SUMMARY

The objectives of this study were to evaluate the effect of levels yeast supplementation as a natural feed additive on growth performance, carcasses characteristic and some blood metabolites of growing Sohagi lambs. For this purpose, twenty-one Sohagi lambs (27.00±0.75 kg body weight, 6 months old) were randomly assigned to three dietary treatments with seven lambs per treatment. The treatment groups were as follows:(G1) was kept as a control and fed a basal diet consisting of roughage and concentrate mixture. (G2) fed the basal diet supplemented with 0.5 % of yeast culture (YC) (Saccharomyces cerevisiae) to the mixture, while (G3) received the same basal diet supplemented with 1% of YC. All animals were fed 60% of their requirements as concentrate mixture with crushed corn stover given ad libitum. The quantity of concentrate mixture was adjusted every month according to change in body weight. The results indicated that dietary supplementation of YC (0.5 or 1%)did not significantly affect on body weight and daily gain. However, dry matter intake (DMI) of concentrate, roughage and total dry matter intake were significantly (P<0.05) higher for lambs fed YC than control. Supplemented YC to lambs rations decreased significantly (P<0.05) feed conversion ratio in comparison with the control treatment. Serum glucose and urea nitrogen were increased significantly (P<0.05) in YC groups. However, the concentration of triglycerides and cholesterol decreased significantly (p<0.05) when feeding YC diets. No differences were observed between treatments for hot carcass and carcass cuts with respect to flank, which recorded higher (p<0.05) value for YC groups compared to control. Supplemented YC at level of 0.5% or 1% significantly (P<0.05) increased dry matter and fat in meat compared with control groups. Water-holding capacity was significantly (P<0.05) lower for YC groups than control. It was concluded that caring of animal management led to improvement productive performance of sheep, blood metabolites and carcass characteristics via dietary yeast supplementation. Also, YC may be more useful as a feed additive for growing lambs rations.