Submitted to: Proceedings of the National Conference on Grazing Lands
Publication Type: Proceedings
Publication Acceptance Date: December 1, 2009
Publication Date: June 15, 2010
Citation: Phillips, W.A., Coleman, S.W., Riley, D.G., Chase, C.C. 2010. Grazing Stategy To Decrease Dietary Crude Protien Wastage In Stocker Calves Grazing Winter Wheat Pasture.. Proceedings of the National Conference on Grazing Lands. pg. 13-16. Interpretive Summary: The protein concentration of wheat forage exceeds the daily requirement of grazing stocker calves by 100%. By employing a strategy of limiting the amount of time spent on wheat pasture by 50% and feeding a pelletized low-protein, high-energy supplement when not grazing wheat pasture, the protein density of the total diet was decreased from 28% to 15%. Animal performance was not depressed, but the amount of nitrogen excreted in the urine and volatized into the atmosphere was reduced.
Technical Abstract: Annual cool-season grasses, primarily winter wheat, provide high quality forage for stocker calves during the fall, winter and spring grazing seasons for stocker enterprises in the southern Great Plains. The crude protein (CP) content of winter wheat pasture exceeds the stocker calf’s daily CP requirement by 100 to 125%. Because the CP in wheat pasture is very digestible, the majority of the excess CP is excreted in the urine as urea. Balancing energy and CP intake by limit-grazing wheat pasture and providing a high energy supplemental feed would dilute the total dietary CP concentration and decrease the amount of CP that is excess to the calf’s need. In each of three years, stocker calves grazed wheat pasture continuously (Control) or were limited to grazing wheat pasture half of the time (Limit-grazed). Calves in the Limit-grazed group were fed a supplemental feed containing 9% CP, 2.25% fat, and 19% fiber and had ad libitum access to hay when not on pasture. The goal was to meet 50% of the calf’s DM intake requirement from wheat. Calves had a body weight of 552 lbs at the beginning of the 120-d winter grazing season. Average daily gain during the winter was 1.54 lbs and was not different (P > 0.10) between grazing management treatments. We concluded that limit-grazing of winter wheat pasture and providing supplement feed and hay can be used to reduce the amount of wheat forage consumed and N excreted in the urine without decreasing animal performance.