This study was carried out to investigate the effects of formulating diets varying in non-phytate phosphorus levels (0.45, 0.38 and 0.31 % during the starter and 0.43, 0.36 and 0.29 % during the grower and finisher periods, respectively) with 500 F.T.U of either Natuphos or Ronozyme-P phytase on performance in broiler chicks. Ross straight-run broiler chicks (n=576) were allocated to six dietary treatments, each replicated three times (32 chicks per pen) in a completely randomized design in a 3×2 factorial arrangements. The results indicated that the chicks fed diet containing lower NPP levels had significantly lower body weight at 40 and 50 d; lower daily gain during 21-40d; and higher feed conversion ratio during 21-40d period. The broiler performance was not affected by either source of phytase or the interaction between phytase source and NPP levels.
