According to a report by the UN’s Food and Agriculture Organization (FAO) published in 2013, the global cattle sector (both beef and dairy) accounts for about 61 percent of the livestock sector’s annual greenhouse gas (GHG) emissions, which overall represents about 15 percent of global emissions. Production of smaller ruminant animals, such as sheep and goats, add about 450 million metric tons of carbon dioxide (CO2) equivalent to the annual global total, bringing the ruminant share to about 66 percent. These emissions come primarily from enteric fermentation that occurs during feed digestion in the ruminant animal’s gastrointestinal system, and from emissions associated with producing and delivering feed to these animals.
Some climate activists have suggested the best solution to this problem is to simply mandate the end of production of ruminant animals around the world, but that approach ignores the nutritional impact of removing these foods from the human diet, which provide about one-third of all animal protein and about 17 percent of all calories consumed. The diets of hundreds of millions of people in the developing world are already deficient in animal proteins, which provide necessary amino acids and trace minerals to humans that are not available from a solely plant-based diet. Milk and dairy products also play a crucial role in diets, especially among young children.
Rather than continue to push a politically unpopular approach, since most people enjoy eating red meat--a May 2021 Ipsos poll found that 89 percent of Americans include meat in their diets--groups pushing an aggressive path toward reducing greenhouse gas emissions should work with agricultural organizations and researchers to find and adopt ways to reducing the emissions footprint of the livestock sector.
One key factor to keep in mind is that while the annual GHG footprint of beef produced from the average cow in the world is 300 kilograms of CO2 equivalent per kg of animal protein, that figure falls considerably when one looks at the footprint of beef cattle raised in developed countries such as the United States, because of superior genetics and better feeding practices. A Florida cattle rancher that I work with at the Farm Journal Foundation, Renee Strickland, also exports live animals such as cows, goats, and sheep to developing countries. In a recent conversation, she described exporting dairy cows to a farmer in Pakistan, who will replace his native breed cows with higher productivity U.S. cows, increasing his per cow daily milk yield by two-thirds. In 2020, the United States exported $290 million worth of live animals to developing countries other than Mexico, where animals were likely intended for direct slaughter rather than used for breeding purposes. The U.S. also exported $162 million worth of bovine semen to developing countries in that year.
In developed countries, farmers with ruminant animals can also reduce their operation’s GHG footprint by shifting their animals’ diets away from grain toward more use of forage and grazing, especially if that forage is grown through use of perennial grasses or cover cropping. Both of these practices help to sequester additional carbon in the soil, as does expanded use of rotational grazing practices. A recent study published in the Canadian Journal of Animal Science found that cattle with low forage to grain feed consumption produced 42 percent more methane than did animals fed a higher forage to grain ratio.
There has also been considerable research undertaken to find ways to reduce methane emissions from ruminants through use of feed additives. As described in the policy brief I co-authored with Dr. John Reilly in May 2021, one recent discovery has found that under experimental conditions, particular types of seaweed added in relatively small amounts to the livestock diet can almost completely eliminate methane emissions without negatively
affecting livestock digestion. Efforts to breed animals whose gastrointestinal systems digest feed more efficiently and thus emit less methane is also underway at various universities around the world including in Denmark, Australia, Israel, Finland, the United States, and the United Kingdom.
Pursuing a more offbeat approach, it was reported this month that scientists in Germany had been successful in training a small group of calves to defecate and urinate in a single location, which allows easier collection and neutralization of the ammonium contained in those waste products.
In order to tackle a problem of this magnitude, the U.S. government needs to invest more resources into these areas of research, and also to help research systems in developing countries to do more to improve the genetics and thus productivity of its ruminant livestock herds. As Dr. Frank Mitloehner, professor of animal science at the University of California-Davis has said, “it takes about 15 to 20 cows in India to produce the same amount of milk as one cow in the United States.” Even small improvements in productivity in a national herd of that size can have enormous implications for GHG emissions from livestock. Passage of the Build Back Better Act, which in the House version includes $7.75 billion to fund agricultural research into climate change issues, would be a massive step in the right direction for this effort
Farmers in particular and agriculture in general have to figure out a way to balance the need to mitigate climate change and produce enough food to feed a global population that is expected to approach 10 billion people by the year 2050, while making enough profit to stay in business.
