Importance of Livestock to Humans

Livestock, or farmed animals such as sheep, goats, pigs and cows, are very important for humans, especially concerning their critical roles in food security and agricultural sustainability. However, livestock have also long been used as models to address numerous problems that occur during pregnancy in mammals, including humans, such as infertility, poor fetal growth and development, and premature birth. Of course, efficient production of offspring is a primary focus of livestock producers as it is often an important source of income.

Livestock & Food Security

In an editorial inScience, the journal of the American Association for the Advancement of Science, in 2014, Donald Kennedy, President Emeritus of Stanford University at the time, pointed out the critical need for increased funding for agricultural research because of the challenges associated with feeding the world’s rapidly expanding population, and he identified food security as a critical global challenge of the 21st century.^1-4

Food security is defined by the World Bank as “when all people, at all times, have physical and economic access to sufficient safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life.”⁴ Although the focus of discussions about food security is usually the developing world, where most population growth is expected to occur, food security is equally important for the developed world. Globally, food insecurity currently affects nearly a billion people, including 20 million children under five years of age who experience severe malnutrition, and is one of the “major causes of death and disability worldwide.”⁵ Similarly, in the developed world food security remains problematic. In the U.S., for example, 13.5 percent of households are currently classified as food insecure.⁶

Hunger is principally caused by poverty, which currently affects approximately 11.1 percent (13.7 percent for children under 18 years of age) of the American population.⁷ Thus, 36.8 million U.S. citizens live in poverty, which is nearly one and half times the total population of the 10 largest U.S. cities (25.5 million).⁸ In addition, 4.2 million American households live in extreme poverty, meaning their income is less than $2.15 per day per person, which is the same definition used by the World Bank for extreme poverty in the developing world.⁹

Food insecurity affects especially children because “[u]ndernutrition and malnutrition in childhood interfere with physical and mental development, thus compromising whole lives. Assuring adequate nutrition from an early age on is therefore a prerequisite for a society’s prosperity.”⁵ In addition, because three-fourths of the poor in the developing world still live in rural areas, and most of these are so-called “smallholder farmers,” growth in the agricultural sector is thought to be the most effective way to reduce poverty.¹⁰

Although often overlooked or even demonized, meat, milk, eggs and other animal products, including fish and other seafoods, play an important role in achieving food security. First, meat in the diet, if consumed regularly and in appropriate amounts (23 to 33 ounces per week, or 3.3 to 4.7 ounces per day), promotes a “healthy” lifestyle because meat, and especially red meat, contains high levels of digestible and readily absorbable iron, an excellent source of zinc, and the only dietary source of vitamin B12 which, along with folate, is a critical nutrient in 1-carbon metabolism.^11-13 Regular consumption of meats, poultry and eggs, in appropriate amounts, is acknowledged as part of a healthy diet by dietary guidelines in both the U.S. and Europe.^13-14

Importantly, many of these nutrients are deficient in a large portion of the world’s population.^15-17 In addition, meat is a rich source of high-quality protein that provides a balanced mixture of essential amino acids to support optimal growth and development of children, maintenance of muscle mass in adults and prevention of sarcopenia in the elderly.^18-20

Because animal products are widely recognized as high-quality foods, global demand is almost certain to continue to increase dramatically.^21,22 The drivers of the increased demand for animal products include not only population growth but also increased affluence, especially in the developing world, where much of the increase in population will occur.³

Livestock & Agricultural Sustainability

Livestock also are critical to agricultural sustainability, especially for smallholders, who comprise most of the world’s farmers.^17,21,22 Farm animals contribute not only a source of high-quality food that improves nutritional status but also provide additional resources such as manure for fertilizer, on-farm power and other by-products, and, in addition, provide economic diversification and risk distribution.¹¹ Moreover, increased efficiencies in the past several decades through genetic selection and improved management technologies have saved a large amount of resources, including water and land, and have substantially reduced the carbon footprint of animal production.¹¹

Additionally, ruminants such as buffalo, cattle, goats and sheep, efficiently convert the forages from grasslands into high-quality animal products, and grazing also can promote the health and biodiversity of grasslands if managed appropriately.^23-25 This is important because grassland pastures cover more than 25 percent of the earth’s land surface and, despite being home to nearlya billion people, comprise primarily marginally or non-arable land.^26,27

However, sustainable farm animal production will also require a more complete understanding of their impact on the environment. For example, a report by the Food and Agriculture Organization of the United Nations estimated that livestock, and especially ruminants, contribute as much as 18 percent of greenhouse gas emissions,²⁸ but other reporthave suggested this is a gross overestimate and the actual value may be as low as 3 percent.²⁹ Regardless, as farm animal production continues to increase, we need to be concerned with not only greenhouse gases but also the impact of farm animals on soil, water and biodiversity.^28-30

We also need to better understand how animal products in the diet might play a role in the global increase or decrease in noncommunicable diseases such as type 2 diabetes, obesity and cardiovascular disease, because these noncommunicable diseases are now responsible for more deaths worldwide than all other causes, including communicable diseases.^31,32 In this regard, reports from the National Research Council and the Office of Disease Prevention argue strongly for renewed focus, including additional research, on these controversial and critical issues.^22,33

Solving the problems and overcoming the obstacles to sustainable food security, although daunting, are not options, because food security is critical not only to human health but also to national security and global stability.³⁴ Feeding the world’s rapidly expanding population can therefore rightly be viewed as the main global challenge of the 21st century. Animals and Animal and Veterinary Scientists will play an important role in meeting this challenge.

Livestock as Models in Pregnancy Research

As mentioned, livestock have long been used as models to address problems of pregnancy,including infertility, poor fetal growth and development, and premature birth. For example, our research group in the Center for Nutrition and Pregnancy at NDSU has examined the role of macro-nutrients (for example, energy, protein) and micro-nutrients (for example, vitamins, minerals, one-carbon metabolites) in the maternal diet on pregnancy outcomes (fetal growth and development, birth weight, postnatal survival and development, among others) in sheep and cattle.^35,36 We also have examined the role of paternal diet prior to breeding on pregnancy outcomes.³⁷

These studies have yielded several important insights, including that:

1. The maternal diet, even before mating or very early in pregnancy, has profound effects on pregnancy outcomes.
2. The effects of poor maternal diet can be overcome, at least partly, by precision supplementation. That is, if one knows what is deficient in the maternal diet, supplementing those ingredients can overcome some of the negative effects on pregnancy outcomes.
3. The paternal diet before breeding, even during the father’s infancy, also can affect pregnancy outcomes.
4. Poor pregnancy outcomes, usually reflected by low birth weight, for example due to poor maternal or paternal diet or to premature birth, often have negative consequences for the offspring not only during the immediate postnatal period, but throughout the offspring’s life. Such negative consequences include poor survival, poor growth and body composition, and a two- to 10-fold increase in the risk of developing chronic health problems including obesity, diabetes, cardiovascular disease, cognitive and behavioral problems, during childhood and as adults.
5. These studies in livestock likely also apply to humans, and of course animal models are important as one cannot ethically study the effects of a low-calorie diet during human pregnancy.

As already mentioned, livestock provide humans with an excellent source of nutrient-dense foods that contains a balanced mixture of essential amino acids, as well as high levels of digestible and readily absorbable iron, zinc, vitamin B12 and folate. All of these nutrients are thought to be essential for fetal and postnatal growth and development, and their absence contributes to negative outcomes that impact the lifelong health and productivity of children, including poor growth and body composition, as well as poor development of the neural, immune, endocrine, reproductive and cardiovascular systems.

However, despite the fact there are very detailed dietary guidelines for animals during pregnancy—including dog and cats, horses, swine, small ruminants (sheep and goats), cattle and even nonhuman primates^38—we have few details about dietary needs, and how they change during pregnancy and lactation, in women. For example, the current Dietary Guidelines for Americans, which is the U.S. government’s official dietary guide, has recommendations only for intake of total calories and food groups (for example, vegetables and fruits, grains, dairy, protein foods, vitamins and minerals), and weight gain during pregnancy and lactation.¹³

This has always seemed an absurd situation to me, and one I believe must be corrected before we begin projecting what we think we know about essential nutrients and healthy diets for animals to pregnant and lactating women.

Livestock, and especially ruminants, will be essential to agricultural sustainability, as well as being key to food security in humans. Livestock also are important research models as we strive to improve our understanding of how various factors, such as maternal and paternal nutrition, affect pregnancy outcomes.

I would like to acknowledge the many mentors, colleagues and students with whom I have been fortunate to work during my research career. I will not include the long list as they know who they are. Their contributions have been both invaluable and generous, and for that I will be forever indebted. I also want to acknowledge the many funders of my research program, including the North Dakota Agricultural Experiment Station, the North Dakota State Board of Agricultural Research and Education, the U.S. National Institutes of Health, the U.S. National Science Foundation, the U.S. Department of Agriculture, and Purina Animal Health.

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