Location: Range and Livestock Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Develop management strategies to improve rangeland cattle production and ecological stability in the northern Great Plains through effective use of rangeland forage resources, precision supplementation, and livestock with greater adaptability to climatic, physiological, and nutritional stress. Sub-objective 1.1 Determine effects of dormant rangeland forage utilization on heifer development, plant productivity, and species composition. Sub-objective 1.2 Develop nutritional management for post-weaning heifer development to complement annual and weather-driven fluctuations in forage availability and quality. Sub-objective 1.3 Estimate effects of vegetation, climate, and environmental variables on cattle growth. Sub-objective 1.4 Develop mineral supplement and water amendment strategies to ameliorate weather-induced changes in naturally occurring rangeland stock water quality. Sub-objective 1.5 Develop a molecular barcode system for northern mixed-grass prairie plant species that will enable future description of plants consumed by livestock on rangelands. Objective 2: Develop management strategies integrating grazing, fire, and chemical practices to restore rangelands degraded by weeds and prevent weed invasions in the northern Great Plains. Sub-objective 2.1 Develop fire and herbicide treatment combinations to reduce annual brome abundance in rangelands. Sub-objective 2.2 Develop effective practices to rehabilitate rangeland riverine sites that have been mechanically and chemically treated to eradicate Russian olive. Sub-objective 2.3 Identify and develop effective reclamation strategies for converting coal mining lands back to livestock grazing lands. Sub-objective 2.4 Determine physiological traits allowing perennial seedlings to use dormancy to survive unfavorable environmental conditions. Objective 3: Develop adaptive strategies for managing the interacting effects of livestock grazing, fire, and climatic variation on northern Great Plains rangelands to increase the stability of livestock production while maintaining ecosystem health. Sub-objective 3.1 Quantify grazing season and intensity effects on plant community composition and productivity. Sub-objective 3.2 Quantify interacting effects of climate with defoliation timing and intensity on rangeland stability. Sub-objective 3.3 Determine rangeland community response to autumn defoliation intensity. Sub-objective 3.4 Determine post-fire weather effects on plant community response to summer fire. Sub-objective 3.5 Determine the effect of mycorrhizal fungi and different levels of simulated grazing on plant community composition and measures of soil health. Sub-objective 3.6 Determine plant and soil community response to fire return interval and seasonality.
1b. Approach (from AD-416):
Sustainability of rangeland production hinges on the stability of plant communities because changes in species composition, forage production, and forage quality fundamentally affect the animal community. The primary forces of change in rangelands are weather, grazing, alien plants, and fire. This project is designed to improve ecological sustainability and rangeland production by addressing opportunities for increased efficiency of livestock nutrient conversion, mechanisms affecting restoration success, and interacting effects of disturbances with weather and climate. We propose improved efficiency of nutrient conversion from dormant rangeland forages is among the most viable options for increasing animal production and minimizing effects on plant communities. We will address this proposition through a series of experiments evaluating plant and animal responses to dormant-season utilization and supplementation strategies. Rangeland restoration methods will be evaluated for direct weed control and mechanisms controlling successful establishment of desirable species. Water manipulations will be included in multiple experiments to determine weather and long-term climate effects because precipitation is the primary controlling factor for plant productivity and community composition. Experiments will be integrated across objectives to determine interacting effects of precipitation, grazing, weeds, and fire on soil and plant communities (production, species composition, diversity, propagation, survival) and cattle (weight gain, reproductive performance, diet quality, diet selection). Understanding the mechanisms that control rangeland stability and animal responses to alterations in plant communities will assist land managers and livestock producers in improving rangeland integrity and efficiency of livestock production. Results will also provide scientists greater understanding of the complex interacting forces on rangelands.
3. Progress Report:
Season and frequency of fire treatments were applied to begin second cycle, vegetation measurements were taken and soil microbial DNA and RNA, and grass axillary bud dynamics data were collected. Long-term livestock exclusion data were collected. Conducted preliminary experiment evaluating heifer performance following winter grazing supplementation with methionine and propionate. Grazing intensity x season experimental plots were fenced and grazing was initiated. Soil was cored to provide pretreatment data on soil properties for grazing intensity x season experiment. Mowing, fungicide, and herbicide treatments were applied for 4th yr. Data for climate effects on cattle growth were compiled. Data for identifying effective mine reclamation strategies was compiled. Data for identifying factors regulating shrub establishment on mine lands was analyzed.
1. Effect of weather on growth of beef cattle in the Northern Great Plains. Weather and climate are known to affect forage quantity and quality and animal stress, yet predictions of climate effects on livestock production are hindered by limited analyses comparing long-term climate and cattle production data. ARS researchers at Miles City, MT reported relationships between weather and calf weaning weight from 76-year records. Calves grew faster with long, cool growing seasons. Precipitation during late gestation and temperature during the first two weeks of summer were negatively related to calf growth. This work facilitates forecasting of climate effects on beef production and has led to collaborative research examining weather relationships with cow and steer performance with ARS researchers in Cheyenne, WY and Mandan, ND.
Reeves, J.L., Derner, J.D., Sanderson, M.A., Petersen, M.K., Vermeire, L.T., Hendrickson, J.R., Kronberg, S.L. 2013. Seasonal temperature and precipitation effects on cow-calf production in northern mixed-grass prairie. Livestock Science. 155:355-363.