Impact of Beef Cattle on the Environment

Authors: Rotz, Clarence - Al

Submitted to: American Dairy Science Association Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/2/2023
Publication Date: 4/12/2023
Citation: Rotz, C.A. 2023. Impact of Beef Cattle on the Environment[abstract]. American Dairy Science Association Proceedings. p. 1.

Interpretive Summary: No Interpretive Summary is required for this Abstract Only. JLB.

Technical Abstract: Beef cattle production has several important impacts on the environment. Greenhouse gas (GHG) emissions is of major global importance. Other important regional impacts include nutrient losses, water consumption, and fossil energy use. Due to the many components in production systems and their interactions, a comprehensive life cycle assessment is needed to quantify and compare the impacts of production strategies. The life cycle annual GHG emission related to beef production and consumption in the U.S. is about 250 Tg or 3.7% of the total national GHG emission inventory. Of this total, about 80% is related to producing the cattle. Within cattle production, about 58% is from enteric emissions, 23% is in feed production and 7% is related to manure management. Greenhouse gas emissions from beef production in the U.S. are decreasing. Compared to 50 years ago, we now produce 20% more meat using about 15% fewer cattle. The GHG intensity in cattle production has dropped 34% from 32 to 21 kg CO2e/kg carcass weight produced, and the total GHG emission related to beef cattle production has decreased 21% from 324 to 255 Tg. One-hundred-year global warming potential (GWP100) factors are normally used to total the warming effect of different GHG compounds to CO2 equivalents. However, GWP100 factors do not properly represent the effects of methane, which is a short-lived gas that oxidizes in the atmosphere with a half-life of about 8 years. This has led to the development of a new relationship referred to as GWP*. Considering the change that has occurred over the past 50 years, using this model reduces the global warming impact of beef cattle by over 50% relative to use of current GWP100 factors. Various mitigation strategies are being considered to reduce emissions in cattle production. Those considered for feedlot finishing include more efficient feeding, enteric methane inhibitors, anaerobic digestion of manure, and removal of manure storage. Use of a combination of these practices may reduce feedlot finishing emissions by 50%. Over the cattle production cycle, feedlot finishing only contributes about 14% of the total life cycle emissions, so a 50% reduction in the feedlot phase provides only a small 3% reduction in the total emission of cattle production. Reductions in the cow calf phase would provide greater benefit, but mitigation in this phase, where cows are maintained on pasture and rangeland, is difficult. Carbon sequestration in pasture soils can be very beneficial in reducing GHG warming when this capture of carbon can be quantified. Another important environmental consideration is ammonia emission from manure. We estimate the total ammonia emission in beef cattle production in the U.S. is about 908 Gg of nitrogen, which is around 30% of the total emission in the U.S. This large contribution to U.S. inventory makes this an important need for mitigation. Non precipitation water use in cattle production is also important with about 6% of the total water consumption in the U.S. related to cattle production. Fossil energy use is always an important consideration for sustainability, but that used in cattle production is less than 1% of the total use in the U.S. Perhaps one of the more important considerations in the sustainability of beef, as well as all foods, is consumer waste where the estimated waste of 20% increases all metrics or measures of the sustainability of beef consumption by 25%.