There has been a lot of discussion about cattle and the impact the animals have on the environment the last few years. As the concept of global warming takes hold, livestock are increasingly being singled out for contributing to the greenhouse effect caused by increased levels of carbon dioxide, chlorofluorocarbons, and other pollutants.
Because cattle are ruminants, they eat plants like grasses that are difficult to digest, even with a four-chambered stomach. A microbe that resides in their stomachs, called methanogens, converts feed into a product that can be digested by the animal. This process produces methane gas which is exhaled by the animal, mainly via burps.
Although methane is a more potent greenhouse gas — about 20 times stronger than carbon dioxide (CO2) — there is over 200 times more CO2 in the atmosphere. Methane in the atmosphere will react with oxygen and eventually become transformed into carbon dioxide, making it a strong contributor to the greenhouse effect .
So it can’t be denied that cattle and other livestock do contribute some to the greenhouse effect, but according to the Environmental Protection Agency (EPA) in 2013, greenhouse gas emissions from agriculture accounted for approximately 9% of the total U.S. greenhouse gas emissions, and most of that 9 percent comes from soil management (crop farming). Nicolette Hahn Niman, author of Defending Beef: The Case for Sustainable Meat Production states that a Union of Concerned Scientists report concluded that about 2% of U.S. greenhouse gases can be linked directly to cattle, and good management would diminish it further.
As a longtime vegetarian and environmental lawyer, Niman stated in an article she wrote for the Wall Street Journal, “Actually, Raising Beef Is Good for the Planet, that she once bought into claims that cattle have an “outsize ecological footprint,” guzzling water, trampling plants and soils, and consuming grains that should be reserved for hungry humans. But now, she wrote,
“After more than a decade of living and working in the business—my husband, Bill, founded Niman Ranch but left the company in 2007, and we now have a grass-fed beef company—I’ve come to the opposite view. It isn’t just that the alarm over the environmental effects of beef are overstated. It’s that raising beef cattle, especially on grass, is an environmental gain for the planet.”
Niman states that “Most of the world’s beef cattle are raised on grass. Their pruning mouths stimulate vegetative growth as their trampling hoofs and digestive tracts foster seed germination and nutrient recycling. These beneficial disturbances, like those once caused by wild grazing herds, prevent the encroachment of woody shrubs and are necessary for the functioning of grassland ecosystems.” Now it appears domestic livestock are taking on the environmental role that was once delegated to buffalo.
In an USDA Ag Research magazine article, Dennis O’Brien, with the Agricultural Research Service information staff, reported on a project where researchers planted grasses on 37 acres of rolling, eroded land in Georgia. They allowed beef cattle to graze there to assess the effects on soil quality. The cattle grazed on costal bermudagrass initially and then tall fescue when the grass was in a dormant winter stage to extend the grazing season from five to 10 months. The research team varied the number of cattle per acre, and over 12 years they assessed how the soils responded to four different scenarios:
• moderate grazing (average of 23 steers for every 10 acres)
•intensive or heavy grazing (35 steers per 10 acres)
•no grazing and letting the grass grow
•no grazing but cutting the grass for hay
O’Brien reports, “Under each scenario they looked at the amount of soil compaction that occurred, the amounts of soil organic carbon and nitrogen found in the soils, and the amounts of surface plant residues, which help prevent erosion. They also looked at the effects on the soil of three different fertilizer treatments: inorganic fertilizer, organic broiler litter, and a mix of inorganic fertilizer and organic broiler litter.”
The team found that fertilizer type made little difference, but different grazing scenarios produced dramatically different effects. “Land that was grazed produced more grass than ungrazed land, and grazing led to the most carbon and nitrogen being sequestered in soil. Sequestering carbon and nitrogen in the soil has become a major goal for agriculture because it reduces greenhouse gas emissions by storing carbon to maintain a balanced carbon cycle.
The researchers found that whether grass was grazed moderately or intensely made little difference on sequestration rates. Their conclusion, published in the Soil Science Society of America Journal, demonstrated that “if growers manage cattle so that pastures are grazed moderately, they’re restoring soil quality and cutting greenhouse gases by keeping carbon in the soil as organic matter rather than releasing it into the atmosphere as carbon dioxide.”
Some have argued that the solution to reducing methane gas would be to cut back on the amount of meat and animal byproducts consumed, but as you can see by this study, cattle can actually contribute to a healthier environment. Cutting down livestock numbers is also not a viable solution to reduce the percentage of greenhouse gasses because living plants also exhale methane, and as stated above, are the largest contributor of methane gas in the agriculture sector. But when you consider that agriculture contributes a small percentage to the overall greenhouse gas emissions and cattle an even smaller percentage, it appears there are other more relevant areas to focus on if we are to make a significant reduction in greenhouse gas emissions. Transportation, electricity and emissions generated from industry make most of the greenhouse emissions that scientists say are contributing to global warming.
However, no matter how small the emissions are compared to other sectors, we as ranchers, need to mitigate any environmental damage that we can. According to the Food and Agriculture Organization of the United Nations (FAO) methane emission from beef cattle can be reduced by breeding for higher feed conversion efficiency, proper nutrition and animal husbandry. In Australia they have studied the use of nutritional supplements aimed at reducing greenhouse gas emissions in beef cattle.
In Canada, researchers say increasing the level of dietary fat by feeding a diet of crushed oilseeds (sunflower seed, canola seed or flaxseed) or dried corn distillers grain reduced the energy lost as methane by up to twenty percent. According to Agriculture and Agri-Food Canada (AAFC), feed additives, including plant extracts (condensed tannins, saponins, essential oils) and rumen modifiers (yeast, bacterial direct fed microbials, and enzymes) also look promising. In a recent study, they supplemented the cattle diet with commercial active dried yeast products including a product that improves fiber digestion in the rumen. This combination was found to reduce methane by six percent.
Stonyfield Farm, a Vermont-based yogurt manufacturer, since 2008 has been successfully experimenting with adding alfalfa and flaxseed to their diary cows’ diets as a way of reducing methane. Reports indicate that their feed program has reduced enteric emissions from the cows by as much as 18 percent, and an average of 12 percent.
Researchers have also found that garlic and cinnamon reduce methane production to some degree. Dr. Alexander Hristov, associate professor of diary science at Pennsylvania State University, has been looking at oregano as a methane reducer. In one trial, adding a pound of oregano to a cow’s daily feed reduced methane emissions by 40 percent and increased milk production by about 4 percent. Exactly how good the long-term improvement might be is still up in the air. In a second trial emission reductions shrank to 27 percent leaving room for further study.
Scientists and researchers in agriculture, worldwide, continue to work at finding solutions to reduce methane gas emissions in livestock. Most livestock producers we know are already utilizing good management strategies, which as scientists have already discovered, can help reduce methane gas emissions in cattle and lead to more carbon and nitrogen being sequestered in soil. As the greenhouse effect progresses we will undoubtedly be looking at other ways to reduce emissions in livestock production. After all, it is to cattle producers’ advantage to protect the environment, which is their (our) livelihood. Any form of agriculture requires good stewardship, and a workable plan to preserve the land/environment for future generations is a necessity. It is a monumental challenge on a global scale to find ways to feed a growing population while reducing emissions.
Note: On researching this topic, I found numerous percentage differences in the amount of damage livestock do to the environment in terms of methane gas, but I feel confident in the EPA’s numbers.
What is your opinion on the impact cattle have on greenhouse emissions? Please leave your comments below.