Effect of feeding different levels of available phosphorus, vitamin D3 and phytase on growth, immune response and carcass quality traits in broiler chickens

A six weeks (0-6wks) feeding trial was conducted involving two levels of AP (0.45, 0.35 and 0.35, 0.25 % during starter and finisher phase, respectively), two levels of vitamin D3 (1500 and 3000 IU/kg) and two levels of phytase (0 and 500 FTU/Kg) in a 2x2x2 factorial experiment to assess the performance of broiler chickens (n=320). Significantly (P<0.05) higher body weight was observed in dietary combination of API and 3000 IU/kg vitamin D3 with no added phytase than the AP2 and 1500 or 3000 IU/kg vitamin D3 with added phytase. Body weight gain during 0-3wks (P<0.01) and 0-6wks (P<0.05) was higher in the birds fed AP1 diet than the AP2 diet, however no such differences were observed in vitamin D3 or phytase supplemented birds. Feed intake during 0–6 weeks differed significantly due to different levels of AP. Significantly (P<0.01) higher humoral immune response (HA titre to SRBC) was observed in birds fed AP2 with addition of phytase than the AP1 without phytase enzyme. There were no differences in the carcass yields of the birds fed combinations of AP, vitamin D3 and phytase. It is concluded that a dietary concentrations of 0.35 and 0.25% AP during starting (0–21 d) and finishing phase (21-42d), respectively and 3000 IU/kg vitamin D3 without phytase supplementation was found optimum for growth, however for immunity AP2 with addition of phytase was found better in broiler chicken.