Impact of genetics and grazing management on enteric methane emissions and performance in stocker steers

View the project final report

Commodities

• Animals: bovine

Practices

• Animal Production: genetics, grazing management, rangeland/pasture management
• Education and Training: extension

In the United States, animal agriculture accounts for approximately 3.8% of greenhouse gas (GHG) emissions and enteric methane (CH₄) production accounts for approximately 30% of total CH₄ emissions (EPA, 2021). Current beef industry life-cycle assessments indicate that approximately 60-70% of the industry’s GHG emissions and 70-80% of the industry’s CH₄ emissions are from grazing systems, prompting a need for mitigation strategies focused in grazing environments (Rotz et al., 2019). However, GHG emissions, specifically enteric CH₄ emissions, are largely unknown from cattle grazing extensive semi-arid rangelands. Our research question is, “Do stocker steers originating from different regions exhibit differences in individual animal CH₄ emissions?”. The objective of this study was to evaluate the impact of cattle origin on CH₄ emissions and animal performance. Steers were sourced from 1) the Crow Valley Livestock Cooperative (CVLC) in Nunn, Colorado and 2) the USDA Meat Animal Research Center (MARC) in Clay Center, Nebraska. Cattle grazed the USDA-ARS Central Plains Experiment Range in Nunn, Colorado on a high productivity shortgrass steppe pasture from May to August. One GreenFeed automated head chamber system (C-Lock Inc., Rapid City, SD) was utilized to measure CH₄ emissions on 12 steers (BW = 305 ± 38 kg; 9 CVLC; 3 MARC). Steers were individually weighed at 28-day increments throughout the grazing season to calculate average daily gain (ADG). Statistical analysis was conducted in R^© with the fixed effect of origin. Daily CH₄ production ranged from 113 to 262 g CH₄/day. Steers originating from the CVLV exhibited greater CH₄ production (203 vs. 169 g CH₄/day; P=0.044), but CVLC steers had a lower CH₄ emissions intensity (238 vs. 419 g CH₄/kg ADG; P=0.033). Steers originating from CVLC had a greater ADG than MARC steers (0.54 vs 0.18 g/day; P=0.0064). Stakeholders were explicitly involved in all aspects of this research to assist with the dissemination of findings via a producer-oriented field day, which occurred in July 2022, a blog post, three industry-oriented presentations, and two agricultural professional presentations. The results of this study indicate that cattle origin alters CH₄ emissions and animal performance in stocker steers grazing extensive semi-arid rangelands. With further research, we expect genetic differences to influence individual animal enteric emissions and this outcome could be incorporated into selection efforts to mitigate CH₄ emissions.  

Research Objectives: 

• Determine how origin impacts enteric CH4 emissions and animal performance in stocker steers grazing in a shortgrass steppe ecosystem

Educational Objectives: 

• Producers report changes in knowledge, attitudes, skills, and/or awareness as a result of their participation in the educational programming resulting from data discovered from this project
• Improve collaboration between research institutions, government organizations, and producers