Abstract: The aims of this study was to explore the effect of “Hui Ru-kang” prescription on serum PRL,GH and STAT5 levels in dairy cow during milk withdrawal period.80 Healthy cows in late pregnancy that gave 15.42±0.71 kg milk per day were used.The cows were randomly divided into four groups:group A,B,C and D with 20 of them in each group.Dry dairy cows’ milk by gradually dry milk method and the day when cows began to dry milk was recorded as 0 d.Group A was a control group,did not feed “Hui Ru-kang”.Group B,C and D were fed “Hui Ru-kang” 400,500,600 g respectively at 8:00 am from the 1 d to the day that cows withdrawed milk completely.The cows’ venous blood was collected from the tail on the day 0,1,3,5,7,9 and 11.In addition,the daily milk production was noted.ELISA was used to evaluate the expression levels of PRL,GH and STAT5.As the result,the milk production of all 4 groups were on the decline during milk withdrawal period.Group A,B,C and D dried milk on 11,7,5 and 5 d respectively.The expression levels of serum PRL,GH and STAT5 were declining in all four groups and the decline trend of group A was slower than other groups,and the expression levels of GH and STAT5 were raised after milk withdrawal period.The change of PRL,GH,STAT5 expression levels and milk yield in group C were not significantly different between these of group D (P>0.05).The expression levels of PRL,GH,STAT5 and milk yield showed significant and positive correlation among each other (P<0.01).During milk withdrawal period,feeding 500 g “Hui Ru-kang” would make dairy cows withdraw milk obviously.

Key words: cows during milk withdrawal period, “Hui Ru-kang&rdquo, prescription, PRL, GH, STAT5