Abstract: In an attempt to investigate the impact of dietary supplementation of a Chinese herbal medicine compound additive on activity of ruminal digestive enzymes in sheep,a total of 60 four-month-old healthy Dorper and Small-tailed Han sheep crossbred lambs (F1) of were randomly assigned into the following four groups: the male and female control groups were fed with the basal diet,and the male and female experimental groups fed the basal diet supplemented with Chinese herbal medicine compound additive.The feeding experiment lasted for 45 days.At the end of the experiment,the rumen fluid samples were collected from the lambs,and the activity of protease,carboxymethyl cellulase and alpha-amylase in rumen fluid of the lambs in different groups were determined and statistically analyzed.The results demonstrated that while the dietary supplementation of Chinese herbal medicine compound additive had no significant impact on activity of ruminal protease and alpha-amylase in the crossbred lambs (P>0.05),it significantly elevated the activity of ruminal carboxymethyl cellulase (P<0.05).In addition,the variation of the three tested ruminal digestive enzymes expressed no association with the lambs′ gender.Our results suggest that the dietary supplementation of Chinese herbal medicine compound additive is able to improve the activity of ruminal carboxymethyl cellulase in lambs and thus can promote the digestion and metabolism of forage cellulose in sheep rumen.