The Study Of Effects Of Different Nutritional Levels Diet On Reproductive Performance Of Ewes

The general breeding of sheeps at prairie is grazing, so the feed intake of nutrients can not satisfy their production needs. The objective of this study was to evaluate the influence of supplementary feeding of sheep before mating on weight and reproductive performance, therefore analyzed the existing problems in pastoral sheep farming, so that we can provide the oretical guidance for local herdsmen, also aiming at increasing herdsmen’s income by improving pastoral sheep reproduction rate through optimizing diets. Experimental study of this paper consists of two parts:Experiment one mainly studied nutrition intake of grazing sheep in breeding seasons and analyzed if the intake nutritional levels of these grazing sheep met their demand. Results showed that feed intake of grazing Mongolia sheep was 1.16kg when adopting intake prediction model of Huang, which is lower than the demand of mutton sheep in China and Inner Mongolia fine wool sheep of similar body weight, and lower than dry matter requirements of 40kg sheep under NRC nutrition standards as well. Crude protein (CP) and gross energy of sheep in the experiment was 128.76 g and 20.75MJ/kg respectively, in which CP level did not meet the demand of the requirements and NRC standards of mutton sheep in China and Inner Mongolia fine wool sheep, whereas gross energy is also lower than the requirements of mutton sheep in China and Inner Mongolia fine wool sheep, but similar to NRC standards.Experiment two mainly evaluated the influence of supplementary feeding of different nutritional levels on reproductive performance of grazing sheep. Weight change of grazing sheep has been studied through flushing before mating, reproductive performance of grazing sheep has been studied after estrus synchronization and artificial insemination. Results showed that there are huge impact of supplementary feeding on weight changes of ewe before mating, Average Daily Gain (ADG) of groups with supplementary feeding (high energy group, medium energy group and nitrogen balance group) was higher than control group significantly (P<0.05), yet no significant differences among groups with supplementary feeding had been observed (P>0.05). Compared to the control group, Average daily absolute weight of supplementary feeding groups was 139g. Average lambing rate of supplementary groups in the first estrus was 117.67%, and that of control group was 105.20%, among which group A had the highest double lamb rate, reaching at 22.92%. Pregnancy rate of supplement groups and control group increased by 8.2-18.0% and 2.6% separately. Average birth weight of lambs from supplement groups was 4.09kg, and for control group the figure was 3.97kg. Maximum weight of the lamb was 4.96±0.43kg, minimum weight was 3.03±0.13kg, double lamb had an average weight of 2.69±0.20kg. In conclusion, it has some positive effects of supplementing feeding before mating.