed that of wild populations ( Robinette et al. , 1973 ).

The importance of nutrition for animals

Adequate dietary intake (both calories and nutrients) is essential to the growth and reproductive success of vertebrates. In fact, the physiological component of reproduction and sexual behaviour is extremely sensitive to the intake of metabolic fuels ( Wade et al. , 1996 ; Allen and Ullrey, 2004 ; Parker et al. , 2009 ). Organisms will forego reproduction if they do not have the energetic resources to invest in gonadal development or reproductive activities. However, calories alone are insufficient for the maintenance of health, growth (somatic or reproductive) and other routine functions such as cognition. For example, mammals require proper nutrients for successful parturition and the production of colostrum and milk, while birds require calcium to make eggshells ( Robbins, 1993 ). Proteins and amino acids are crucial for proper organ development ( Welham-Simon et al. , 2002 ) and egg production ( Ramsay and Houston, 1998 ). Fatty acids are essential for brain development and neurogenesis ( Schiefermeier and Yavin, 2002 ), as well as for components of spermatozoa ( Surai et al. , 2000 ). Minerals and vitamins are also an important aspect of nutrient intake. For example, a lack of dietary selenium can impair reproductive performance ( Cantor and Scott, 1974 ), while zinc deficiency is linked to testicular underdevelopment ( Martin et al. , 1994 ). Vitamin A is a crucial micronutrient for proper eye development, vision and cellular differentiation ( National Research Council, 1995 ), and vitamins E and C are important for oxidative homeostasis ( Castellini et al. , 2000 ). In addition, it has long been recognized that diet plays an essential role in maintaining immunity against diseases ( Lall and Olivier, 1993 ). For example, megadoses of vitamin C have been shown to improve antibody response and survival following infection in the channel catfish ( Ictalurus punctatus ; Li and Lovell, 1985 ; Liu et al. , 1989 ). Diet also affects cognitive processes: lipid-poor diets decrease the ability of kittiwakes ( Rissa brevirostris ) to learn the location of food ( Kitaysky et al. , 2006 ). Thus, macronutrients and micronutrients play essential roles in the proper development of animals, from embryo to reproductive adult.

Nutrition in ex situ conservation: the kakapo

The kakapo ( Strogops habroptilus ) is a large, flightless parrot endemic to New Zealand. It was put on the critically endangered list in 1989, largely due to catastrophic population declines caused by introduced mammalian predators ( Williams, 1956 : Powlesland and Lloyd, 1994 ). The kakapo only breed in years during which podocarp trees produce abundant fruit, which occurs every 2–6 years ( Powlesland and Lloyd, 1994 ; Cockrem, 2006 ). When supplemented with specially formulated pellets that contained protein, micronutrients, mineral supplements and amino acids, females produced larger clutches but did not change nesting frequency, suggesting that podocarp fruiting is the cue for breeding while the number of eggs is limited by nutritional quality rather than energetic content ( Houston et al. , 2007 ). Hand-rearing of chicks using artificial foods now plays a critical role in the management of this critically endangered species ( Waite et al. , 2013 ). ( Image by Milena Scott )

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Conclusion and research needs

Nutritional ecology has been most extensively studied in terrestrial herbivorous mammals ( Choat and Clements, 1998 ) and while progress has been made in other taxa, including marine herbivorous fishes ( Clements et al. , 2009 ) and insects ( Slansky, 1982 ; Simpson et al. , 2015 ), other groups such as predators are still lacking such information. Despite many papers citing nutritional deficiencies as a possible consequence of human interactions, few studies have actually investigated the proposed links ( Jones and Reynolds, 2008 ), but nutritional stress is now being included in population modelling frameworks ( National Academy of Sciences, Engineering and Medicine, 2016 ). However, we now have the tools to measure very detailed aspects of physiology related to nutrition (e.g. microbiomes: Lyons et al. , 2016 ; secondary compounds: Sotka and Whalen, 2008 ). Further work is clearly needed to identify the most pressing aspects of human-caused changes to food quality and quantity, such as: how animals choose which forage items to consume (e.g. can individuals learn about changes in toxicity or nutrient composition? Are genetic food preferences evolving in response to anthropogenic effects?); the interaction between energy availability and optimal digestion ( Tracy et al. , 2006 ); the ways in which animals may plastically respond and/or evolve to cope with anthropogenic impacts ( Crispo et al. , 2010 ; Sih et al. , 2011 ); how to design conservation solutions while recognizing that the choices animals make are constrained by evolutionary history ( Schlaepfer et al. , 2002 ); and the frequency of synergistic effects across different anthropogenic impacts ( Opdam and Wascher, 2004 ). A common pitfall of nutritional ecology and physiology is that hypotheses are often based on energetic intake and density (i.e. calories) rather than macronutrients and micronutrients, the latter of which we still know little about. We emphasize the importance of considering all aspects of nutrition (nutrient intake, foraging behaviour and digestive physiology, Fig. Fig.1) 1 ) when developing hypotheses about the effects of human activities on wildlife.

It is apparent that humans have altered many aspects of vertebrate nutrition. All anthropogenic impacts we focused on had documented negative effects on foraging behaviour and the availability of food, though most studies focused on quantity rather than quality of food. Very few investigated whether those changes affected digestion efficiency and energy acquisition, even though some forms of impact, such as provisioned food, logically seem like they should have large effects. In today’s changing world, animals eat food items they did not previously eat; they must invest more energy in foraging efforts than they previously had to (with the exception of wildlife that has access to human-provisioned food sources); and they now ingest more pollutants than they used to. All of these changes to nutritional intake can influence the reproductive capacity, growth and overall survival of wild animals. Our current understanding of the long-term effects of such modifications are poorly understood, and we urge for more research to consider the impacts that changing nutrition may have on animals in the long term as part of a broader conservation physiology approach ( Cooke et al. , 2013 ). More specifically, the links between nutrient quality/quantity and various aspects of physiology (i.e. reproductive functions, immunity, stress response, etc.) and their population-level consequences should be investigated ( National Academy of Sciences, Engineering and Medicine, 2016 ). By understanding the mechanisms by which nutrition is affected by anthropogenic factors, we may have a greater opportunity to minimize their threats.

This work was supported by the Natural Sciences and Engineering Research Council of Canada [315 774-166] and the Canada Research Chairs program. D.R. is supported by Australian Research Council Linkage Grant [Project ID: LP 140100235].

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12.4 Annotated Student Sample: "Healthy Diets from Sustainable Sources Can Save the Earth" by Lily Tran

Learning outcomes.

By the end of this section, you will be able to:

Analyze how writers use evidence in research writing.
Analyze the ways a writer incorporates sources into research writing, while retaining their own voice.
Explain the use of headings as organizational tools in research writing.
Analyze how writers use evidence to address counterarguments when writing a research essay.

Introduction

In this argumentative research essay for a first-year composition class, student Lily Tran creates a solid, focused argument and supports it with researched evidence. Throughout the essay, she uses this evidence to support cause-and-effect and problem-solution reasoning, make strong appeals, and develop her ethos on the topic.

Living by Their Own Words

Food as change.

public domain text For the human race to have a sustainable future, massive changes in the way food is produced, processed, and distributed are necessary on a global scale. end public domain text

annotated text Purpose. Lily Tran refers to what she sees as the general purpose for writing this paper: the problem of current global practices in food production, processing, and distribution. By presenting the “problem,” she immediately prepares readers for her proposed solution. end annotated text

public domain text The required changes will affect nearly all aspects of life, including not only world hunger but also health and welfare, land use and habitats, water quality and availability, energy use and production, greenhouse gas emissions and climate change, economics, and even cultural and social values. These changes may not be popular, but they are imperative. The human race must turn to sustainable food systems that provide healthy diets with minimal environmental impact—and starting now. end public domain text

annotated text Thesis. Leading up to this clear, declarative thesis statement are key points on which Tran will expand later. In doing this, she presents some foundational evidence that connects the problem to the proposed solution. end annotated text

THE COMING FOOD CRISIS

public domain text The world population has been rising exponentially in modern history. From 1 billion in 1804, it doubled to approximately 2 billion by 1927, then doubled again to approximately 4 billion in 1974. By 2019, it had nearly doubled again, rising to 7.7 billion (“World Population by Year”). It has been projected to reach nearly 10 billion by 2050 (Berners-Lee et al.). At the same time, the average life span also has been increasing. These situations have led to severe stress on the environment, particularly in the demands for food. It has been estimated, for example, that by 2050, milk production will increase 58 percent and meat production 73 percent (Chai et al.). end public domain text

annotated text Evidence. In this first supporting paragraph, Tran uses numerical evidence from several sources. This numerical data as evidence helps establish the projection of population growth. By beginning with such evidence, Tran underscores the severity of the situation. end annotated text

public domain text Theoretically, the planet can produce enough food for everyone, but human activities have endangered this capability through unsustainable practices. Currently, agriculture produces 10–23 percent of global greenhouse gas emissions. Greenhouse gases—the most common being carbon dioxide, methane, nitrous oxide, and water vapor— trap heat in the atmosphere, reradiate it, and send it back to Earth again. Heat trapped in the atmosphere is a problem because it causes unnatural global warming as well as air pollution, extreme weather conditions, and respiratory diseases. end public domain text

annotated text Audience. With her audience in mind, Tran briefly explains the problem of greenhouse gases and global warming. end annotated text

public domain text It has been estimated that global greenhouse gas emissions will increase by as much as 150 percent by 2030 (Chai et al.). Transportation also has a negative effect on the environment when foods are shipped around the world. As Joseph Poore of the University of Oxford commented, “It’s essential to be mindful about everything we consume: air-transported fruit and veg can create more greenhouse gas emissions per kilogram than poultry meat, for example” (qtd. in Gray). end public domain text

annotated text Transition. By beginning this paragraph with her own transition of ideas, Tran establishes control over the organization and development of ideas. Thus, she retains her sources as supports and does not allow them to dominate her essay. end annotated text

public domain text Current practices have affected the nutritional value of foods. Concentrated animal-feeding operations, intended to increase production, have had the side effect of decreasing nutritional content in animal protein and increasing saturated fat. One study found that an intensively raised chicken in 2017 contained only one-sixth of the amount of omega-3 fatty acid, an essential nutrient, that was in a chicken in 1970. Today the majority of calories in chicken come from fat rather than protein (World Wildlife Fund). end public domain text

annotated text Example. By focusing on an example (chicken), Tran uses specific research data to develop the nuance of the argument. end annotated text

public domain text Current policies such as government subsidies that divert food to biofuels are counterproductive to the goal of achieving adequate global nutrition. Some trade policies allow “dumping” of below-cost, subsidized foods on developing countries that should instead be enabled to protect their farmers and meet their own nutritional needs (Sierra Club). Too often, agriculture’s objectives are geared toward maximizing quantities produced per acre rather than optimizing output of critical nutritional needs and protection of the environment. end public domain text

AREAS OF CONCERN

Hunger and nutrition.

annotated text Headings and Subheadings. Throughout the essay, Tran has created headings and subheadings to help organize her argument and clarify it for readers. end annotated text

public domain text More than 820 million people around the world do not have enough to eat. At the same time, about a third of all grains and almost two-thirds of all soybeans, maize, and barley crops are fed to animals (Barnard). According to the World Health Organization, 462 million adults are underweight, 47 million children under 5 years of age are underweight for their height, 14.3 million are severely underweight for their height, and 144 million are stunted (“Malnutrition”). About 45 percent of mortality among children under 5 is linked to undernutrition. These deaths occur mainly in low- and middle-income countries where, in stark contrast, the rate of childhood obesity is rising. Globally, 1.9 billion adults and 38.3 million children are overweight or obese (“Obesity”). Undernutrition and obesity can be found in the same household, largely a result of eating energy-dense foods that are high in fat and sugars. The global impact of malnutrition, which includes both undernutrition and obesity, has lasting developmental, economic, social, and medical consequences. end public domain text

public domain text In 2019, Berners-Lee et al. published the results of their quantitative analysis of global and regional food supply. They determined that significant changes are needed on four fronts: end public domain text

Food production must be sufficient, in quantity and quality, to feed the global population without unacceptable environmental impacts. Food distribution must be sufficiently efficient so that a diverse range of foods containing adequate nutrition is available to all, again without unacceptable environmental impacts. Socio-economic conditions must be sufficiently equitable so that all consumers can access the quantity and range of foods needed for a healthy diet. Consumers need to be able to make informed and rational choices so that they consume a healthy and environmentally sustainable diet (10).

annotated text Block Quote. The writer has chosen to present important evidence as a direct quotation, using the correct format for direct quotations longer than four lines. See Section Editing Focus: Integrating Sources and Quotations for more information about block quotes. end annotated text

public domain text Among their findings, they singled out, in particular, the practice of using human-edible crops to produce meat, dairy, and fish for the human table. Currently 34 percent of human-edible crops are fed to animals, a practice that reduces calorie and protein supplies. They state in their report, “If society continues on a ‘business-as-usual’ dietary trajectory, a 119% increase in edible crops grown will be required by 2050” (1). Future food production and distribution must be transformed into systems that are nutritionally adequate, environmentally sound, and economically affordable. end public domain text

Land and Water Use

public domain text Agriculture occupies 40 percent of Earth’s ice-free land mass (Barnard). While the net area used for producing food has been fairly constant since the mid-20th century, the locations have shifted significantly. Temperate regions of North America, Europe, and Russia have lost agricultural land to other uses, while in the tropics, agricultural land has expanded, mainly as a result of clearing forests and burning biomass (Willett et al.). Seventy percent of the rainforest that has been cut down is being used to graze livestock (Münter). Agricultural use of water is of critical concern both quantitatively and qualitatively. Agriculture accounts for about 70 percent of freshwater use, making it “the world’s largest water-consuming sector” (Barnard). Meat, dairy, and egg production causes water pollution, as liquid wastes flow into rivers and to the ocean (World Wildlife Fund and Knorr Foods). According to the Hertwich et al., “the impacts related to these activities are unlikely to be reduced, but rather enhanced, in a business-as-usual scenario for the future” (13). end public domain text

annotated text Statistical Data. To develop her points related to land and water use, Tran presents specific statistical data throughout this section. Notice that she has chosen only the needed words of these key points to ensure that she controls the development of the supporting point and does not overuse borrowed source material. end annotated text

annotated text Defining Terms. Aware of her audience, Tran defines monocropping , a term that may be unfamiliar. end annotated text

public domain text Earth’s resources and ability to absorb pollution are limited, and many current agricultural practices undermine these capacities. Among these unsustainable practices are monocropping [growing a single crop year after year on the same land], concentrated animal-feeding operations, and overdependence on manufactured pesticides and fertilizers (Hamilton). Such practices deplete the soil, dramatically increase energy use, reduce pollinator populations, and lead to the collapse of resource supplies. One study found that producing one gram of beef for human consumption requires 42 times more land, 2 times more water, and 4 times more nitrogen than staple crops. It also creates 3 times more greenhouse gas emissions (Chai et al.). The EAT– Lancet Commission calls for “halting expansion of new agricultural land at the expense of natural ecosystems . . . strict protections on intact ecosystems, suspending concessions for logging in protected areas, or conversion of remaining intact ecosystems, particularly peatlands and forest areas” (Willett et al. 481). The Commission also calls for land-use zoning, regulations prohibiting land clearing, and incentives for protecting natural areas, including forests. end public domain text

annotated text Synthesis. The paragraphs above and below this comment show how Tran has synthesized content from several sources to help establish and reinforce key supports of her essay . end annotated text

Greenhouse Gas and Climate Change

public domain text Climate change is heavily affected by two factors: greenhouse gas emissions and carbon sequestration. In nature, the two remain in balance; for example, most animals exhale carbon dioxide, and most plants capture carbon dioxide. Carbon is also captured, or sequestered, by soil and water, especially oceans, in what are called “sinks.” Human activities have skewed this balance over the past two centuries. The shift in land use, which exploits land, water, and fossil energy, has caused increased greenhouse-gas emissions, which in turn accelerate climate change. end public domain text

public domain text Global food systems are threatened by climate change because farmers depend on relatively stable climate systems to plan for production and harvest. Yet food production is responsible for up to 30 percent of greenhouse gas emissions (Barnard). While soil can be a highly effective means of carbon sequestration, agricultural soils have lost much of their effectiveness from overgrazing, erosion, overuse of chemical fertilizer, and excess tilling. Hamilton reports that the world’s cultivated and grazed soils have lost 50 to 70 percent of their ability to accumulate and store carbon. As a result, “billions of tons of carbon have been released into the atmosphere.” end public domain text

annotated text Direct Quotation and Paraphrase. While Tran has paraphrased some content of this source borrowing, because of the specificity and impact of the number— “billions of tons of carbon”—she has chosen to use the author’s original words. As she has done elsewhere in the essay, she has indicated these as directly borrowed words by placing them within quotation marks. See Section 12.5 for more about paraphrasing. end annotated text

public domain text While carbon sequestration has been falling, greenhouse gas emissions have been increasing as a result of the production, transport, processing, storage, waste disposal, and other life stages of food production. Agriculture alone is responsible for fully 10 to 12 percent of global emissions, and that figure is estimated to rise by up to 150 percent of current levels by 2030 (Chai et al.). Münter reports that “more greenhouse gas emissions are produced by growing livestock for meat than all the planes, trains, ships, cars, trucks, and all forms of fossil fuel-based transportation combined” (5). Additional greenhouse gases, methane and nitrous oxide, are produced by the decomposition of organic wastes. Methane has 25 times and nitrous oxide has nearly 300 times the global warming potential of carbon dioxide (Curnow). Agricultural and food production systems must be reformed to shift agriculture from greenhouse gas source to sink. end public domain text

Social and Cultural Values

public domain text As the Sierra Club has pointed out, agriculture is inherently cultural: all systems of food production have “the capacity to generate . . . economic benefits and ecological capital” as well as “a sense of meaning and connection to natural resources.” Yet this connection is more evident in some cultures and less so in others. Wealthy countries built on a consumer culture emphasize excess consumption. One result of this attitude is that in 2014, Americans discarded the equivalent of $165 billion worth of food. Much of this waste ended up rotting in landfills, comprised the single largest component of U.S. municipal solid waste, and contributed a substantial portion of U.S. methane emissions (Sierra Club). In low- and middle-income countries, food waste tends to occur in early production stages because of poor scheduling of harvests, improper handling of produce, or lack of market access (Willett et al.). The recent “America First” philosophy has encouraged prioritizing the economic welfare of one nation to the detriment of global welfare and sustainability. end public domain text

annotated text Synthesis and Response to Claims. Here, as in subsequent sections, while still relying heavily on facts and content from borrowed sources, Tran provides her synthesized understanding of the information by responding to key points. end annotated text

public domain text In response to claims that a vegetarian diet is a necessary component of sustainable food production and consumption, Lusk and Norwood determined the importance of meat in a consumer’s diet. Their study indicated that meat is the most valuable food category to consumers, and “humans derive great pleasure from consuming beef, pork, and poultry” (120). Currently only 4 percent of Americans are vegetarians, and it would be difficult to convince consumers to change their eating habits. Purdy adds “there’s the issue of philosophy. A lot of vegans aren’t in the business of avoiding animal products for the sake of land sustainability. Many would prefer to just leave animal husbandry out of food altogether.” end public domain text

public domain text At the same time, consumers expect ready availability of the foods they desire, regardless of health implications or sustainability of sources. Unhealthy and unsustainable foods are heavily marketed. Out-of-season produce is imported year-round, increasing carbon emissions from air transportation. Highly processed and packaged convenience foods are nutritionally inferior and waste both energy and packaging materials. Serving sizes are larger than necessary, contributing to overconsumption and obesity. Snack food vending machines are ubiquitous in schools and public buildings. What is needed is a widespread attitude shift toward reducing waste, choosing local fruits and vegetables that are in season, and paying attention to how foods are grown and transported. end public domain text

annotated text Thesis Restated. Restating her thesis, Tran ends this section by advocating for a change in attitude to bring about sustainability. end annotated text

DISSENTING OPINIONS

annotated text Counterclaims . Tran uses equally strong research to present the counterargument. Presenting both sides by addressing objections is important in constructing a clear, well-reasoned argument. Writers should use as much rigor in finding research-based evidence to counter the opposition as they do to develop their argument. end annotated text

public domain text Transformation of the food production system faces resistance for a number of reasons, most of which dispute the need for plant-based diets. Historically, meat has been considered integral to athletes’ diets and thus has caused many consumers to believe meat is necessary for a healthy diet. Lynch et al. examined the impact of plant-based diets on human physical health, environmental sustainability, and exercise performance capacity. The results show “it is unlikely that plant-based diets provide advantages, but do not suffer from disadvantages, compared to omnivorous diets for strength, anaerobic, or aerobic exercise performance” (1). end public domain text

public domain text A second objection addresses the claim that land use for animal-based food production contributes to pollution and greenhouse gas emissions and is inefficient in terms of nutrient delivery. Berners-Lee et al. point out that animal nutrition from grass, pasture, and silage comes partially from land that cannot be used for other purposes, such as producing food directly edible by humans or for other ecosystem services such as biofuel production. Consequently, nutritional losses from such land use do not fully translate into losses of human-available nutrients (3). end public domain text

annotated text Paraphrase. Tran has paraphrased the information as support. Though she still cites the source, she has changed the words to her own, most likely to condense a larger amount of original text or to make it more accessible. end annotated text

public domain text While this objection may be correct, it does not address the fact that natural carbon sinks are being destroyed to increase agricultural land and, therefore, increase greenhouse gas emissions into the atmosphere. end public domain text

public domain text Another significant dissenting opinion is that transforming food production will place hardships on farmers and others employed in the food industry. Farmers and ranchers make a major investment in their own operations. At the same time, they support jobs in related industries, as consumers of farm machinery, customers at local businesses, and suppliers for other industries such as food processing (Schulz). Sparks reports that “livestock farmers are being unfairly ‘demonized’ by vegans and environmental advocates” and argues that while farming includes both costs and benefits, the costs receive much more attention than the benefits. end public domain text

FUTURE GENERATIONS

public domain text The EAT– Lancet Commission calls for a transformation in the global food system, implementing different core processes and feedback. This transformation will not happen unless there is “widespread, multi-sector, multilevel action to change what food is eaten, how it is produced, and its effects on the environment and health, while providing healthy diets for the global population” (Willett et al. 476). System changes will require global efforts coordinated across all levels and will require governments, the private sector, and civil society to share a common vision and goals. Scientific modeling indicates 10 billion people could indeed be fed a healthy and sustainable diet. end public domain text

annotated text Conclusion. While still using research-based sources as evidence in the concluding section, Tran finishes with her own words, restating her thesis. end annotated text

public domain text For the human race to have a sustainable future, massive changes in the way food is produced, processed, and distributed are necessary on a global scale. The required changes will affect nearly all aspects of life, including not only world hunger but also health and welfare, land use and habitats, water quality and availability, energy use and production, greenhouse gas emissions and climate change, economics, and even cultural and social values. These changes may not be popular, but they are imperative. They are also achievable. The human race must turn to sustainable food systems that provide healthy diets with minimal environmental impact, starting now. end public domain text

annotated text Sources. Note two important aspects of the sources chosen: 1) They represent a range of perspectives, and 2) They are all quite current. When exploring a contemporary topic, it is important to avoid research that is out of date. end annotated text

Works Cited

Barnard, Neal. “How Eating More Plants Can Save Lives and the Planet.” Physicians Committee for Responsible Medicine , 24 Jan. 2019, www.pcrm.org/news/blog/how-eating-more-plants-can-save-lives-and-planet. Accessed 6 Dec. 2020.

Berners-Lee, M., et al. “Current Global Food Production Is Sufficient to Meet Human Nutritional Needs in 2050 Provided There Is Radical Societal Adaptation.” Elementa: Science of the Anthropocene , vol. 6, no. 52, 2018, doi:10.1525/elementa.310. Accessed 7 Dec. 2020.

Chai, Bingli Clark, et al. “Which Diet Has the Least Environmental Impact on Our Planet? A Systematic Review of Vegan, Vegetarian and Omnivorous Diets.” Sustainability , vol. 11, no. 15, 2019, doi: underline 10.3390/su11154110 end underline . Accessed 6 Dec. 2020.

Curnow, Mandy. “Managing Manure to Reduce Greenhouse Gas Emissions.” Government of Western Australia, Department of Primary Industries and Regional Development, 2 Nov. 2020, www.agric.wa.gov.au/climate-change/managing-manure-reduce-greenhouse-gas-emissions. Accessed 9 Dec. 2020.

Gray, Richard. “Why the Vegan Diet Is Not Always Green.” BBC , 13 Feb. 2020, www.bbc.com/future/article/20200211-why-the-vegan-diet-is-not-always-green. Accessed 6 Dec. 2020.

Hamilton, Bruce. “Food and Our Climate.” Sierra Club, 2014, www.sierraclub.org/compass/2014/10/food-and-our-climate. Accessed 6 Dec. 2020.

Hertwich. Edgar G., et al. Assessing the Environmental Impacts of Consumption and Production. United Nations Environment Programme, 2010, www.resourcepanel.org/reports/assessing-environmental-impacts-consumption-and-production.

Lusk, Jayson L., and F. Bailey Norwood. “Some Economic Benefits and Costs of Vegetarianism.” Agricultural and Resource Economics Review , vol. 38, no. 2, 2009, pp. 109-24, doi: 10.1017/S1068280500003142. Accessed 6 Dec. 2020.

Lynch Heidi, et al. “Plant-Based Diets: Considerations for Environmental Impact, Protein Quality, and Exercise Performance.” Nutrients, vol. 10, no. 12, 2018, doi:10.3390/nu10121841. Accessed 6 Dec. 2020.

Münter, Leilani. “Why a Plant-Based Diet Will Save the World.” Health and the Environment. Disruptive Women in Health Care & the United States Environmental Protection Agency, 2012, archive.epa.gov/womenandgirls/web/pdf/1016healththeenvironmentebook.pdf.

Purdy, Chase. “Being Vegan Isn’t as Good for Humanity as You Think.” Quartz , 4 Aug. 2016, qz.com/749443/being-vegan-isnt-as-environmentally-friendly-as-you-think/. Accessed 7 Dec. 2020.

Schulz, Lee. “Would a Sudden Loss of the Meat and Dairy Industry, and All the Ripple Effects, Destroy the Economy?” Iowa State U Department of Economics, www.econ.iastate.edu/node/691. Accessed 6 Dec. 2020.

Sierra Club. “Agriculture and Food.” Sierra Club, 28 Feb. 2015, www.sierraclub.org/policy/agriculture/food. Accessed 6 Dec. 2020.

Sparks, Hannah. “Veganism Won’t Save the World from Environmental Ruin, Researchers Warn.” New York Post , 29 Nov. 2019, nypost.com/2019/11/29/veganism-wont-save-the-world-from-environmental-ruin-researchers-warn/. Accessed 6 Dec. 2020.

Willett, Walter, et al. “Food in the Anthropocene: The EAT– Lancet Commission on Healthy Diets from Sustainable Food Systems.” The Lancet, vol. 393, no. 10170, 2019. doi:10.1016/S0140-6736(18)31788-4. Accessed 6 Dec. 2020.

World Health Organization. “Malnutrition.” World Health Organization, 1 Apr. 2020, www.who.int/news-room/fact-sheets/detail/malnutrition. Accessed 8 Dec. 2020.

World Health Organization. “Obesity and Overweight.” World Health Organization, 1 Apr. 2020, www.who.int/news-room/fact-sheets/detail/obesity-and-overweight. Accessed 8 Dec. 2020.

World Wildlife Fund. Appetite for Destruction: Summary Report. World Wildlife Fund, 2017, www.wwf.org.uk/sites/default/files/2017-10/WWF_AppetiteForDestruction_Summary_Report_SignOff.pdf.

World Wildlife Fund and Knorr Foods. Future Fifty Foods. World Wildlife Fund, 2019, www.wwf.org.uk/sites/default/files/2019-02/Knorr_Future_50_Report_FINAL_Online.pdf.

“World Population by Year.” Worldometer , www.worldometers.info/world-population/world-population-by-year/. Accessed 8 Dec. 2020.

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Animal Essay

what happens in spring animals in spring Book

500 Words Essay on Animal

Animals carry a lot of importance in our lives. They offer humans with food and many other things. For instance, we consume meat, eggs, dairy products. Further, we use animals as a pet too. They are of great help to handicaps. Thus, through the animal essay, we will take a look at these creatures and their importance.

Types of Animals

First of all, all kinds of living organisms which are eukaryotes and compose of numerous cells and can sexually reproduce are known as animals. All animals have a unique role to play in maintaining the balance of nature.

A lot of animal species exist in both, land and water. As a result, each of them has a purpose for their existence. The animals divide into specific groups in biology. Amphibians are those which can live on both, land and water.

Reptiles are cold-blooded animals which have scales on their body. Further, mammals are ones which give birth to their offspring in the womb and have mammary glands. Birds are animals whose forelimbs evolve into wings and their body is covered with feather.

They lay eggs to give birth. Fishes have fins and not limbs. They breathe through gills in water. Further, insects are mostly six-legged or more. Thus, these are the kinds of animals present on earth.

Importance of Animals

Animals play an essential role in human life and planet earth. Ever since an early time, humans have been using animals for their benefit. Earlier, they came in use for transportation purposes.

Further, they also come in use for food, hunting and protection. Humans use oxen for farming. Animals also come in use as companions to humans. For instance, dogs come in use to guide the physically challenged people as well as old people.

In research laboratories, animals come in use for drug testing. Rats and rabbits are mostly tested upon. These researches are useful in predicting any future diseases outbreaks. Thus, we can protect us from possible harm.

Astronomers also use animals to do their research. They also come in use for other purposes. Animals have use in various sports like racing, polo and more. In addition, they also have use in other fields.

They also come in use in recreational activities. For instance, there are circuses and then people also come door to door to display the tricks by animals to entertain children. Further, they also come in use for police forces like detection dogs.

Similarly, we also ride on them for a joyride. Horses, elephants, camels and more come in use for this purpose. Thus, they have a lot of importance in our lives.

Get the huge list of more than 500 Essay Topics and Ideas

Conclusion of Animal Essay

Thus, animals play an important role on our planet earth and in human lives. Therefore, it is our duty as humans to protect animals for a better future. Otherwise, the human race will not be able to survive without the help of the other animals.

FAQ on Animal Essay

Question 1: Why are animals are important?

Answer 1: All animals play an important role in the ecosystem. Some of them help to bring out the nutrients from the cycle whereas the others help in decomposition, carbon, and nitrogen cycle. In other words, all kinds of animals, insects, and even microorganisms play a role in the ecosystem.

Question 2: How can we protect animals?

Answer 2: We can protect animals by adopting them. Further, one can also volunteer if one does not have the means to help. Moreover, donating to wildlife reserves can help. Most importantly, we must start buying responsibly to avoid companies which harm animals to make their products.

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Tran, H., A. Schlageter-Tello, A. Caprez, P. S. Millerm M. B. Hall, W. P. Weiss, and P. J. Kononoff. 2020. Development of feed composition tables using a statistical screening procedure. J. Dairy Sci. 103:P3786-3803. doi:10.3168/jds.2019-16702
Schlageter-Tello, A., G. C. Fahey, T. Freel, L. Koutsos, P. S. Miller, and W. P. Weiss. 2020. ASAS-NANP Symposium: Ruminant/Nonruminant Feed Composition: Challenges and opportunities associated with creating large feed ingredient composition tables. J. Anim. Sci. 98. doi:10.1093/jas/skaa240
Menendez III, H. M. and L. O. Tedeschi. 2020. The characterization of the cow-calf, stocker and feedlot cattle industry water footprint to assess the impact of livestock water use sustainability. J. Agric. Sci. doi:10.1017/S0021859620000672
Mark D. Hanigan and Veridiana L. Daley. 2020. Use of Mechanistic Nutrition Models to Identify Sustainable Food Animal Production. Annu. Rev. Anim. Biosci. 8:355-376. doi:10.1146/annurev-animal-021419-083913
Daley, V. L., L. E. Armentano, P. J. Kononoff, and M. D. Hanigan. 2019. Modeling fatty acids for dairy cattle: models to predict total fatty acid concentration and fatty acid digestion of feedstuffs. J. Dairy Sci. 103:6982-6999. doi:10.3168/jds.2019-17407
C.F Nicholson, A.R.P. Simões, P.A. LaPierre, M.E. Van Amburgh. 2019. ASN-ASAS Symposium: Future of Data Analytics in Nutrition: Modeling complex problems with system dynamics: applications in animal agriculture. J. Anim. Sci. 97:1903–1920. doi:10.1093/jas/skz105
L.O. Tedeschi. ASN-ASAS Symposium: Future of Data Analytics in Nutrition: Mathematical modeling in ruminant nutrition: approaches and paradigms, extant models, and thoughts for upcoming predictive analytics. J. Anim. Sci. 7:1921–1944. doi:10.1093/jas/skz092
Daley, V. L., Dye, C., Bogers, S. H., Akers, R. M., Rodriguez, F. C., Cant, J. P., Doelman, J., Yoder, P., Kumar, K., Webster, D., Hanigan, M. D. 2018. Bovine mammary gland biopsy techniques. J. Vis. Exp. 142:e58602. doi:10.3791/58602.
R. R. White, Y. Roman-Garcia, J. L. Firkins, P. Kononoff, M.J. VandeHaar, H. Tran, T. McGill, R. Garnett, M.D. Hanigan. 2017. Evaluation of the National Research Council (2001) dairy model and derivation of new prediction equations. 2. Rumen degradable and undegradable protein. J. Dairy Sci. 100:3611-3627. doi:10.3168/jds.2015-10801
R. R. White, Y. Roman-Garcia, J. L. Firkins, M.J. VandeHaar, L.E. Armentano, W.P. Weiss, T. McGill, R. Garnett, M.D. Hanigan. 2017. Evaluation of the National Research Council (2001) dairy model and derivation of new prediction equations. 1. Digestibility of fiber, fat, protein, and nonfiber carbohydrate. J. Dairy Sci. 100:3591-3610. doi:10.3168/jds.2015-10800
J. P. McNamara, M. D. Hanigan, R. R. White. 2016. Invited review: Experimental design, data reporting, and sharing in support of animal systems modeling research. J. Dairy Sci. 99:9355–9371. doi:10.3168/jds.2015-10303
R. R. White, Y. Roman-Garcia, J. L. Firkins. 2016. Meta-analysis of postruminal microbial nitrogen flows in dairy cattle. II. Approaches to and implications of more mechanistic prediction. J. Dairy Sci. 99:7932-7944. doi:10.3168/jds.2015-10662
Y. Roman-Garcia, R. R. White, J. L. Firkins. 2016. Meta-analysis of postruminal microbial nitrogen flows in dairy cattle. I. Derivation of equations. J. Dairy Sci. 99:7918-7931. doi:10.3168/jds.2015-10661
R.R. White, M.D. Hanigan. 2016. Modeling cross species intake responses to environmental stress. J. Agric. Sci. 154:136-150. doi:10.1017/S0021859615001033
R. R. White, P. S. Miller, M. D. Hanigan. 2015. Evaluating equations estimating change in swine feed intake during heat and cold stress. J. Anim. Sci. 93:5395–5410. doi:10.2527/jas2015-9220

print of a goat on hind legs with arrow in its side eating from a tall plant

Animals self-medicate with plants − behavior people have observed and emulated for millennia

Research Scholar, Classics and History and Philosophy of Science, Stanford University

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Adrienne Mayor does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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When a wild orangutan in Sumatra recently suffered a facial wound, apparently after fighting with another male, he did something that caught the attention of the scientists observing him.

The animal chewed the leaves of a liana vine – a plant not normally eaten by apes. Over several days, the orangutan carefully applied the juice to its wound, then covered it with a paste of chewed-up liana. The wound healed with only a faint scar. The tropical plant he selected has antibacterial and antioxidant properties and is known to alleviate pain, fever, bleeding and inflammation.

The striking story was picked up by media worldwide. In interviews and in their research paper , the scientists stated that this is “the first systematically documented case of active wound treatment by a wild animal” with a biologically active plant. The discovery will “provide new insights into the origins of human wound care.”

left: four leaves next to a ruler. right: an orangutan in a treetop

To me, the behavior of the orangutan sounded familiar. As a historian of ancient science who investigates what Greeks and Romans knew about plants and animals, I was reminded of similar cases reported by Aristotle, Pliny the Elder, Aelian and other naturalists from antiquity. A remarkable body of accounts from ancient to medieval times describes self-medication by many different animals. The animals used plants to treat illness, repel parasites, neutralize poisons and heal wounds.

The term zoopharmacognosy – “animal medicine knowledge” – was invented in 1987. But as the Roman natural historian Pliny pointed out 2,000 years ago, many animals have made medical discoveries useful for humans. Indeed, a large number of medicinal plants used in modern drugs were first discovered by Indigenous peoples and past cultures who observed animals employing plants and emulated them.

What you can learn by watching animals

Some of the earliest written examples of animal self-medication appear in Aristotle’s “ History of Animals ” from the fourth century BCE, such as the well-known habit of dogs to eat grass when ill, probably for purging and deworming.

Aristotle also noted that after hibernation, bears seek wild garlic as their first food. It is rich in vitamin C, iron and magnesium, healthful nutrients after a long winter’s nap. The Latin name reflects this folk belief: Allium ursinum translates to “bear lily,” and the common name in many other languages refers to bears.

medieval image of a stag wounded by a hunter's arrow, while a doe is also wounded, but eats the herb dittany, causing the arrow to come out

Pliny explained how the use of dittany , also known as wild oregano, to treat arrow wounds arose from watching wounded stags grazing on the herb. Aristotle and Dioscorides credited wild goats with the discovery. Vergil, Cicero, Plutarch, Solinus, Celsus and Galen claimed that dittany has the ability to expel an arrowhead and close the wound. Among dittany’s many known phytochemical properties are antiseptic, anti-inflammatory and coagulating effects.

According to Pliny, deer also knew an antidote for toxic plants: wild artichokes . The leaves relieve nausea and stomach cramps and protect the liver. To cure themselves of spider bites, Pliny wrote, deer ate crabs washed up on the beach, and sick goats did the same. Notably, crab shells contain chitosan , which boosts the immune system.

When elephants accidentally swallowed chameleons hidden on green foliage, they ate olive leaves, a natural antibiotic to combat salmonella harbored by lizards . Pliny said ravens eat chameleons, but then ingest bay leaves to counter the lizards’ toxicity. Antibacterial bay leaves relieve diarrhea and gastrointestinal distress. Pliny noted that blackbirds, partridges, jays and pigeons also eat bay leaves for digestive problems.

17th century etching of a weasel and a basilisk in conflict

Weasels were said to roll in the evergreen plant rue to counter wounds and snakebites. Fresh rue is toxic. Its medical value is unclear, but the dried plant is included in many traditional folk medicines. Swallows collect another toxic plant, celandine , to make a poultice for their chicks’ eyes. Snakes emerging from hibernation rub their eyes on fennel. Fennel bulbs contain compounds that promote tissue repair and immunity.

According to the naturalist Aelian , who lived in the third century BCE, the Egyptians traced much of their medical knowledge to the wisdom of animals. Aelian described elephants treating spear wounds with olive flowers and oil . He also mentioned storks, partridges and turtledoves crushing oregano leaves and applying the paste to wounds.

The study of animals’ remedies continued in the Middle Ages. An example from the 12th-century English compendium of animal lore, the Aberdeen Bestiary , tells of bears coating sores with mullein . Folk medicine prescribes this flowering plant to soothe pain and heal burns and wounds, thanks to its anti-inflammatory chemicals.

Ibn al-Durayhim’s 14th-century manuscript “ The Usefulness of Animals ” reported that swallows healed nestlings’ eyes with turmeric , another anti-inflammatory. He also noted that wild goats chew and apply sphagnum moss to wounds, just as the Sumatran orangutan did with liana. Sphagnum moss dressings neutralize bacteria and combat infection.

Nature’s pharmacopoeia

Of course, these premodern observations were folk knowledge, not formal science. But the stories reveal long-term observation and imitation of diverse animal species self-doctoring with bioactive plants. Just as traditional Indigenous ethnobotany is leading to lifesaving drugs today , scientific testing of the ancient and medieval claims could lead to discoveries of new therapeutic plants.

Animal self-medication has become a rapidly growing scientific discipline. Observers report observations of animals, from birds and rats to porcupines and chimpanzees , deliberately employing an impressive repertoire of medicinal substances. One surprising observation is that finches and sparrows collect cigarette butts . The nicotine kills mites in bird nests. Some veterinarians even allow ailing dogs, horses and other domestic animals to choose their own prescriptions by sniffing various botanical compounds.

Mysteries remain . No one knows how animals sense which plants cure sickness, heal wounds, repel parasites or otherwise promote health. Are they intentionally responding to particular health crises? And how is their knowledge transmitted? What we do know is that we humans have been learning healing secrets by watching animals self-medicate for millennia.

Zoopharmacognosy
Animal behavior
Self-medication
Phytochemicals
Ancient world

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Food environment and its effects on human nutrition and health.

1. Introduction

2. an overview of the published articles, author contributions, conflicts of interest, list of contributions.

Zhou, B.; Zhang, Y.; Hiesmayr, M.; Gao, X.; Huang, Y.; Liu, S.; Zhao, Y.; Cui, Y.; Zhang, L.; Wang, X.; Nutrition Day Chinese Working Goup. Dietary provision, GLIM-defined malnutrition and their association with clinical outcome: Results from the first decade of nutrition Day in China. Nutrients 2024 , 16 (4), 569. https://doi.org/10.3390/nu16040569 .
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Mondragon Portocarrero, A.d.C.; Miranda Lopez, J.M. Food Environment and Its Effects on Human Nutrition and Health. Nutrients 2024 , 16 , 1733. https://doi.org/10.3390/nu16111733

Mondragon Portocarrero AdC, Miranda Lopez JM. Food Environment and Its Effects on Human Nutrition and Health. Nutrients . 2024; 16(11):1733. https://doi.org/10.3390/nu16111733

Mondragon Portocarrero, Alicia del Carmen, and Jose Manuel Miranda Lopez. 2024. "Food Environment and Its Effects on Human Nutrition and Health" Nutrients 16, no. 11: 1733. https://doi.org/10.3390/nu16111733

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Availability, in a sustained manner, of desired type and quantity of animal feed and its feeding is the foundation of livestock production system. Animal feed availability and animal feeding is a multi-faceted theme. It influences all livestock sub-sectors across production systems. It also has far reaching effects on human nutrition, poverty ...
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The different types of nutrition in animals include: Filter Feeding: It is a process of acquiring nutrients from particles suspended in water. This method is commonly used by fish. Deposit feeding: It is the process of obtaining nutrients from particles suspended in the soil. Earthworms use this method to take nutrition. Fluid feeding: When one ...
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Scientific papers published on animal nutrition. A study in Zoo Biology analysed the nutritional contents & composition of a colony of Polyrhachis dives ants - key prey in the diet of the critically endangered Chinese pangolin:. Colony consisted mostly of adults, but also pupae, larvae & eggs;. High protein & chitin, low fat & formic acid identified in both colony & adult ants;
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Melrose animal sanctuary owner arrested on fraud charges
MELROSE, Fla. (WCJB) - Putnam County Sheriff's deputies arrested the owner of an animal sanctuary in Melrose on a variety of fraud charges. Putnam County Sheriff's deputies say they arrested Edna Elaine West, 61, Friday morning after receiving a warrant from the Department of Agriculture. Deputies say West solicited funds for her ...

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I. Introduction to Nutrition

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Maize green forage as a partial replacement for lettuce in the diet of West Indian manatee Trichechus manatus (Krajda et al., 2023)

Multi-criteria study on a change to a fruit-free diet in Cebidae and Cercopithecidae (Viallard et al., 2023)

Fasted and furious? Considerations on the use of fasting days in large carnivore husbandry (Kleinlugtenbelt et al., 2023)

The behavioural effects of feeding lean meat vs whole rabbit carcasses to zoo jaguars Panthera onca (Enemark et al., 202 3)

Nutritional effect of feeding enrichment using bamboo Pleioblastus spp. in zoo-kept Asian elephants Elephas maximus ( Tsuchiya et al., 2023)

Diet impacts the structure and function of the bacterial community in the gastrointestinal tract of a sloth bear (Loudon et al., 2022)

Effects of Storage Time and Thawing Method on Selected Nutrients in Whole Fish for Zoo Animal Nutrition (Gimmel et al., 2022)

Dietary protein requirement for captive juvenile green turtles ( Chelonia mydas ) (Jualaong et al., 2022)

Feeding regimen and growth comparison in two related African painted dog Lycaon pictus litters (Cloutier et al., 2022)

Keeping the golden mantella golden: The effect of dietary carotenoid supplementation and UV provision on the colouration and growth of Mantella aurantiaca (Newtons-Youens, Michaels & Preziosi, 2022)

Assessment of Feeding Behavior of the Zoo-Housed Lesser Anteater ( Tamandua tetradactyla ) and Nutritional Values of Natural Prey (Zárate et al., 2021)

New insights into dietary management of polar bears ( Ursus maritimus ) and brown bears ( U. arctos ) (Robbins et al., 2021)

Colony composition and nutrient analysis of Polyrhachis dives ants, a natural prey of the Chinese pangolin ( Manis pentadactyla ) (Xu et al., 2021)

Investigating food preference in zoo-housed meerkats (Brox et al., 2021)

A modified diet to support conservation of the Atala hairstreak butterfly ( Eumaeus atala Poey) (Braatz et al., 2021)

Ensiling of maple leaves and its use in winter nutrition of mantled guereza ( Colobus guereza ) (Lasek et al., 2021)

Grading fecal consistency in an omnivorous carnivore, the brown bear: Abandoning the concept of uniform feces (De Cuyper et al., 2021)

Circulating nutrients and hematological parameters in managed African elephants ( Loxodonta Africana ) over a 1‐year period (Wood et al., 2020)

Daily lettuce supplements promote foraging behavior and modify the gut microbiota in captive frugivores (Greene et al., 2020).

Dietary management of hypercholesterolemia in a bachelor group of zoo-housed Slender-tailed meerkats ( Suricata suricatta ) (Dobbs et al., 2020)

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Nutritional physiology and ecology of wildlife in a changing world

Kathryn S. Peiman

Steven J. Cooke

Introduction

Human-induced environmental changes and their effects on nutrition

Climate change