Facts for Digestion: The Negative Effects of an Animal-Heavy Diet

A jet plane streaks across a cerulean backdrop, expelling a stream of smoke as it goes. An SUV cruises along the road, leaving a quickly dissipating trail of carbon dioxide in its wake. A coal factory darkens the sky view, interrupting the blue patches with plumes of smog. These are the typical images which come to mind when one hears the word “pollution;” the transportation sector or the energy sector. Rarely does one think of docile and overfed cattle in their stalls, or chickens crammed together in small cages. Yet the reality of this image is what globally accounts for about 20% of pollution: animal agribusiness [1]. Here in the United States, raising animals and producing animal products is more harmful to the environment than all of the cars, trains, and planes, which account for 10% of worldwide energy-related emissions [2]. Meat, dairy, and eggs are so deeply embedded in our diets that it is not something we often stop and think about. Yet there is a plethora of information confirming that diets heavily composed of meat and other animal products are harmful.

Raising animals strains the environment not only because it contributes generously to greenhouse gas emissions, but because it additionally contaminates water sources and aquatic ecosystems, and requires a staggering amount of resources. The efforts of researchers to render the production process more efficient and the efforts of government to regulate it offer some hope, but a smaller-scale, consumer-based solution with more immediate effects is the reduction of animal product consumption, especially meat. In a world of rising temperatures and scarcity, the rapid enactment of any solution is urgent, especially when one considers the sheer number of farm animals being bred for our eventual enjoyment.

There are over 1.5 billion cows and 1 billion pigs in the world [3]. They excrete an astonishing 80 million metric tons of waste annually [3]. Livestock-related emissions from digestive processes and animal wastes account for 26% of total agricultural greenhouse gas emissions. How? While being transferred to waste lagoons, liquid and solid wastes undergo chemical reactions which release methane [1]. But the major culprits are processes which take place in the digestive tracts of ruminants such as cows, called enteric processes, which result in 70% of agricultural methane emissions [1]. This might seem less incredible upon learning that methane production in cows is roughly equivalent to food intake [1][A].

Hogs are even more detrimental to the environment. An animal unit [B] of beef cow results in 59.1 pounds of waste every day [5]. An animal unit of hogs results in 63.1 pounds of waste on a daily basis [5]. Although this outnumbers hogs, porcine waste contains nutrient levels typically seven times higher than cattle excretions [6]. Nutrients may have a benign connotation, but they can contaminate surrounding waters when they seep out of overflowing or inefficient waste lagoons. The nitrates and phosphorous not only taint drinking water, but create dead zones in aquatic ecosystems when the formation of algal blooms causes oxygen depletion in the water. Manure runoff occurs even after it is removed from the lagoons, because it is used unnecessarily copiously as fertilizer. It is, after all, best from a farmer’s point of view to not risk providing too few nutrients to the soil [6]. Furthermore, this runoff contains microorganisms that are capable of causing illness, such as diarrheal diseases, in humans [1, 3]. Due to the common practice of giving superfluous antibiotics to cattle, hogs, and poultry to ward off sickness, the runoff may also contain bacterial strains resistant to many drugs [1, 3].

Animal byproducts are not the only problem. The resource input necessary to produce them is absurdly high, especially when compared to the amount required for grains and vegetables. With clean water becoming an increasingly precious resource, 2500 gallons are estimated to go into the manufacture of a pound of beef [7]. Other estimates are even more astronomical: a recent Cornell study placed the number around 13 000 [8]. Compare this to the 60 gallons needed for a pound of potatoes, and the mere six for a head of lettuce. Grains are slightly more intensive[C]. Attentive readers might point out that chicken has presented few problems thus far[D]. Here comes the snag: a kilogram of chicken requires 3500 liters of water to produce. That still outstrips the 2000 liters for a kilogram of soybeans [3].

A diet of primarily grains and legumes would require less intensive production and go some way to alleviating world hunger. Why, then, do many of us believe in and live on diet based primarily on meat and other animal products instead? Meat is not technically vital to life, and consuming it infrequently is actually better for our health. Humans are animals, whether we like to admit it or not, and our own bodies produce saturated fat. Its continuous intake can lead to atherosclerosis and other kinds of heart disease. Other natural products of our bodies are beneficial: bodies with normal metabolic function can synthesize all of the necessary proteins from only eight out of the twenty amino acids [9]. All eight of these basic amino acids can be obtained from beans and corn. Yet slicing into a cut of pork or chicken or biting into a beef patty is an event that occurs at least once a day for most people. Perhaps it is due to the prevalent belief that it is natural for us to be meat-eaters. Perhaps it is because ‘meat tastes good’, which is not an objective or rational argument at all. But no matter what the contrary claims are, the truth is that our diets and agribusiness are in need of reform.

Some countries have recognized the urgency of this need and have responded with legislation, the goal of which is to reduce the amount of waste run-off which is greatly detrimental to human health and the environment. The Netherlands has imposed limits on the phosphorous content of manure and the methods of its application [11]. The European Union has enacted legislation enforcing a maximum number of manure-producing animals per hectare of land available for manure-spreading [11]. A non-legislative trend is the methane digestor. These recent inventions separate liquid and solid wastes and generate electricity from methane, but they are costly and most of the electricity powers the dairy farms themselves [12].

There are, of course, other options that could ameliorate this problem: scientists could conduct more research about how to obtain greater amounts of milk, eggs, and meat from individual animals; ground meat manufacturers could begin to partially substitute plant-derived proteins for meat in their products; innovations in genetic engineering might result in organisms that produce less waste [1, 4, 11]. All of these approaches, however, would take time and involve some degree of uncertainty. The most evident solution begins with the consumer at the grocery store and the restaurant, and in a global situation where everyone watches one another enviously, making good choices is almost a responsibility for the privileged.

A worrisome global trend of increasing meat and dairy consumption can be observed in developing countries as per capita income rises. This trend is at least partly in emulation of the industrial world’s practices: countries like us. And it is the personal habits of United States residents which are the most dangerous: as a nation, we consumed 122 kilograms of meat per capita in the year 2000, more than any other nation in the world [11]. That number had not decreased in 2005, despite exceeding the USDA’s highly lenient Food Pyramid guidelines, and it sets a terrible example for other nations [13]. It is clear that our choices concerning food have wide-reaching impact, and currently they are destructive to animals, destructive to ourselves, and destructive to the world we inhabit.

[A] To be fair, the cows themselves do not strictly produce the methane; microbes which live in their guts do. Methanogens produce methane by reducing carbon dioxide with hydrogen gathered in the gut. The longer a cow’s food takes to digest, the more methane the digestion process generates. [4] Nowadays, industrial farming completely ignores the natural grazing habits of cows and raises them on soybeans and corn, which digest more slowly [1].

[B] An animal unit is equivalent to one thousand pounds of that organism. One cow usually weighs around 1400 pounds, or 1.4 animal units. A hog typically weighs 200 to 300 pounds, or 0.2-0.3 animal units [5].

[C] Wheat requires 108 gallons of water per bushel, corn 168, rice 229, and soybeans 240 [7]. Nevertheless, 40% of total grain yields worldwide currently are destined to be animal feed, although direct consumption would be more efficient [3].

[D] For comparison, one animal unit (about 125 eight-pound chickens) of chicken means about 15 metric tons of annual waste [10].


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Niloufar Hafizi is a first-year economics major at the University of Chicago. Please join The Triple Helix Online on Facebook. Follow The Triple Helix Online on Twitter