Effect of Chromium Propionate Substituting 25% Rumen-protected Choline on Production Performance and Blood Indicators of Perinatal Dairy Cows

The object of this study was to investigate the effects of chromium propionate replacing 25% rumen-protected choline (RPC) on production performance and blood indicators of perinatal dairy cows.According to the principle of ensuring that chromium propionate and RPC were fed 14 days prepartum,27 healthy Holstein cows (age,parity,lactation volume,body condition and expectancy were similar) were randomly divided into three groups (GroupsⅠ,Ⅱ and Ⅲ),with nine cows in each group.Cows in GroupⅠwere fed basal diets;cows in GroupⅡwere fed the same basal diets with 10 g·dRPC per cow;and cows in Group Ⅲwere fed the same basal diets,but 7.5 g RPC and 2.5 g chromium propionate (4 mg chromium) per cow.The results showed that dry matter intake (DMI) of prepartum in GroupsⅡand Ⅲ was significantly increased (P<0.05),compared with GroupⅠ;however,there was no significant difference between Groups Ⅱ and Ⅲ (P>0.05).The milk fat content in Group Ⅲ was significantly higher than that in Group Ⅰ on the 7th day of postpartum (P<0.05).The urea nitrogen content in Groups Ⅱ and Ⅲ significantly lower than that in GroupⅠon the 21st day of postpartum (P<0.05),but there were no significant difference between Groups Ⅱ and Ⅲ (P>0.05).The somatic cell counts in Group Ⅲ were significantly lower than those in GroupsⅠand Ⅱ on the 14th and 21st days of postpartum (P<0.05).The contents of the total cholesterol in Group Ⅲ decreased significantly compared to Group Ⅱ on the 7th day of prepartum,on the day of calving and the 7th day of postpartum (P<0.05).The concentration of high-density lipoprotein (HDL) in Group Ⅲ was significantly higher than that in Group Ⅱ on the 7th day of prepartum,on the day of calving and the 7th day of postpartum (P<0.05).On the 7th day of postpartum the concentration of insulin in Group Ⅲ was obviously higher than that in Group Ⅱ (P<0.05).In summary,replacing 25% of rumen-protected choline with chromium propionate reduced production costs and improved dairy farming benefits.