不同放牧强度对滩羊生产性能影响的研究

为寻找适宜宁夏盐池县草地的放牧强度,于2003年5-11月在该县四墩子试点设5个处理(0.45、0.60、1.75、1.05和1.50只/hm2)进行轮牧,轮牧周期为42 d,共放牧154 d。结果表明:1)滩羊采食量随放牧强度的加重而降低。同一放牧强度下,随放牧时间推移,采食量先逐渐增大而后下降。2)在试验期内,不同放牧强度下,滩羊体重随时间推移总体上都呈增加趋势。在10月2日之后体重开始出现分化。与放牧强度重的处理相比,放牧强度轻的处理日增重峰值较高,持续时间较长。3)滩羊个体增重与放牧强度之间存在着强的负相关;单位草地面积(1 hm2)增重与放牧强度之间呈强的正相关,初步可以确定在该类草地上放牧强度应在0.75只/hm2左右。4)随着放牧强度的加重,饲料报酬先增大后减小。在同一放牧强度下,饲料报酬随时间的推移先升高后降低。5)当放牧强度超过0.75只/hm2以后,滩羊出现了空怀、产羔率降低和推迟怀孕的现象。6)综合考虑各研究指标,该类草地放牧强度以不应超过0.75只/hm2为宜。

Studies on effects of different grazing intensity on productivity of Tan sheep

Five treatments(0.45,0.6,0.75,1.05,1.5 head/hm~2) and 3 plots under 42d-cycle rotational grazing system were designed to test the effects of different grazing intensity on Tan sheep productivity in Sidunzi,Yanchi county of NingXia,from May to November in 2003.The results showed that: 1) Feed intake of Tan sheep decreased as grazing intensity went up.Under the same grazing intensity,feed intake increased firstly,and then decreased as the time went by.2) The live weight of Tan sheep showed increasing tendency under different grazing intensity,but differentiated from October 2.Compared with those under higher grazing intensity,the sheep in light grazing intensity gained more live weight.3) There were negative correlation between live weight gain per sheep and grazing intensity and positive correlation between live weight gain per hectare and grazing intensity.4) With the increasing grazing intensity,feed conversion increased first,and then decreased.Under the same grazing intensity,feed conversion gave similar trend as grazing time prolonged.5) Under higher grazing intensity than 0.75 head/hm~2,the barren rate of Tan sheep increased,lambing percentage dropped and pregnancy postponed.6) As a result,the appropriate grazing intensity in this type rangeland could not exceed 0.75 head/hm~2.