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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Publications at this Location » Publication #354725
Research Project: Improved Practices to Conserve Air Quality, Maintain Animal Productivity, and Enhance Use of Manure and Soil Nutrients of Cattle Production Systems for the Southern Great Plains

Location: Livestock Nutrient Management Research

Title: Enteric nitrous oxide emissions from beef cattle

Author
item Parker, David
item Meyer, Beverly
item JENNINGS, TRACY - Texas A&M Agrilife
item JENNINGS, JENNY - Texas A&M Agrilife
item DOUGHERTY, HOLLAND - Texas A&M Agrilife
item COLE, ANDY - Retired ARS Employee
item CASEY, KEN - Texas A&M Agrilife

Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2018
Publication Date: 11/24/2018
Citation: Parker, D.B., Meyer, B.E., Jennings, T., Jennings, J., Dougherty, H., Cole, A.N., Casey, K. 2018. Enteric nitrous oxide emissions from beef cattle. Professional Animal Scientist. 34(6):594-607. https://doi.org/10.15232/pas.2018-01769.
DOI: https://doi.org/10.15232/pas.2018-01769

Interpretive Summary: Greenhouse gases such as nitrous oxide, methane, and carbon dioxide have been linked to climate change and global warming. During the digestion process, cattle generate a large amount of gas in the stomach, which is later belched through the mouth. The belched gas is composed primarily of methane and carbon dioxide. However, little is known about how much nitrous oxide is emitted. Scientists from USDA-ARS (Bushland, Texas) and Texas A and M AgriLife Research (Amarillo, Texas) conducted laboratory and live animal experiments to quantify nitrous oxide emissions from beef cattle belches. Nitrous oxide emissions from cattle belching were considerably lower than original estimates. Nitrous oxide emissions were directly related to the amount of nitrate in the feed. The global warming potential from belched nitrous oxide was much smaller than from belched methane, and also much smaller than nitrous oxide emitted from manure. Therefore, efforts to reduce greenhouse gases from cattle should focus on reducing belched methane.

Technical Abstract: Nitrous oxide (N2O) is a greenhouse gas (GHG) with a higher global warming potential than carbon dioxide (CO2) or methane (CH4). The objectives of this research were to quantify enteric N2O emissions from beef cattle and determine effects of dietary nitrate (NO3) concentrations. Experiments consisted of one in vitro (IV) incubation trial and two live animal (LA) trials. During the IV trial, gas was collected from four hay-based and five corn-based diets. During the LA trials, emissions were monitored from steers in respiration chambers. In LA trial 1, five measurements of 256 to 720 min were conducted on a single steer within a 48 h period. In LA trial 2, measurements were conducted on four steers in the absence of manure. Highest IV N2O production was from diets containing added NO3 or alfalfa. Enteric N2O increased with dietary NO3 concentrations (r2=0.99), with little correlation to dietary CP (r2=0.17). Added NO3 decreased CH4 emissions. Mean N2O emission rates from the LA trials were 6.93 mg/kg DMI in trial 1 and 2.20 mg/kg DMI in trial 2. Mean enteric N2O emissions accounted for 0.35 percent (LA trial 1) and 0.12 percent (LA trial 2) of CO2 equivalents. Enteric N2O emission rates were 6 to 40 times lower than earlier publications. Enteric N2O emission rates were also 58 to 108 times lower than emissions from manure, indicating that efforts to reduce GHG emissions from beef cattle should focus on enteric CH4 and manure N2O as opposed to enteric N2O.