Abaye A O, Allen V G, Fontenot J P
Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0404.
J Anim Sci. 1994 Apr;72(4):1013-22. doi: 10.2527/1994.7241013x.
Cattle and sheep grazed together and separately from April to October during 3 yr. Initial forage composition was 29% Kentucky bluegrass (Poa pratensis L.), 11% white clover (Trifolium repens L.), and 60% weeds. There were six Angus cow-calf pairs or six ewes (1/2 Dorset x 1/4 Finn x 1/4 Rambouillet) with 11 lambs per each of three pasture replications for single animal species. Six cow-calf pairs plus six ewes and 11 lambs grazed in each of three replications of the mixed animal species treatment. There were approximately one cow and calf or five ewes with lambs per .44 ha. Lambs were weaned at 41 kg or by September 1. Calves were weaned approximately October 10. Lamb daily gain (.23 kg/d), total gain (23 kg), and weaning weights (43 kg) were greater (P < .01) and target weaning weights were reached 14 d earlier in the grazing season when both animal species grazed together than when lambs were in pastures with sheep alone (.18 kg/d, 19 and 38 kg, respectively). Calf gains were not influenced by treatment. Grazing pressure increased throughout the grazing season for cattle alone, peaked in midsummer, and then decreased by autumn for sheep alone, whereas grazing pressure initially increased then remained relatively constant with mixed-species grazing. Forage quality in pastures where sheep grazed alone was lower (P < .05) than in pastures where cattle grazed alone until lambs were weaned in late summer, whereas forage quality with mixed-species grazing was generally intermediate. Mixed grazing resulted in earlier weaning and increased lamb performance and BW of ewes, but not in increased animal production per hectare.
在3年的时间里，牛和羊于4月至10月期间一起或分开放牧。初始牧草组成包括29%的草地早熟禾（Poa pratensis L.）、11%的白三叶草（Trifolium repens L.）和60%的杂草。对于单一动物种类，在三个牧场重复中，每组有6对安格斯母牛-犊牛或6只母羊（1/2多塞特×1/4芬兰×1/4兰布列）以及11只羔羊。在混合动物种类处理的三个重复中，每组有6对母牛-犊牛加上6只母羊和11只羔羊。每0.44公顷大约有1头母牛和犊牛或5只带羔羊的母羊。羔羊在体重达到41千克或9月1日前断奶。犊牛大约在10月10日断奶。当两种动物一起放牧时，羔羊的日增重（0.23千克/天）、总增重（23千克）和断奶体重（43千克）更高（P < 0.01），并且在放牧季节比羔羊单独在羊群牧场时提前14天达到目标断奶体重（分别为0.18千克/天、19千克和38千克）。犊牛的增重不受处理影响。单独放牧的牛在整个放牧季节放牧压力增加，在仲夏达到峰值，然后秋季单独放牧的羊放牧压力下降，而混合放牧时放牧压力最初增加然后保持相对稳定。直到夏末羔羊断奶前，单独放牧母羊的牧场牧草质量低于单独放牧牛的牧场（P < 0.05），而混合放牧时的牧草质量通常处于中间水平。混合放牧导致羔羊更早断奶，提高了羔羊性能和母羊体重，但每公顷动物产量并未增加。
