A study was conducted with 576 mixed sex, Ross broiler chicks to evaluate the influence of different non-phytate phosphorus (NPP) levels(0.45, 0.38, and 0.31 % during starter and 0.43, 0.36, and 0.29 % during grower and finisher periods) with and without 500 FTU phytase (Ronezyme P) on performance. The experiment was conducted in a completely randomized design in 3×2 factorial arrangements (three replicate /each 32 chicks). The results showed that chicks fed with lower NPP diets had significantly lower body weight at 40 and 50d; lower daily gain during 20-40d and 0-50 d; and higher feed conversion ratio during 20-40d period. Phytase supplementation to the diets had only significantly increased feed intake during 21-40d period. The interactions between NPP levels and phytase supplementation on body weight at 40d and FCR during 0-20d was significant, in which the BW of the chicks fed lowest NPP diets was improved by phytase, whilst those of chicks fed high NPP diets was adversely affected by phytase supplementation.
