| The aim of this study was to investigate the effects of different levels of rumen-protected choline chloride(RPC)on milk production,milk composition and some blood biochemical indicators during the perinatal period of dairy cows,and to explore the effect of RPC on the corresponding blood parameters of dairy cows.Provide an experimental basis for RPC production in dairy production.In this experiment,42 Chinese Holstein cows with similar milk production,age,parity and expected maturity,healthy body condition and pre-perinatal period were selected,and were randomly divided into 7 groups according to single factor,with 6 groups in each group.The trial ended 21 days before the expected date of delivery and ended 21 days after delivery.The control group only fed the basal diet and did not add any products;the test group Ⅰ,Ⅱ,Ⅲ added RPC from the postpartum period,the added amount was 10 g /(d·head),20 g /(d·head),30 g /(d·Head);In the Ⅳ,Ⅴ,and Ⅵ groups,RPC was added to the basal diet from the 21 st day before the birth,until the end of the experiment,and the RPC addition amount was added according to the Ⅰ,Ⅱand Ⅲ groups.The results of this test showed that there was no significant difference in milk yield between the groups of cows during the test period.However,at 15 days of DIM,the average milk yield of dairy cows with RPC of 10g/d,20g/d and 30g/d was increased by 1.56kg/head,1.74kg/head,and 2.71kg/head,respectively.There was no difference between the milk production of the choline group and the control group in the late perinatal period.And when the total amount of RPC added during the perinatal period is 30g/d,the cows have the highest average milk yield.Analysis of the milk components of each group showed that the milk fat content,protein content and the difference between lactose and non-solid matter in the milk of each group were not significant.In this experiment,the plasma glucose content of each group of cows decreased with time.The plasma glucose level of the RPC group was slower than that of the control group,and the glucose level of the two groups with the RPC of 20g/d and 30g/d was the slowest.In the two weeks after birth and three weeks after delivery,the plasma glucose levels of the two groups of cows with RPC of 20g/d and 30g/d were significantly higher than the other groups.The plasma BHBA content of dairy cows with RPC of 20g/d and 30g/d decreased during the perinatal period.At 2 weeks postpartum,the plasma BHBA content of the cows in the whole perinatal period was significantly lower than that in the control group.The results of plasma triglyceride levels showed that the plasma triglyceride content of 30g/d cows was significantly higher than that of the control group at the late perinatal period,and was significantly lower than the whole perinatal period with an added RPC of 20g/d.30 g / d these two groups.In this study,the addition of RPC can improve the liver function of dairy cows during perinatal period.The ALT and AST indicators showed that the AST content of RPC group was significantly lower than that of the control group at 1 week postpartum.And the whole perinatal period added RPC to 20 g / d and 30 g / d group,the ALT and AST indicators of the cows during the perinatal period remain relatively low levels,two weeks after delivery and three weeks after delivery,the two groups of cows ALT And AST levels were significantly lower than the control group.In addition,the cows were fed 20g/d and 30g/d RPC in the perinatal period.Compared with other test groups,they effectively increased the blood sugar level of peripartum cows,significantly reduced the content of BHBA and triglycerides,and improved the cows.The liver function effectively relieves the negative balance of energy in the cow,thereby increasing the milk yield of the cow and increasing the nutrients in the milk. |
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