Effect of microbial phytase on the performance of broilers fed on low phosphorus diets*

Six experimental diets were offered to triplicate groups of 12 broiler chicks from day old to 8 wks of age. These treatments were standard broiler ration (T₁), broilers ration with 0.3 percent available phosphorus (AP) (T₂), broiler ration with 0.4 percent AP (T₃), standard broiler ration with 750 U of phytase per kg of feed (T₄), broiler ration with 0.3 percent AP supplemented with 750 U of phytase per kg of feed (T₆). The groups fed standard broiler rations with and without phytase and those fed rations containing an AP of 0.4 percent supplemented with phytase had significantly (P<0.01) higher body weights than other treatments. All enzyme supplemented treatments consumed significantly (P<0.01) more feed than their respective unsupplemented groups except in the group offered 0.4 per cent AP. Significantly (P<0.01) superior feed efficiency was recorded in groups fed a diet having 0.4 percent AP supplemented with phytase. The percent dressed yield and ready-to-cook yield were significantly (P<0.01) higher in groups fed a diet having 0.4 percent AP supplemented with phytase than other groups. The percent giblet yield was significantly (P<0.01) more ingroup fed a standard diet supplemented with phytase than other groups. Blood samples and left tibia were collected from six birds of each group at eighth week of age. Tibial ash, serum calcium, inorganic phosphorous, serum alkaline phosphatase (ALP), tibial calcium and phosphorous were estimated at the end of eight weeks of age. Phytase supplementation has a positive effect on eighth week tibial ash. Serum calcium and inorganic phosphorous were not significantly influenced at eighth week of age between the treatment groups. The serum alkaline phosphatase, tibial calcium phosphorous was significantly (P<0.01) higher in enzyme-supplemented groups compared to their respective un-supplemented groups.