Effect Of N-Carbamylglutamate Supplementation On Milk Performance Blood Metabolites And Immunity In Transition Cows

The purpose of this study was to reveal the effect of adding N-Carbamylglutamate on lactation performance,immune function and hormones of dairy cow in transition period.80 head of prepartum Holstein dairy cows were selected according to the similar body weight,parity,milk yield in the last lactation and body condition score.The cows were randomly allotted to 4 groups,with 20 each group.Group?,before 3 weeks before predicted calving,20 g was added in the basic diet every day until 0d calving;group ? started from d0 postpartum and ended d10 post-calving in the same way;group ?started from 21 d before calving and ended 21 d after calving in the same way;control group only fed the basal diet without an supplementation.The blood samples were taken for physiological and biochemical indexes analysis.Milk samples were taken and investigated periodically.The results showed that:(1)Milk yields of dairy cows in group?significantly increased at d15 postpartum(P<0.05)and d20 postpartum(P<0.05).At d10 post-calving,supplementation of NCG had no effect on the percentages of milk fat,milk lactose,SCC and MUN(P>0.05).The percentages of milk protein of dairy cows in group ?significantly increased compared to the control group and group?(P<0.05).But NCG supplementation had no effects on the yield of milk protein,milk fat and milk lactose.At d20 post-calving,the percentages of milk protein significantly increased compared to the control group(P<0.05).The MUN of dairy cows in group ? was significantly lower than that of group?and group?.NCG supplementation had no effects on the percentages of milk fat,milk lactose and SCC.But the yield of milk protein and milk lactose of dairy cows in group ? and group ?significantly increased compared to the control group(P<0.01).(2)The superoxide dismutase(SOD)level in the group ? lower than the other groups(P<0.05)at 10 days before calving.NCG supplementation had no effects on the superoxide dismutase(SOD)level in newborn calves.NCG supplementation had no effects on the IgG in milk first(P>0.05).(3)Glu were significantly higher on 0d calving in group?than in control group(P<0.05).Sermn AST activities were significantly lower in postmartum 21 d in the group ?(P<0.05).(4)Serum PRL concentrations were significantly changed on 0d calving in group ? whencompared with group?,?and control group(P<0.05).In summary,supplement on 20 g/d of NCG on transition cows can improve milk production performance,and group?(started from d0 postpartum and ended d10 post-calving)and group ?(started from 21 d before calving and ended 21 d after calving)effect better than others.Supplement on NCG on transition cows had little effect on neonatal calves,and had no effect on immune and antioxidant capacity.