Effect Of Ration At Different Nutrition Levels On Growth-Development And Reproductive Hormone Of Late-breed Tan Sheep

In this paper,20 healthy 7-month-old post-bred ewes tan sheep with the similar body weight were randomly assigned to five groups, namely group Ⅰ、group Ⅱ、group Ⅲ、group Ⅳ、group Ⅴ, and each of the tan ewes were fed in the single cages. Five groups were fed diets with different nutrition level, including daily ration of group Ⅲ were referenced to the NRC sheep raising standards and the actual breed situation of tan sheep feeding farm to carry on the formulation. The nutrition level of group Ⅰ and group Ⅱ were respectively 0.8 times and 0.9 times of group Ⅲ. the nutrition level of group Ⅳ and group Ⅴ were respectively 1.1 times and 1.2 times of group Ⅲ. Combining with the production performance, blood biochemical indexes, digestion and metabolism, and another indicators of reproductive hormones, and by feeding experiment and digestive metabolism experiment, all that aimed to study the suitable nutrition level of post-bred period tan ewes, and to provide theoretical basis and technical means for scientific and rational feeding tan sheep. The results showed that:In the feeding experiment,the weight of tan sheep increased fastly, and then weight gain became slowly.The growth rate of body weight declined with age increasing. The weight gain of group Ⅳ were the biggest,and the average daily gain reached to 127.22g/d. Under the condition of the experiment, with the improvement of dietary nutrient level, the body weight,average daily gain and feed intake of dry matter of tan ewes were significantly increased (P<0.05), furthermore, feed-weight ratio continuously declined. There were no significant different in the variation of body length, body height and pipe circumference(P>0.05),but there was significant different in the growth of the chest circumference(P<0.05).The regular patterns of chest circumference growth were similar to the growth of body weight. In general, the nutrition level of feed can significantly affect the weight gain of post-breed tan sheep, and suitable nutrition level(CP:15.94%, ME:10.18MJ/Kg) can significantly improve the growth and development, production performance of tan sheep, as well as obtain the highest economic benefit.The nutrition levels of the ration significantly influenced the content of BUN of the post-breed tan ewes(.P<0.05), but there were no significant effect on the content of TG (P>0.05). Within a certain range, the nutrition levels of the diet had remarkable influences on the content of GLU and TP of the late-breeding tan ewes(P<0.05).In the experiment, the nutrition levels of diet had effect on serum estrogen and progesterone levels of the late-breeding tan ewes, however, the effect was not significant. With the improvement of nutrition levels, serum estradiol and progesterone were increased to different extent.The nutrition levels of the diet had no significant effect on the apparent digestibility of dry matter (P>0.05), but significantly influenced the apparent digestibility of crude protein, energy, ADF and NDF(P>0.05). In the experiment, when the nutrition level was (CP:14.50%; ME: 9.25MJ/Kg),the apparent digestibility of CP,ADF and NDF reached the largest,at the same time,when the nutrition level was(CP:15.95%; ME:10.18MJ/Kg),the apparent digestibility of energy was the largest.Thus, the most suitable nutrition level was (CP:14.50%; ME: 9.25MJ/Kg),under this condition,the apparent digestibility of nutrients was larger, and the utilization efficiency and biological value of nitrogen were largest.Above all, combining with the production performance, blood biochemical indexes, reproductive hormone and digestion and metabolism indexes of tan sheep, we draw the conclusion that the suitable nutrition level for late-breeding tan ewes was (CP:14.50%～ 15.95%, ME:9.25～10.18MJ/Kg).