Location: Livestock, Forage and Pasture Management Research Unit
2024 Annual Report
Objectives
The vision of this research is to increase the ecological and economic sustainability of forage based livestock production systems associated with the Southern Plains mixed grass prairie. Our strategy is to minimize environmental impacts and increase the efficiency of plant and animal resources while addressing the production and conservation goals for mixed grass prairie. Over the next 5 years, we will focus on these following objectives:
Objective 1: Improve native and introduced warm-season grass establishment and resilience to biotic and abiotic stressors.
Subobjective 1A: Evaluate 21 germplasm lines of little bluestem for establishment and adaptation at 3 sites.
Subobjective 1B: Select and breed Sudan grass with reduced ability to accumulate excess nitrate from the soil with a goal of releasing a new cultivar for use in the southern Great Plains.
Objective 2: Evaluate the potential for using patch-burning and weather assessment tools on rangelands to improve the productivity of stocker cattle, while enhancing other ecological services.
Subobjective 2A: Evaluate the potential for using patch-burning on rangelands to improve the productivity of stocker cattle while enhancing other ecological services.
Subobjective 2B: Contribute and utilize weather and climate tool applications through the Long-term Agroecosystem Research (LTAR) Climate Group for national and regional LTAR agricultural and natural resource modeling programs in grazing management, ecosystem monitoring and remote sensing, soil productivity, hydrology and erosion and evaluate, develop and implement landscape-scale applications for weather and climate related rangeland planning and management needs.
Objective 3: Determine the effects of weather, timing, and the amount of nitrogen (N) fertilization applied to forage grasses either through inorganic or organic N sources and their effect on ecological services.
Subobjective 3A: Determine the effects of the amount and timing of N fertilizer application on dormant season harvested switchgrass biomass production and changes in soil organic carbon stocks.
Subobjective 3B: Determine the utility value of underseeding red clover as an N fixer for winter-wheat pasture production to replace inorganic N from fertilizer.
Objective 4: Determine genetic, annual and seasonal effects on methane emission by grazing stocker cattle.
Subobjective 4A: Evaluation of new technologies in indirect calorimetry for grazing beef cattle.
Subobjective 4B: Gas flux by calves from dams identified as either high or low methane emitters.
Approach
The research described herein provides essential knowledge to enhance the production and conservation goals for Southern Plains agroecosystems. The Southern Plains mixed-grass prairie is one of the United States' most important crop and livestock-producing regions that supports many rural communities and provides habitat for a host of plants and animals. The region’s agricultural enterprises are challenged with uncertainties in profitability, reliance on unsustainable land use practices, and an ever-increasing concern for the environment. Specifically, this project will 1) improve native and introduced warm-season grass establishment and resilience to biotic and abiotic stressors, 2) evaluate the potential for using patch-burning and weather assessment tools on rangelands to improve the productivity of stocker cattle, while enhancing other ecosystem services, 3) determine the effects of weather, timing, and the amount of nitrogen fertilization when applied to cool-season annual or warm-season perennial forage grasses either through inorganic or organic nitrogen sources and their effect on ecological services, and 4) determine genetic, seasonal and annual effects on methane emission by grazing stocker cattle. Experiments will concentrate on breeding and selecting new perennial forages and the effects of livestock grazing, prescribed fire, and soil disturbances on vegetation composition, diversity, production, and vegetation heterogeneity and animal body weight (BW) gains. Coordinated experimentation will leverage interdisciplinary work of 4 scientists to address integration of forage-livestock systems through new forages, use of patch burning and livestock grazing management to support sustainable and economically viable agricultural enterprises.
Progress Report
This is the final report for research activities of the Objectives and Sub-objectives of the project 3070-21630-012-00D which was initiated in 2019, terminated in November 2023, and was replaced by 3070-21500-001-00D. No new experiments were initiated during the two-month timeframe of this report. All accomplishments and outreach activities are reported in the annual progress reports of the earlier project. Substantial results were realized within the Sub-objectives of the project over the five-year life of the project.
Sub-objective 1A: Evaluate twenty-one germplasm lines of little bluestem for establishment and adaptation at three sites, ARS researchers at Woodward, Oklahoma, showed that recurrent selection for germination at low water potential improved the likelihood of establishing little bluestem in the filed the research resulted in the release of two new little bluestem varieties that are now available to producers for use in native grass seed mixes.
Sub-objective 1B: Select and breed Sudan grass with reduced ability to accumulate excess nitrate from the soil with a goal of releasing a new cultivar for use in the southern Great Plain, ARS researchers at Woodward, Oklahoma, found that genetic variance composed most of the phenotypic variance in stem and leaf tissue and concluded that sufficient genetic variance exists for developing male sterile sorghum inbred lines having leaf nitrate concentrations below the potentially lethal toxicity threshold.
Sub-objective 2A: Evaluate the potential for using patch-burning on rangelands to improve the productivity of stocker cattle while enhancing other ecological services, ARS researchers at Woodward, Oklahoma, completed most of the pasture burns on schedule, with exceptions due to burn bans, and grazed the pastures each year. Preliminary analysis showed that cattle performance was not different between pastures burned under a patch-burn scheme, where a quarter of the pasture is burned each year in an annual rotation, and under a conventional broadcast burn treatment, where the entire pasture is burned every four years.
Sub-objective 2B: Contribute and utilize weather and climate tool applications through the Long-term Agroecosystem Research (LTAR) Climate Group for national and regional LTAR agricultural and natural resource modeling programs in grazing management, ecosystem monitoring and remote sensing, soil productivity, hydrology and erosion and evaluate, develop and implement landscape-scale applications for weather and climate related rangeland planning and management needs, ARS researchers in Woodward, Oklahoma, and Burns, Oregon, found a greater influence of late-winter and spring precipitation than that of models developed several decades ago where crop-year (September-June) precipitation provided more accurate herbage biomass estimates.
Sub-objective 3A: Determine the effects of the amount and timing of nitrogen fertilizer application on dormant season harvested switchgrass biomass production and changes in soil organic carbon stocks, ARS researchers in Woodward, Oklahoma, have completed initial soil sampling, establishment and initial fertility treatments of all the experimental plots, harvests, and some of the post-treatment soil samples. This study will be continued in the new project.
Sub-objective 4A: Evaluation of new technologies in indirect calorimetry for grazing beef cattle, ARS researchers at Woodward, Oklahoma, have completed all data collection for this study and have shown that automated head chamber systems can be used to provide useful estimates of energy intake by grazing beef cattle.
Sub-objective 4B: Gas flux by calves from dams identified as either high or low methane emitters, had a delayed start due to COVID-19 and ARS researchers at Woodward, Oklahoma, have collected gas flux data from dams and their calves for about half the number of pairs needed to estimate of how well methane emissions by the dam predicts methane emissions by the calves. This study will be continued in the new project.
Accomplishments
1. Utilizing gas flux from automated head chamber systems to estimate dietary energy values for beef cattle fed a finishing diet. Measuring greenhouse gas emissions and energy metabolism of live animals in their native environment is extremely important when designing food production system that are environmentally friendly and sustainable. Automated head chamber systems can be included into feedlots for beef cattle research, allowing for estimation of gas flux, heat production, and calculated gas-adjusted dietary net-energy for maintenance and body weight gain. However, a comparison between the head chamber-derived values and performance and carcass derived values had not been conducted. ARS researchers in Woodward, Oklahoma, evaluated the agreement between these two methods of measuring energy utilization using different approaches for calculating energy metabolism with either live or carcass derived data. There was excellent agreement between live net-energy parameters estimated by gas emission and live measurements or carcass measurements. Measures of precision, accuracy, and agreement were lower for carcass than for live-derived values when compared to gas emission values, but carcass derived values were still very acceptable. These results suggest that researchers and seed stock producer can implement the head chamber systems to provide estimates of heat production, gas flux, and estimates of energy efficiency in free moving feedlot beef cattle-fed diets ranging without sacrificing the cattle.
Review Publications
Springer, T., Moffet, C. 2024. Assessment of Oklahoma phlox in the Gypsum Hills of northwestern Oklahoma and southern Kansas. Oklahoma Native Plant Record. 22:26-37.
Bates, J.D., Copeland, S.M., Hardegree, S.P., Moffet, C., Davies, K.W. 2024. Weather effects on herbaceous yields: Wyoming big sagebrush steppe, southeastern Oregon. Western North American Naturalist. 84(1):89-106. https://doi.org/10.3398/064.084.0108.
Schantz, M.C., Hardegree, S.P., Sheley, R.L., Abatzoglou, J., Hegewisch, K., Elias, E.H., James, J., Moffet, C. 2024. Forecasts for rangeland management applications in the western United States. Rangeland Ecology and Management. 94:207-214. https://doi.org/10.1016/j.rama.2024.03.008.
Proctor, J.A., Smith, J.K., Long, N.S., Gunter, S.A., Gouvêa, V.N., Beck, M.R. 2024. Utilizing gas flux from automated head chamber systems to estimate dietary energy values for beef cattle fed a finishing diet. Journal of Animal Science. 102. Article skae167. https://doi.org/10.1093/jas/skae167.
Beck, M.R., Thompson, L.R., Reuter, R.R., Gunter, S.A. 2024. Recommendations on visit duration and sample number requirements for an automated head chamber system. Journal of Animal Science. 102. Article skae 158. https://doi.org/10.1093/jas/skae158.