A NewSlow-Release Non-Protein Nitrogen: Effects of Supplemental Level on Lactation Performance and Blood Biochemical Indices of Lactating Goats

This experiment was conducted to investigate the effects of different supplemental level of a newslow-release non-protein nitrogen (srNPN) on lactation performance and blood biochemical indices of dairy goats.Forty-eight healthy lactating Xinong Saanen dairy goats with 2 to 3 parities and about 60 kg of average body weight were randomly assigned to 4 groups with 12 goats in each group.Goats in the 4 groups were fed diets supplemented with srNPN at 0,0.25%,0.50% and 0.75%,respectively.There was a pretrial period of 1 week followed by an experimental period of 16 weeks.The results showed as follows: 1) dietary supplementation of srNPN at different levels did not affect average daily feed intake of lactating goats (P0.05).2) The supplementation of srNPN significantly increased average daily milk yield (P0.05),which in 0.50% group was significantly higher than that in the other groups (P0.05).3) Compared with that in control group,milk fat content in experimental groups was significantly increased (P0.05),but there was no significant difference among experimental groups (P0.05); besides,the contents of milk protein,lactose and milk solids-non-fat were not significantly affected by the supplementation of srNPN (P0.05).4) The supplementation of srNPN could significantly decrease blood urea nitrogen content (P0.05),and that in 0.50% group was the lowest; the contents of triglyceride,total cholesterol and total protein in blood were not significantly affected by the supplementation of srNPN (P0.05).In conclusion,dietary supplementation of srNPN can increase milk fat content and reduce blood urea nitrogen content.The average daily milk yield of lactating goats is the highest when srNPN supplemental level is 0.50%.