Effects of Dietary Available Phosphorus and Microbial Phytase on Growth Performance, Carcass Traits, Serum Minerals and Toe Ash Content in Broiler Chicks

Effect of dietary phosphorus and microbial phytase was investigated on the growth performance, carcass, toe ash and serum Ca and P parameters using 160 Ross-308 broiler chicks. For this purpose, phosphorus low (0.329, 0.265 & 0.219%) and very low (0.251, 0.200, 0.145%) levels of available phosphorus (AP) were used for starter, grower and finisher periods, respectively. two Microbial phytase (MP) was used at 400 and 800 FTU/kg levels in each period. Experiments were laid in 2x2 factorial arrangements with 4 replications and 10 birds per each replicate. The interactive effect of APxMP for growth performance, serum Ca and P and toe ash content was not significant (p > 0.05); whereas it was significant (p < 0.01) for carcass and liver percent. Data of main effects indicated that lowering AP levels caused a decrease (p < 0.01) in weight gain and worse FCR (p < 0.01) at the starter, grower and overall of experiment period (0-49 d), but 800 FTU/kg of MP improved (p < 0.01) weight gain and FCR at said periods. Carcass, breast, thighs and toe ash percent was affected (p < 0.01) by very low AP and decreased. MP @ 800 FTU/kg increased (p < 0.05) toe ash percent. An increase in Ca and decrease in P levels of blood serum was observed (p < 0.01) with very low AP. Results indicated that interaction effects of APxMP could not affect the growth performance, toe ash, serum minerals and carcass traits except carcass percent and make it better in birds fed low AP diets. (C) 2011 Friends Science Publishers