Part 2: Understanding the interface between humans and animals

6 Planetary Health and Food Animal Production

Authors: Hurnik, D.

After reading this chapter you should be aware of:

  • Wildlife stuff GOES HERE
  • Human Interaction with Food production STUFF GOES HERE
  • List the benefits of biodiversity to human health​
  • Explain how local and planetary biodiversity are sustained​
  • Describe how human activity contributes to loss of biodiversity​
  • Provide examples on how loss of biodiversity impacts negatively on human health
  • Human Interaction with Food Production STUFF GOES HERE

History of Animal Agriculture

Life on the surface of the earth depends on energy from the sun. The first life forms, once established, began to grow exponentially and so inevitably overshadowed each other in the quest for light.  Thus began a fight for sunlight and survival.  Competition for resources remains a common theme that drives all animal life and human civilization to this day.


The initial competition for sunlight caused early life forms to form solid structures like cellulose and lignin so that they can  grow up over each other to reach sunlight sun.  New innovative life forms began consuming plant material instead depending on photosynthesis.  To optimally access many plants, these herbivores needed to be mobile, and so animals evolved to move to their food source.  The variety of herbivores that swim, fly and walk today are a consequence of the intense competition for food.   Other animals rather than continually searching for leaves just found it easier to eat the herbivores.  Carnivores are part an ecological balance where the sun’s energy is captured and shared in a food chain where every life form is looking to survive and reproduce.   Homo Sapiens arose in this distributive energy ecosystem


Humans have become the most widespread competitor for resources and have settled almost everywhere in the world from the arctic where no plants grow, to tropical jungles to deserts.  The advantage that humans have over other species is the ability to communicate and work together.   The evolution of language, initially spoken, then pictorial, and now written, requires a large brain and a more intensive nutritional demand. Humans evolved to survive on a variety of foods and ecosystems.  We can exist on an all-animal diet[1] or primarily on plants when living in lush vegetation. We evolved an ability to run distances and outlast prey and a metabolism to endure periods of hunger when prey wasn’t found.


As humans started to work together, we taught each other how to hunt animals much more efficiently.  Examples still exist of these early hunting techniques [figure 1], and we became the most effective carnivore on earth.   As our population grew humans fought over optimal land and learned to trade resources, all activities in which we still engage.


When prey was scarce, early hunter gather societies found a way to corral and confine animals [figure 2], and so livestock farming began.  All our livestock species had their origin in wildlife.   Canadian cattle began as wild European aurochs[2] (Bos primigenius) pigs as wild eurasian pigs[3] (Sus Scrofa), and chickens as wild birds traded from Asia[4].  Through natural selection we have domesticated these species to improve their temperament – so they are less likely to kill us – and to better meet our nutritional needs.   Historically we have increased their fat content [Figure 3] to be a better source of energy and enlarged their muscles for a source of protein.  This continual refinement of our livestock’s genetic base continues to this day[5].


We found nutrition could come from animals without having to killing them   Milk designed to grow offspring is nutritionally dense, and even if we were lactose intolerant, the benefits outweighed the discomfort.[6]  Similarly eggs became a favoured nutritionally dense food giving a survival advantage to societies that found ways to domesticate poultry and keep them laying.


Humans also found a myriad of ways to preserve animal-based foods to carry over times of famine.  Early nomads carried meat under the saddle of their horses where both drying and the salt from the sweating horse would preserve the meat[7].   Heavy salt can prevent bacterial growth and with natural fermentation we can create the dry cured meat products that we still eat today[8].  Pickling in low pH, fermenting, smoking, cooking, drying and freezing techniques were discovered to preserve animal based foods for consumption later.    These techniques form the basis of our culinary and charcuterie skills we take pride in.


The value of animal-based foods goes is deeper than the nutrition it provides.   Humans still enjoy hunting and fishing, and we pay particular attention to food preparation to impress others.   Bonding around food experiences whether it’s the raising, obtaining or preparation of foods is an emotionally satisfying activity that creates friendships and harmony.  A lack of food and inequitable distribution leads to strife.




The production of food from animals is not separated from the human’s competition for resources and survival.  Animals, once slaughtered, are sold as meat products, and once packaged, meat is generally considered a commodity.   Just like coal, metals, and wood products, meat is traded on an open market   Butchers buy animals to process and farmers compete to supply them.    The producer with the lowest cost is the most profitable.  It is difficult for butchers to raise prices of their meat if another can supply it for a lower price. Humans retain a universal and fundamental motivation to never pay more than we need to.


This market approach forms the basis of modern agriculture and farmers struggling to survive are continually looking for efficiency and cost savings.   The net effect to society is an ever-present supply of food ingredients at the lowest cost possible. This food production system has made our human population to grow exponentially and reduce starvation episodes.  Our civilization less has food production crises[9], but we do retain a distribution problem.


The most expensive cost of raising a farm animal is feed.  In pig and poultry production 70-80% of the production cost is feed[10] and the conversion of feed to meat is the metric most closely monitored by livestock producers. Chasing a better feed conversion ratio is the greatest driver of the change we see in modern livestock today.   Fat is more energy dense than muscle and and so fatter animals needs more feed.   In the pursuit of feed efficiency, we are selecting our farm animal to be leaner.   If at the same time an animal grows faster, the producer can sell more animals annually and animals reaching market age sooner use less feed for maintenance (metabolism and mobility) and again require less feed.    Consequently, modern agriculture has been selecting faster growing and leaner animals[11].


Starting from a traditional multi species mixed farm, producers found it more efficient to specialize and become exceptionally good at raising their preferred species.  Most commercial farms today focus one livestock species and can negotiate supplies at better prices and gain economy of scale through increasing farm size.  The competition for farm survival resulted in fewer, larger increasingly specialized farms which raise livestock indoors[12].


Farm animals are brought under a roof for several reasons starting with shelter from cold.  Cold animals will eat more feed to stay warm and raising them in their thermoneutral zone minimizes feed cost.   Animals indoors are at less risk of predation and disease coming from wildlife.  Some zoonotic diseases such a trichinosis can be controlled when animals are indoors as are diseases such as influenza, leptospirosis and tuberculosis which can spread from wildlife.



Further feed efficiency can be found in eliminating endemic diseases.  Most pig and poultry production use principles of Specific Pathogen Free (SPF) production where pathogens are eliminated where possible.  Starting with the breeding stock down to commercial farms if pathogens are removed, disease loss can be eliminated.  Some diseases resist elimination and so vaccination and parasite control is another foundational strategy on most farms.    Some countries have eliminated severe animal diseases such as Foot and Mouth Disease which can affect many livestock species, however in some regions it remains endemic[13].   Animal diseases are still spreading internationally, particularly African Swine Fever, which  survives months in meat products and has spread worldwide save the continental Americas and Oceania. This disparity of health status results in severe restrictions on trading of animals or meats between regions.  Our cultural differences and emotional attachments to food products drives people to smuggle meats over borders[14] and requires intensive border protection and inspection.


Early in the intensification of animal production the use of antibiotics was found to be particularly valuable because controlling subclinical disease and changing on enteric flora improved growth rate and feed efficiency[15].    Other pharmaceuticals were found that could increase growth rates and muscling to bring economic advantages.   Anabolics such as zeranol[16] and Beta agonists such as Ractopamine[17] have been approved for food animal use in North America. For consumers looking for the lowest price for meat, antimicrobial drugs and pharmaceuticals are powerful economic tools.



The same economy of scale that producers used to reduce their cost applies to slaughter and meat processing companies as well.  Larger processors in animal dense areas have significant cost advantages, and with refrigeration can transport meat in large volumes to consumers in large cities and countries with high populations.   This evolution coinciding with industrialization profoundly shaped North American society and is well described[18].  Large processing plants can invest in technology that can utilize every part of the animal and package it for sale anywhere in the world that will give the best price.  The modern pig in Canada is sold in worldwide and is processed into a myriad of cuts[19].  [figure 4 – cut chart] Again, competition for profitability has led to small number of high volume processing plants.  The intense competition survival by producers and processors to stay in business gives Homo sapiens globally a lower real cost of food.


There are disadvantages of open market economics for food production, and other systems have been tried.   In centrally planned economies where technocrats set price and production targets, political influence controlled access to food.  The resulting corruption and inefficiency eventually returned market economics. Governments worldwide do try to soften the rough edges of market economics. In Canada we have a supply managed system production for poultry and dairy foods which supports local producers, but they require border restrictions to keep cheaper imports out.



Challenges of Animal Agriculture


Despite the abundance our food production system, there are always drawbacks and opportunities to improve food production .


Nutrition and Health


Animal based protein may that they negatively impact our health.   When we were cold, starving, and depended on manual labour, animal proteins and particularly fats were highly valued because of their nutrient density.  As we mechanized, both obesity and heart disease became a concern. Low fat and increased polyunsaturated intake nutritional recommendations urged people away animal based foods.   Animal agriculture responded by reducing the fat content of livestock-based foods.  Leaner cuts of meat were marketed, which coincided well with the search for feed efficiency.   A consequence of leaner cuts with less fat is reduced tenderness and flavour. We can now find moisture enhanced meat cuts in the super market[20],[21], along recommendations not overcook meats as attempt to improve the eating experience. Niche marketing of  flavourful  “heritage breeds” such as Berkshire hogs or Wagu raised cattle which carry more intra muscular fat are marketed for their superior taste.


As our understanding of heart disease has become more sophisticated, role of animal-based fats is not as clear and some authors tout the benefits of animal fats and recommend the nutrient density of animals based foods.[22]


There are more recent concerns around the carcinogenicity of meats, particularly processed meat products preserved with nitrites and other compounds   Preserving meats with wood smoke reduces bacterial growth, but smoke (like campfires and wood stoves) has creosotes and nitrites convert to nitrosamines during the cooking process[23].


The health risk of animal-based foods remains intensely debated with varied motivations.[24].



Animal diseases can spread to people via animals and their food products.  Some bacteria such as salmonella strains cause enteric disease in both animal and human hosts.   One of the first diseases that animal agriculture eliminated from domestic animal populations were ones causing significant human disease.   Brucellosis and tuberculosis were eliminated from domestic livestock populations in North America in the previous century through veterinary public health initiatives.  Coupled with milk pasteurization, both diseases have been well controlled.   The infectious organisms still exist in wildlife. Similarly, Trichinella spiralis infections in pigs were historically a risk when eating pork; today moving production indoors and away from wildlife has controlled the risk in commercial  pork production.    Consequently, pork cooking recommendations have relaxed, recommending leaving an “hint of pink” to enhance the eating experience[25].


Gut pathogens such as salmonella strains, O157 E. coli, and Campylobacter species can contaminate animal carcasses at slaughter and if the resultant animal food products are not cooked throughly, can result in human disease.  The risk is mitigated by food safety plans at slaughter that minimize cross contamination of meat.    One consequence of larger processing plants is that contamination in one plant can have a large impact[26].   Food inspection processes provided by the federal Canadian Food Inspection Agency (CFIA) use prevention principles centred around Hazard Analysis and Critical Control Points (HAACP) to evaluate food safety plans in federally inspected meat processing plants[27]. These plans these require significant investment in refrigeration, sanitation, and traceability of food products.   Federally inspected meat products will have federal markings and certificates of inspection (figure 5).   Smaller scale processing plants may be licensed provincially, and those products can only marketed within the province.   Provincial requirements may differ from federal, and any associated outbreak will be limited to that province.  If animals are slaughtered directly on a farm the meat may be consumed by that household, but if it is sold or traded with others it must be inspected either provincially or federally.


Some zoonotic hazards can arise from improper storage or preservation.   If meat products are insufficiently refrigerated, bacteria from any source can grow to quantities posing a health threat.  Federal inspection standards require cold chain verification prior to sale and modern food transportation have temperatures monitoring processes.  Food safety training and awareness at the consumer level can further mitigate hazards, but humans make mistakes and food-based problems will always pose potential risk to our health.





Antimicrobial resistance


Antimicrobial compounds in food production do bring an economic benefit; however, based on an understanding of antimicrobial resistance (AMR), there is a growing concern that widespread use of antimicrobial drugs may create a drug resistance problem for both human and veterinary medicine. Data shows that AMR carrying bacteria can be present on meat products, shed in animal manure and dust exiting animal facilities[28].   As response both industry and public health authorities have initiatives to mitigate this AMR risk to the Canadian public.   The Veterinary Drugs Directorate branch of Health Canada, which approves the use of veterinary drugs has recently (2018) removed all claims for antimicrobial drugs licensed for growth promotion and made all antimicrobial use in livestock directed by veterinary prescription[29].  Veterinarians have guidelines for prescribing antimicrobials to food animals and some veterinary regulatory bodies have mandated AMR training as part their continuing education requirements.  Nationally the veterinary profession has developed prudent use guidelines to reduce the risk AMR in livestock and have classified veterinary drugs based on their importance for human use[30], and the Canadian integrated program antimicrobial resistance surveillance (cipars) project continues to monitor AMR in Canadian food[31]


All antimicrobial and pharmaceutical use in food animals also has a requirement time passes from treatment until slaughter.  This withdrawal time is to ensure any remaining residues of veterinary drugs fall below federal safety limits.   The maximum residual limits (MRLs) approved by Health Canada, are publicly available, and form the basis for the dosing, label claims and withdrawal times for veterinary drugs in Canada.[32]


Livestock producers similarly recognize concerns around antimicrobial use and have put into place quality assurance programs to ensure withdrawal times are met and that there is veterinary oversight of antimicrobial use.


AMR remains a major concern to some consumers and a further response by industry has been the growth of an ‘antibiotic free’ (ABF) animal production systems. To meet labelling requirements[33], participating producers do use not routine use of antimicrobial drugs when growing their animals.   If individual animals become infected, they can be treated, but they need to be identified and marketed as conventional animals.   ABF farms will use disease elimination and vaccination strategies to mitigate the need to routine prophylactic or metaphylactic antimicrobial use.   ABF farms consequently do have a higher cost of production and processors and consumers pay a premium price for these meat products.  What started as a niche market has become a regular choice alongside commodity meat products at retail.


Some consumers also have concerns about anabolic and other pharmaceuticals in the food chain. While these are also generally covered in most ABF claims, additional consumer concerns around herbicides and chemicals used in agriculture lead them to source organic or biodynamic meat products.  Organic certification[34] limits all chemical use which leads to a drop in crop productivity.  Organic livestock feeds are generally 2 to 3 times more expensive than conventional feeds.  Since feed is 70% or more the cost of raising livestock, organic meats tend to be more significantly more expensive.  Organic meats are a niche choice for motivated consumers.


Animal Welfare


The efficient production of livestock has been challenged by people who state that the animal’s needs are not considered.   Initial welfare recommendations were that animals we raise for food be given key freedoms, specifically: freedom from hunger, pain, fear, disease, given shelter and comfort and that they be allowed to express their natural behaviour.[35]   Moving animals inside has been successful in providing protection from the elements, predators, with the provision of ample feed animals aren’t hungry and they can grow efficiently.    The stocking density of animals in a pen or barn is generally optimized to provide maximum livestock throughput.  Like humans, farm animals will compete for feed and sleeping space, and in some cases such as poultry egg layers, gestating sows, or stanchioned dairy cattle are confined to small areas and their movement is restricted.   Animal welfare advocates argue that such confinement doesn’t allow animals to express their natural behaviour resulting frustrated or bored animals and ask for less confinement and an elimination of procedures such as tail docking, castration, dehorning and beak trimming.


The livestock Industry has responded by implementing welfare recommendations through national codes of practice[36].  Ongoing research looks for methods of implementation of welfare recommendation that do not reduce productivity and profitability.   For consumers who feel that is not moving fast enough, there are certified welfare programs that limit confinement or animal procedures[37].  These programs do have a higher cost of production and are so the meat and food products are sold to consumers for a premium.


Animal welfare concerns extend to transport and slaughter processes.  The Canadian Food Inspection agency oversees transportation and slaughter of livestock.  Slaughter requires the animal are stunned and unconscious prior to exsanguination which is required for food safety and aesthetic reasons.  Some religious slaughter prohibits stunning leading to some contention between religious and animal welfare principles[38].


There are consumers that avoid all animal food products not wanting to kill or exploit sentient life.  All food production though requires extensive rodent and pest control[39] with some methods such as poisons causing pain and slow death of targeted animals.   Just by our existence, regardless of what were eat, humans create negative welfare experience for other animal species and ecosystems.


Climate Change


Calculations on the impact of animal agriculture suggest that animals do contribute to greenhouse gas production, particularly methane.   Methane is generated from the decay and digestion of plant matter, and so ruminants such as cattle, sheep and goats who are herbivores release methane as they digest cellulose and plant matter.  Mono-gastric livestock, poultry and pigs generate less methane [figure 6].  The degree and amount of the contribution of livestock to climate change is under dispute.[40]


Livestock, particularly monogastrics (chickens and pigs) primarily eat foods that would normally not be used to feed people.   Soybeans are widely grown with most beans processed for oil, leaving the protein component, which humans generally do not consume, Pigs and poultry will efficiently convert that waste stream into foods we do consume.   Similarly, corn and grains are grown and further processed into subcomponents for human use.  Flour, corn starch, beer, fructose and more recently ethanol are derived from these crops.   Components not used for humans are fed to animals: wheat middlings, Distiller’s grains, as well as whole grains that don’t meet human quality standards are converted to meat through livestock.  If we remove livestock from the equation, these plant byproducts would be wasted.   Livestock are a valuable part of reducing food waste and efficient use of energy.



Future of Animal Agriculture


As a society we will continue to evolve our relationship with animal-based foods.   Niche markets featuring antibiotic free production, organic meats and welfare enhanced systems all exist and are competing for their place on the plate.

All livestock production methods have advantages and disadvantages.   Moving animal production back to extensive outdoor production gives animals more freedom but places them in contact with wildlife.  Pastured animals have a higher risk of contracting trichinella parasites, toxoplasmosis[41].  Regenerative agriculture where multiple animal species  are raised together in harmony with the soil has advantages[42], but requires motivated agricultural entrepreneurs willing to invest years building their farms.    Currently agriculture has worker shortages and to find enough farmers to supply food through smaller scale agriculture to feed 8 billion people may be difficult.  Efforts to force organic principles on a food production system has led to financial and political difficulties[43]  Wholesale change in food production needs to be done carefully.


Perhaps the most radical change to animal agriculture is the trend to grow meat in cell culture as opposed to living animals.   This technology would solve the welfare issues of raising sentient animals, but so far exists as an investment opportunity.  Whether it will prove to be as energy efficient as livestock converting 2kg of grain to 1 kg of meat and what proportion of consumers will chose cultured meats will remain to be seen.


Animal based foods have been with humans throughout our history, and they remain a significant source of nutrients and emotional comfort.   There currently is such variety of food choices that each person can chose based on their preferences.  The diversity of preferences will continue to drive innovation and evolution of food products.


[1] Nina Teicholz. The Fat Paradox: Good Health on a High-Fat Diet  Chapter 1. in The Big Fat Surprise, Simon and Schuster 2014

[2] Orlando, L. The first aurochs genome reveals the breeding history of British and European cattle. Genome Biol 16, 225 (2015).

[3] Bosse, Mirte, et al. “Untangling the hybrid nature of modern pig genomes: a mosaic derived from biogeographically distinct and highly divergent Sus scrofa populations.” Molecular ecology 23.16 (2014): 4089-4102.

[5] deMassender, Erin. Investigating Genomic Methods to Improve the Productivity of Canadian Dairy Goats. Diss. University of Guelph, 2022.

[6] Evershed, R.P., Davey Smith, G., Roffet-Salque, M. et al. Dairying, diseases and the evolution of lactase persistence in Europe. Nature 608, 336–345 (2022).

[7] Mongol War, Hunt, and Peace – FifteenEightyFour | Cambridge University Press://


[9] Joe Hasell and Max Roser (2013) – “Famines”. Published online at Retrieved from: ‘’ [Online Resource]



[12] Madec, F., Hurnik, D., Porphyre, V., & Cardinale, E. (2010). Good practices for biosecurity in the pig sector: Issues and options in developing and transition countries. FAO Animal Production and Health Paper No. 169. Italy: FAO.

[13] Animal Diseases – WOAH – World Organisation for Animal Health

[14]Madeleine Aggeler. TEXAS MONTHLY: Why Are Border Smugglers Trafficking Bologna?  September 2022 issue of Texas Monthly with the headline “A Bunch of Bologna.”

[15] W. J. Visek, The Mode of Growth Promotion by Antibiotics, Journal of Animal Science, Volume 46, Issue 5, May 1978, Pages 1447–1469,

[17]The facts regarding Ractopamine:

[18] Maureen Ogle, In Meat We Trust: An Unexpected History of Carnivore America, Houghton Mifflin  Harcourt, 2013

[20] Wendler KR, et al.Bacteriology and Meat Quality of Moisture Enhanced Pork from Retail Markets in CanadaJournal of Food Research; Vol. 6, No. 1; 2017

[21] Enhanced Meat – The Virtual Weber Bullet, `

[22] Jayne Buxton, Nutritional Score Card – Plants vs Animal Foods, in The Great Plant-Based  Con. Piatkus 2022.

[24] Jayne Buxton, Chapter 11, How a serving of Religion ended up on your plate, in The Great Plant-Based  Con. Piatkus 2022

[25] Cooked Color in Pork – Pork Information Gateway,

[26] Lone J, Huffman R. Building food safety into the company culture: a look at Maple Leaf Foods. Perspect Public Health. 2014 Jul;134(4):200-5. doi: 10.1177/1757913914532620. PMID: 24812255.

[27] The Food Safety Enhancement Program approach to a preventive control plan – Canadian Food Inspection Agency,

[28] Graham DW, Bergeron G, Bourassa MW, et al. Complexities in understanding antimicrobial resistance across domesticated animal, human, and environmental systems. Annals of the New York Academy of Sciences. 2019 Apr;1441(1):17-30. DOI: 10.1111/nyas.14036. PMID: 30924539; PMCID: PMC6850694.

[30] CVMA Guidelines for Veterinary Antimicrobial Use | Canadian Veterinary Medical Association,

[31] Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) –,

[34]Canadian Organic Standards – Canadian Food Inspection Agency,

[35] Webster AJ. Farm animal welfare: the five freedoms and the free market. Vet J. 2001 May;161(3):229-37. doi: 10.1053/tvjl.2000.0563. PMID: 11352481.

[36] Codes of Practice for the care and handling of farm animals,

[37] Global Animal Partnership: Animal Welfare Food Labeling Program,

[38] M. Haluk Anil, Religious slaughter: A current controversial animal welfare issue, Animal Frontiers, Volume 2, Issue 3, July 2012, Pages 64–67,

[39] Jayne Buxton, Chapter 9, The secret life of Vegan foods, and why a plant-only diet isn’t necessarily green, in The Great Plant-Based  Con. Piatkus 2022

[40] Jayne Buxton, Chapter 7 Emission Stories: The truth about C02, methane and those cow burps , in The Great Plant-Based  Con. Piatkus 2022

[41] Davies PR, Morrow WE, Deen J, Gamble HR, Patton S. Seroprevalence of Toxoplasma gondii and Trichinella spiralis in finishing swine raised in different production systems in North Carolina, USA. Prev Vet Med. 1998 Jul 17;36(1):67-76. doi: 10.1016/s0167-5877(98)00072-5. PMID: 9677628.

[42] Pollan Michael,  The Omnivore’s Dilemma, A natural History of Four Meals, The Penguin Press, 2006

[43] Sri Lanka’s organic farming disaster, explained – Vox,


Principles of Planetary Health Copyright © 2022 by the authors. All Rights Reserved.

Share This Book