Studies On Effects On Productivity Of Tan Sheep Under Different Grazing Intensity

Studies on effects on productivity of Tan sheep under different grazing intensity were carried on Si Dunzi experimental units, Yan chi of NingXia from May to November in 2003. The aim of experiment was to find out a appropriate grazing intensity of this type range. Experiment design included five treatments (0. 450sheep/hm2, 0. 600sheep/hm2, 0. 750sheep/hm2, 1.050sheep/hmz and 1.500sheep/hm2). In order to utilize the range relatively uniform, each district was separated three little districts, and rotational grazed by sheep, the rotational cycle was 42 days, and total grazing time was!54 days.The results showed that: (1) Feed intake of Tan sheep decreased as the grazing intensity becomed heavier, it could be described as: Y=2.04-0. 54X (r=-0.92*). Under the same grazing intensity, feed intake increased at first, and then decreased as the time passed.(2) As the grazing intensity faecomed heavier, the eating time of Tan sheep increased while resting and idling time decreased; Feed intake per hundred mouths and daily intake reduced, intake velocity increased; The daily dezection times and drinking water were not distinct variation. The regressional equation between intake velocity and the feed intake per hundred mouths was: Y=81.85-l. 28X(r=-0. 95).(3) Acceptability of Tan sheep is relative. With the grazing intensity becomed heavier, grazing day increased in the identical rotational little district, and partial eating feed reduced, inferior feed was not intaked or was intaked little under the light grazing intensity, but it was intaked much under the heavy grazing intensity.(4) The live weight of Tan sheep appeared increasing tendency as the time passed under the different grazing intensity, but the live weight appeared difference after 1. October. The peak figure of ADG under the lighter grazing intensities was higher and lasted longer compared with that under the higher grazing intensities.(5) There was negative correlation between the live weight gain per sheep and the grazing intensity, it could be described as: Ga=18.48-7.01(r=-0.97**). There was positive correlation between the liveweight gain per hectare and the grazing intensity, it could be described as: Gh=0.31+17.60G-6.60G2(r=0.87*). As a result, we could primarily concluded that the grazing intensity in this type range was about 0.750sheep/hm2.(6) Feed conversion increased at first, and then decreased as the grazing intensity becomed heavier. Under the same grazing intensity, feedconversion increased at first, then decreased as the time passed.(7) After the grazing intensity overed 0.750sheep/hm2, the barren rate of tan sheep rose, the lambing percentage dropped and the pregnant time postponed. The regressional equation between the barren rate and the grazing intensity was described as: Y=-18.10+30.98X (r=0.97**). The equation between the lambing percentage and the grazing intensity was: Y=136. 50-65.68X (r=-0.95*). Therefore, the result showed that the grazing intensity ought not to surpass 0.750sheep/hm2 in this type range.(8) Considering the different research index, the grazing intensity of this type range ought not to overtake 0. 750sheep/hm2.