Location: Forage and Livestock Production Unit
Title: Grazing strategy to decrease crude protein wastage in stocker calves grazing winter wheat pasture Authors
Submitted to: Proceedings of the National Conference on Grazing Lands
Publication Type: Abstract Only
Publication Acceptance Date: October 16, 2009
Publication Date: December 15, 2009
Citation: Phillips, W.A., Coleman, S.W., Riley, D.G., Chase, C.C. 2009. Grazing strategy to decrease crude protein wastage in stocker calves grazing winter wheat pasture. Proceedings of the National Conference on Grazing Lands. pg. 13. Interpretive Summary: abstract only.
Technical Abstract: Annual cool-season grasses, primarily winter wheat, provide high quality forage for stocker calves during the fall, winter and spring grazing season in the southern Great Plains. The crude protein content of winter wheat pasture exceeds the stocker calf’s daily crude protein requirement by 100 to 125%. Because the crude protein in wheat pasture is very digestible, the majority of the excess crude protein is excreted in the urine as urea. If soils are dry and the ambient temperature warm, more than 50% of urinary N is lost through volatilization. Balancing energy and crude protein intake by limit-grazing wheat pasture and providing a high energy supplemental feed would dilute the total dietary crude protein concentration and decrease the amount of crude protein that is excess to the calf’s need. The objective of this experiment was to determine stocker calf performance under this protein saving management strategy. Each year (N = 3), stocker calves grazed wheat pasture continuously (Control) or grazed wheat pasture half of the time (Limit-grazed) and were fed approximately 5 kg of a supplement containing 9% crude protein, 2.25% fat, and 19% fiber when not on pasture. The goal was to meet 50% of the calf’s DM intake from wheat and 50% from the supplement. Calves had a body weight of 251 kg (552 lbs) at the beginning of the 120-d winter grazing season. Average daily gain during the winter was 0.70 kg (1.54 lbs) and was not different (P > 0.10) between management treatments. Based on the rate of gain observed in this experiment, we concluded that limit-grazing of winter wheat pasture can be used to reduce the amount of wheat forage consumed. By providing a low-protein high-energy supplement to balance dietary content, wastage of dietary crude protein could be reduced.