Current research focus is on examining the productivity, profitability, and associated responsible biological mechanisms of 3 different season-of-calving production systems (i.e., mid winter (Feb.), early spring (April) and late spring (June)). Detailed studies are being conducted to elucidate nutritional profiles as they relate to both animal requirements and forage availability. Tactics are being developed for overcoming nutritional limitations imposed by these season of calving management strategies. Herbage, diet, & environmental variables are being monitored to evaluate the nutritional regimen under which the systems function and the interaction of the grazing animal with available rangeland resources. Trials are being conducted to aid in understanding animal response patterns to varying nutrient supplementation strategies. Additional research focuses on the relationships between grazing livestock in the control or spread of noxious weeds. Specific study objectives include: 1) evaluation of ruminal dynamics when exposed to various concentrations of noxious weeds, and 2) impact of secondary compounds or fermentation products on selection aversions in grazing livestock.