EFFECT OF CONCENTRATE TO ROUGHAGE RATIO AND BAKER ’ S YEAST SUPPLEMENTATION DURING HOT SEASON ON PERFORMANCE OF LACTATING BUFFALOES

sixteen lactating buffaloes after 8 weeks of calving in the 2nd to the 5th lactating season, weighing 500 to 600 kg during summer season were used in a complete switch–back design (lucas, 1956) with four groups and three successive experimentation periods. Buffaloes in the first and the second group were fed ration consisting of 60% concentrate feed mixture and 40% roughages (berseem hay and rice straw) without (G1) or with 15 g baker’s yeast (Saccharomyces cerevisiae)/head/day (G2) on DM basis. While those in the third and the fourth group were fed ration consisting of 40% concentrate feed mixture and 60% roughages on DM basis (berseem hay and rice straw) without (G3) or with 15 g baker’s yeast/head/day (G4). obtained results showed that the contents of dry matter (DM), organic matter (oM), crude protein (CP), ether extract (EE) and nitrogen free extract (nfE) tended to increase; their digestibilities and total digestible nutrients (TDn) and digestible crude protein (DCP) values increased significantly (P<0.05), however, the contents of CF and ash tended to decrease and CF digestibility decreased significantly (P<0.05) with increasing level of concentrate and decreasing roughages level. The digestibilities of all nutrients and nutritive values increased significantly (P<0.05) with barker’s yeast supplementation. The intake of DM, TDN and DCP increased significantly (P<0.05) with increasing level of concentrate and decreasing roughages level. The intake of TDN and DCP increased significantly (P<0.05) with baker’s yeast supplementation. Ruminal pH value decreased significantly (P<0.05), while ruminal total volatile fatty acids (TVFAs) and ammoniacal nitrogen (NH3N) concentrations increased significantly (P<0.05) with increasing level of concentrate. However, ruminal pH value and NH3-n concentration decreased significantly (P<0.05) and TVFAs concentration increased significantly (P<0.05) with baker’s yeast supplementation. The yield of actual milk increased significantly (P<0.05) with increasing level of concentrate, while the yield of 7% fat corrected milk (FCM) increased significantly (P<0.05) with increasing level of concentrate as well as with baker’s yeast supplementation. The contents of protein, lactose and SNF increased significantly (P<0.05), however, fat content decreased significantly with increasing level of concentrate and decreasing level of roughages. The contents of all milk constituents except ash increased significantly (P<0.05) with baker’s yeast supplementation. The amounts of DM, TDN and DCP per kg 7% FCM increased significantly (P<0.05) with increasing level of concentrate and decreasing level of roughages in the rations as well as with baker’s yeast supplementation. The average daily feed cost and feed cost per kg 7% FCM increased significantly (P<0.05), however, economic efficiency decreased significantly (P<0.05) with increasing level of concentrate and decreasing level of roughages in the rations. average daily feed cost tended to increase, but the output of 7% FCM and economic efficiency increased significantly (P<0.05), while feed cost per kg 7% FCM decreased significantly (P<0.05) with baker’s yeast supplementation. It could be concluded that lactating buffaloes fed ration consisted of 40% concentrate feed mixture and 60% roughages (berseem hay and rice straw) with 15 g baker’s yeast supplementation/head/day on DM basis (G4) showed the best results concerning milk yield, feed conversion and economic efficiency.