This study was conducted to compare between the effect of leasture yeast and local bakery yeast supplementation as non hormonal growth promoters on growth rate, nutrients digestibility, feed conversion and some blood serum parameters. Twenty buffalo male calves of about 14 months of age with an average initial live body weights of 229.2 kg were divided into four similar groups (5 animals each ) and assigned randomly to four experimental groups as follows: T1: calves were fed according to the El-Ashry (1980) allowances for maintenance + 800 g mean  daily gain and  each animal was daily supplemented with 10 g  leasture yeast (Cenzyone Tech. Inc.) with  the concentrate feed mixture. T2: calves were fed as in T1 but each animal was daily received 10 g local bakery yeast  (Saccharomyces cerevisiae) with the concentrate feed mixture.              T3  (Positive control):  as in T1 and T2 without any supplementation. T4 (negative control): calves were fed according to AnimalProduction Research Institute (APRI) (1997) allowances.The experiment lasted for six months ,after three months, the digestibility trials were conducted by using acid insoluble ash (AIA) from all animals in each group.                      The results showed that nutrients digestibility of buffalo calves  were improved by adding yeast culture in comparison with other  groups (without additive ).Also, local bakery yeast increased digestibility coefficients of DM ,CP and NFE % by 2.68 %,4.19% and 3.45 % ,respectively and decreased EE and CF digestibility by 0.36 % and 2.14%  compared  to  leasture yeast supplementation ( imported ).The differences were not significant .On the other hand ,leasture yeast supplementation had the best average daily gain (1097gm) but the lowest  was that of T4 (negative control or APRI allowances ), while, both of T2 (local yeast ) and T3 ( positive control or El- Ashry allowances ) showed intermediate value .Moreover, leasture yeast additive resulted 9.7% higher growth compared with T3 (positive control ) and 21.9 % higher growth than  of T4 (negative control ) but bakery yeast showed 5.3 % higher gain than T4 and -5.2 % lower gain than T3. Feed conversion (Kg DM /Kg gain ) was improved by adding both yeast ( T1 and T2 ) followed by T3.The best economic efficiency was recorded with T1 and T3 which fed leasture yeast and El-Ashry allowances without additive . On the other hand, results showed that no significant differences among different groups in the all intervals for blood serum parameters expect in creatinine values. These results support the recommendation of implementing this promoter in the current feeding systems of the Egyptian Buffalo calves with balanced ration or to elevate the nutritional requirements according to El-Ashry (1980) allowances.