Abstract: A total of 32 Holstein dairy cows at the same parity and with close lactation stage and similar daily milk yield were randomly divided into four groups: control group,group 1,group 2,group 3.The supplementary level of extracts of puerariae radix content of control group,group 1,group 2,group 3 were 0,12.5,25,250 mg/kg respectively,the basic diet was the same.The results showed that the milk yield of experiment group were more stable than that of control group(P>0.05);the milk yield of group 1,group 2,group 3 were more than that of control group for 17.47%,9.68%,11.36%.The milk fat proportion of experiment group were raised(P>0.05),but the milk proportion of protein,SNF and density were not changed;the plasma levels of E2,COR and PRL were raised(P>0.05).Therefore,supplement extracts of puerariae radix could lessen the decline tendency of milk yield.

Key words: extracts of puerariae radix; dairy cow; estrogen; milk yield