ARS/SCA: Supplementation of Cattle Grazing Endophyte-Infected Fescue

In each of 3 years, growing beef steers (n = 120/year) will graze on 20 fescue pastures at the C. Oran Little Research Center for approximately 112 days each year (April through July). Half of the cattle will graze on endophyte-infected (E+) pastures, and half on endophyte-free (E-) pastures. Within each fescue type, supplementation treatments will be administered which will include a control, with no protein or energy supplementation and combination of supplementation treatments to allow us to evaluate unique responses to lipid supplementation. Steers will be weighed at 28-d intervals, and biological samples (e.g. serum, subcutaneous fat biopsies) will be collected. In the final year of the study, a digestion experiment will be conducted. E(+) and E(-) hay will each be harvested and offered to steers in confinement with and without (negative control) supplements, as determined from the grazing studies. In this study, ruminally cannulated steers will be used. After steers have been adapted to their dietary treatments, we will measure voluntary forage intake, collect total fecal output for measurement of dry matter and fiber digestion, assess liquid and particulate passage rates, and ruminal fermentation characteristics.