Effect of Different Diet Energy Levels on Milk Yield and Milk Composition of Xi'nong Saanen Dairy Goats

In order to sift the best energy level of complete feed of lactation Xi'nong Saanen dairy goats,36 healthy Xi'nong Saanen dairy female goats with the similar body weight(50.56±0.76) kg,parity(2-3),delivery date,milk yield(2.12±0.10)kg/d and body condition were randomly divided into 4 groups.Diet with the energy level of 12.53、12.80、13.07 and 13.19 MJ/Kg were fed to the four groups respectively.The whole experiment period was 63 days with the pre-feeding period of 7 days.The result showed,along with the increase of diet energy level,both of the quatity of feed intake and milk yield went up first and then down.Moreover,the goats fed with 12.8 MJ/Kg energy diet got the most diet intake,and the goats fed with 13.07 MJ/Kg energy diet got the highest milk yield.In addition,different energy levels had no significant effect on the milk composition and the blood index.