Effect of Different Diet Energy and Protein Level on Lactation Performance of Xinong Saanen Dairy Goats

In order to select the optimum energy and protein level of Xinong Saanen dairy goat during lactation period,36 healthy Xinong Saanen dairy goats were screened at the peak of lactation,whose weight(50.56±0.76)kg,parity(2-3),milk yield(2.12±0.10) kg/d,and body condition were at similar level,the goats were randomly divided into 6 groups,6 in each group.6 kinds of diets were designed by 3×2 factor randomized block experimental;the NE levels were 12.64,13.08 and 13.52 MJ/d,and the CP levels were 16.13% and 17.82% respectively.The whole trial period was 84 days,which was divided into 4 stages,each stage was 21 days.The results showed that the dietary NE and CP levels had no significant effect on DMI and blood biochemical indexes of dairy goat,but there was interaction between the test group,the treatment group with 13.52 MJ/d NE and 16.13% CP had the highest DMI milk yield were elevated with the increasing dietary NE and CP levels,the milk yield could be increased significantly by CP(P=0.041),while the milk fat,protein,lactose,dry matter and non-fat milk solids,and milk composition index decreased,the milk protein(P=0.013) and non-fat milk solids(P=0.031) could be decreased significantly by the increasing CP;there was interaction between the effects of dietary NE and CP levels on the performance of lactating dairy goat,the milk yield was highest with 17.82% CP and 13.52 MJ/d NE,while the milk quality was best with 13.08 MJ/d NE and16.13% CP.According to all indexes and the actual production,the optimum NE and CP level were 13.08 MJ/d and 16.13% respectively during lactation period of Xinong Saanen dairy goat.