青藏高原天然草场放牧牦牛体重和体成分变化动态

WEIGHT AND BODY COMPOSITION DYNAMIC CHANGES OF YAKS GRAZING ON NATUR E GRASSLAND IN QINGHAI-TIBETAN PLATEAU

用逐月称重法和季节屠宰实验获得青藏高原放牧牦牛的体重和体成分变化的季节性动态规律。结果表明,放牧牦牛在出生后第一个冷季的体重下降幅度远低于第二个冷季,牦牛在秋季每公斤增重的能量含量以及秋季日增重均高于夏季,而冬季每公斤减重的能量含量则远高于春季。牦牛在第二个暖季所积累的能量约有一半以上在第二个冷季被消耗。在夏季和秋季增重过程中,牦牛的增重成分中都以水分为主,在秋季增重中,尽管增重成分中仍以水为主,但蛋白和脂肪所占的比例有所增加,因此每公斤增重的能量积累也明显升高。牦牛在冬春季体重下降过程中所损失的能量主要靠体蛋白的分解,尤其在第二个冬季掉膘期,这一趋势更加明显。

Seasonal dynamic of live weight and retuned energy accumulation of gra zing yaks on nature grassland in Qinghai-Tibetan Plateau was studied by using t he method of monthly weighting and comparative slaughter experiment.The results showed that the scale of lie weight decrease of grazing yaks in the first cold s eason was much more lower than that in the second cold season.The daily gain and energy retention of per kilogram weight gain of yaks was much more higher in au tumn than in summer.Energy content of per kilogram weight loss of yaks was much more higher in winter than in spring.More than half of the total energy retenti on of yaks during the second warm season was consumed during the second cold sea son.The main content of weight gain of yaks in summer and autumn was water,espec ially in summer,but crude protein and fat content increased from summer to autum n,which caused a rapid increase of energy content of weight gain.Energy loss of yaks in winter and spring was mainly depended on the decomposition of body prote in,especially in the second winter.