Performance of Broiler Chickens Fed Low Non Phytate Phosphorus Diets Supplemented with Microbial Phytase

An experiment was conducted with 270 broiler chicks to examine the effect of microbial phytase supplementation to low non-phytate phosphorus (NPP) diets on growth performance, bone mineralisation and nutrients retention during 1 to 21 days of age. Four isonitrogenous and isocaloric diets were formulated to contain 0.30, 0.35, 0.40 and 0.45% NPP with the two lowest NPP levels (0.30 and 0.35%) supplemented with microbial phytase (500FTU per kg diet). Each diet was offered ad libitum to 9 replicates of 5 chicks each throughout the experimental period. The performance in terms of body weight gain, feed intake and feed/gain was significantly depressed in chicks fed lowest level of NPP (0.30%). Supplementation of phytase to either 0.30 or 0.35% NPP diet significantly improved body weight gain and feed conversion, which was comparable with 0.40% NPP diet. The leg abnormality increased and, tibia ash and tibia breaking strength decreased significantly in diets containing 0.30 and 0.35% NPP. Increasing NPP level to 0.40% or supplementing 500FTU phytase/kg diet to 0.30 and 0.35% NPP diets alleviated leg abnormality and enhanced tibia breaking strength and ash content. Serum Ca concentration was not influenced, but serum concentration of P and protein increased significantly either by enhancing NPP content to 0.40% or supplementing microbial phytase to 0.30 and 0.35% NPP diet. The nitrogen retention was significantly higher in 0.40% NPP diet compared with lower levels (0.30 or 0.35% NPP). Supplementation of microbial phytase to low NPP diet (0.30 and 0.35%) significantly increased nitrogen retention. The excretion of nitrogen decreased significantly in phytase-supplemented group compared with that of either 0.40 or 0.45% NPP diet. It is concluded that microbial phytase supplementation (500FTU/kg diet) to low NPP (0.30%) maize-soybean meal based poultry diets enhanced performance, increased retention nutrients (N, Ca and P) and improved bone mineralisation.