Final report for GW22-232
Project Information
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
Cooperators
- - Producer
- (Researcher)
Research
Materials and methods:
Project Site:
This study was be conducted at the United States Department of Agriculture Agricultural Research Service- Central Plains Experimental Range (CPER) approximately 12 km northeast of Nunn, Colorado, USA (40°50′N, 104°43’W), which is a Long-Term Agroecosystem Research (LTAR) site. Long-term mean annual precipitation is 340 mm, of which > 80% occurs during the growing season of April through September.
Objectives & Hypothesis:
The overall objective of this experiment was to evaluate the impact of animal origin on enteric CH4 emissions and animal performance. Two animal origins, and thus two sources of distinctly different genetics, were used in this trial on yearling stocker steers grazing a high productivity pasture in the shortgrass steppe rangeland ecosystem. For the cattle genetics steers were sourced from 1) the USDA Meat Animal Research Center (MARC) in Clay Center, originating from a tallgrass prairie ecosystem, where steers were genetically selected for high growth – weaning and yearling weights – and carcass quality, and 2) the Crow Valley Livestock Cooperative (CVLC) in Nunn, Colorado where steers were locally-adapted to the shortgrass steppe and genetically selected to match the animal to the environment that optimizes production efficiencies rather than production output. Yearling steers (British) were grazed in a 320-acre high productivity pasture (>1,000 kg/acre) with livestock gains previously demonstrated in this high productivity native pasture ecosystem (Reynolds et al. 2019).
This work was exploratory, as individual animal CH4 emissions from stocker cattle have not been quantified in this ecosystem, nor have genetic influences on enteric emissions been evaluated in extensive grazing lands. Prior efforts with yearling steers from these two providers have demonstrated an approximately 20% lower average daily gain with steers from MARC compared to local steers (Reynolds et al., in prep). Unclear, however, is whether individual animal enteric CH4 emissions differ with genetics and how to select for yearlings that will emit less CH4 per unit of gain. We hypothesized that steers that were locally adapted to the shortgrass steppe ecosystem would gain more and thus have a lower emissions intensity.
Research Design:
For this pilot observational study, 26 steers (MARC=7; CLVC=19; BW = 322 ± 39 kg) were grazed in a high-productivity shortgrass steppe ecosystem and voluntarily acclimated to one Greenfeed automated head chamber system (C-Lock Inc., Rapid City, SD) equipped with a CH4 sensor, for measuring greenhouse gas (GHG) emissions. Steers were sourced from two origins, 1) local, northeastern Colorado shortgrass steppe steers from the Crow Valley Livestock Cooperative, Inc. (CVLC), and 2) south-central Nebraska tallgrass prairie steers from the USDA Meat Animal Research Center (MARC). Of the 26 steers, 12 steers (BW = 305 ± 38 kg; 9 CVLC, 3 MARC) voluntarily acclimated to the GreenFeed. Daily, CH4 was measured with one GreenFeed (C-Lock, Inc., Rapid City, SD) from July to August. Data collection included individual daily CH4 production (g/hd/d), CH4 emissions intensity (EI; g CH4/kg body weight gain), and 28-day interval animal body weights (kg).
Outreach Design:
One producer-oriented field day was conducted in July 2022, in partnership with USDA-ARS and Colorado Cattlemen’s Association, where local producers of all ages and demographics were invited to the USDA-ARS CPER where they engaged and learned from researchers. During this field day, producers enhanced their knowledge of sustainability, rangeland management, and cooperative research by viewing the ongoing research being conducted in real-time and learning about the GreenFeed and its research capabilities.
Additional outreach and engagement that has occurred included the publishing of a blog regarding the research activities funded by this WSARE grant in September 2022 by AgNext. Research findings were also shared at the AgNext Industry Innovation Working Group meeting with industry stakeholders throughout the beef supply chain in December 2022, at the Society for Range Management Annual Meeting in February 2023, the AgNext Research Summit in June 2023, and at the WSARE Building Partnerships for Agricultural Sustainability Summit (BPASS) in December 2023.
Analysis Methods:
Data was analyzed using the ANOVA procedure in R© (R Core Team, 2023). Origin and initial body weight were included in the model as fixed effects. The experimental unit was animal (n=12). The independent variable of interest was origin (MARC vs. CVLC). Dependent variables of interest include average daily gain (ADG), daily CH4 emissions (g CH4/d), and emission intensity (g CH4/kg ADG).
The result of this study indicate that individual daily CH4 production ranged from 113 to 262 g CH4/day. Steers originating from the CVLV exhibited greater CH4 production (CVLC: 203 vs. MARC: 169 g CH4/day; P=0.04), but CVLC steers had a lower CH4 emissions intensity (238 vs. 419 g CH4/kg ADG; P=0.04). Steers originating from CVLC had a greater ADG than MARC steers (0.54 vs 0.18 kg/day; P=0.03). Therefore, the results of this study indicate that cattle origin alters CH4 emissions and animal performance in stocker steers grazing extensive semi-arid rangelands. In addition, we compared measured CH4 emissions with predicted emissions calculated using the Intergovernmental Panel on Climate Change tier 2 methodology; measured emissions were 31% greater than predicted for the local CVLC steers and 18% greater than steers from non-local MARC steers. 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. Further research should consider not only the environmental impact of cattle origin in a grazing system, but also the environmental impact of cattle that are backgrounded on a high forage diet and then moved back into a confined setting during the finishing period.
Research Outcomes
The result of this study indicate that daily CH4 production ranged from 153 to 238 g CH4/day. Steers originating from the CVLV exhibited greater CH4 production (P=0.044), but CVLC steers had a lower CH4 emissions intensity (g CH4/kg ADG; P=0.033). Steers originating from CVLC had a greater ADG than MARC steers (P=0.0064). Therefore, 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. Further research should consider not only the environmental impact of cattle origin in a grazing system, but also the environmental impact of cattle that are backgrounded on a high forage diet and then moved back into a confined setting during the finishing period.
Education and Outreach
Participation Summary:
One producer-oriented field day was conducted in July 2022, in partnership with USDA-ARS and Colorado Cattlemen’s Association, where local producers of all ages and demographics were invited to the USDA-ARS CPER where they engaged and learned from researchers. During this field day, producers enhanced their knowledge of sustainability, rangeland management, and cooperative research by viewing the ongoing research being conducted in real-time and learning about the GreenFeed and its research capabilities.
Additional outreach and engagement that has occurred included the publishing of a blog regarding the research activities funded by this WSARE grant in September 2022 by AgNext. Research findings were also shared at the AgNext Industry Innovation Working Group meeting with industry stakeholders throughout the beef supply chain in December 2022, at the Society for Range Management Annual Meeting in March 2023, the AgNext Research Summit in June 2023, and the WSARE BPASS conference in December 2023.