Abstract:

Fourteen Holstein cows were divided into two groups randomly and every group included seven cows. Every cow of test group was fed 10 g Rumenal-protect-choluine every day for 30 days form ante-partum, we tested the contents of glucose, D₃Hydroxybutyrate, blood fat (triglycerides, total cholesterol, total cholesterol includes HDLC, LDLC, VLDLC), ALT and AST in the serum in six different time points， a week before parturition, 24 hours after parturition, a week after parturition, two weeks after parturition, three weeks after parturition and four weeks after parturition. All the data were dealed by independent sample T test. The results showed that daily average milk production during the first month after parturition of test group was 1.7 percent higher th0an control group; glucose in the serum of test group was kept in the normal level, higher than control group; D₃Hydroxybutyrate of test group fell down（P>0.05）; there were no evident difference of blood fat, ALT and AST between test and control groups（P>0.05）. This experiment showed RPC can release negative energy balance after parturition, prevent ketosis, help cows to recover health rapidly, and increase milk production in the first month after parturition, and improve economic benefit of cow farm. 

Key words: rumen protected choline(RPC); amount of lactation; ketone body; D_3Hydroxybutyrate; ketosis