Objective  To investigate the effects of different microecological preparations on rumen fermentation parameters and digestive tract enzymes of Hu sheep lambs in the hope of providing data reference for improving rumen development and health status of lambs.

Methods Forty-eight 8-days lambs with similar body weight (3.00 ± 0.20) kg in good health were randomly divided into 3 treatment groups with 4 replicates per group and 4 sheep per replicate. Control group was fed a basal diet, experiment group 1 was fed the basal diet supplemented with 2.2% microecological preparation Ⅰ (Clostridium butyricum∶Bacillus subtilis = 4∶5), experiment group 2 was fed the basal diet supplemented with 2.2% microecological preparation Ⅱ (Clostridium butyricum∶Bacillus subtilis∶fructooligosaccharides = 4∶5∶5). Lambs at 15 days of age were fed the starter diet and the trial period lasted for 40 days.

Results The results showed as follows: Body weight (BW), average daily feed intake (SI) and average daily gain (ADG) among treatment groups had no significant effects compared with control group (P>0.05); Rumen pH, NH₃-N concentration, lactic acid, isobutyric acid, valeric acid and isovaleric acid concentration of lambs in all treatment groups were not significantly different from those in control group (P>0.05); Acetic acid, propionic acid, butyric acid and total volatile fatty acids in trial group 1 were significantly lower than those in control group (P<0.05); Trypsin activity and Chymotrypain activity in trial group 1 were significantly decreased compared with control group (P<0.05), and there was no significant difference between experimental group 2 and control group (P>0.05); The cellulase activity in trial groups 1 and 2 was significantly lower than that in control group (P<0.05); The apparent digestibility of dry matter DM, organic matter OM and crude fat EE among treatment groups had no significant effects compared with control group (P>0.05).

Conclusion Microecological preparations have no significant effect on the growth and digestive performance of 15～54 days Hu lambs, but altered the ruminal fermentation parameters and intestinal digestive enzyme activity.