农牧交错带人工草地放牧对奶牛生产性能的影响

研究不同放牧制度和强度对在“多年生禾草+紫花苜蓿(Medicago sativa)”人工草地上放牧奶牛的采食量、产奶量、乳成分及体重和体况分的影响。结果表明:轮牧制奶牛的采食量低于连续放牧制,中度放牧低于轻度放牧。轻度轮牧有较高的体增重和较小的体况分损失,连续放牧则相反。轮牧制奶牛的产奶量显著高于连续放牧制,中牧高于轻牧。不同放牧处理对乳成分的影响不显著,轻度轮牧的乳脂率低于中度轮牧和连续放牧,轻度轮牧的乳蛋白最高,乳糖和乳干物质含量则无显著变化。

Herbage Intake and Milk Performance of Dairy Cows Under Different Grazing Systems and Intensities in Agro-pastoral Transitional Zone of North China

A two-year study was conducted from 2004 to 2005 at China Agriculture University-based Guyuan Grassland Research Station,Hebei Province,to determine the effects of grazing system(continuous grazing,CG;and rotational grazing,RG) and grazing intensities(light,2.6 cows/hm2;moderate, 3.8 cows/hm2) on the herbage intake,milk yield,milk composition,live-weight and body condition of dairy cows grazing in mixed pasture of alfalfa-grass.The aim of the research was to obtain optimal management strategies for grazing dairy cows and pasture utilization in the region.The herbage intake of MCG cows was higher than that of MRG and LRG cows,but there was no significant difference between light and moderate grazing intensities.The LRG cows have the highest average daily gain and lowest body condition score loose.The total milk yields of MRG cows during the experimental period were significantly higher than that of LRG and MCG cows,and there were no significant differences among the three grazing treatments in milk composition,though LRG cows boast the lowest milk fat and higher milk protein content.