摘要The effects of yeast culture and directfed microbes on the growth performance of weaner lambs was examined.Thirty-two Hu lambs with inihtial weight of 22.20 ( + 0.75 ) kg were randomly assigned to one of four treatments:basal diet without additive (control),added with yeast culture at 15 g/head/d (YEC),YEC plus Bacillus licheniformis preparation at 2.3 g/head/d (YBL) or plus Clostridium butyricum preparation at 2.3 g/head/d (YCB).The feeding trial lasted 75 d with 15 d for adaptation. Feed intake was not influenced (P＞0.05) by treatment.Average daily gain of growing lambs was 102,114,90,and 89 g/d in control,YEC,YBL,and YCB,respectively,with no significant difference (P ＞ 0.05) among treatments,but the carcass weight of YEC lambs was significantly higher (P ＜0.05) than that of other treatments.Total volatile fatty acids and acetate to propionate ratio in the rumen were unaffected,although the butyric acid concentration was higher ( P ＜ 0.05 ) in the mmen fluid of YCB lambs compared with YEC lambs and slightly higher (P ＞ 0.05) than in controls and YBL lambs.Solid-associated fungi population relative to total rumen bacteria 16S ribosomal DNA was significantly lower ( P ＜ 0.05 ) in YBL lambs ( 3.55 )compared with those on YCB (23.12 ).There was little difference in blood glucose and plasma urea-N concentrations among the treatments.Blood concentrations of creatinine and globulin were significantly higher ( P ＜ 0.05 ) in YBL lambs,compared with the control and YEC-fed animals,and no difference with YCB lambs.Total protein and triglycerides in blood were significantly (P ＜ 0.05 ) higher in YBL lambs,compared with controls.These serum biochemical parameters suggest that treatment increased amounts of absorbable protein but not efficiency of protein utilization and in YBL and YCB lambs.The results indicated that yeast culture improve growth performance,while little advantage could be expected from combining yeast culture with either the B.licheniformis preparation or C.butyricum preparation.More research using lower doses of B.licheniformis preparation or C.butyricum preparation in combination with yeast culture is warranted.