This experiment was carried out to evaluate the effects of addition of different levels of phytase (0, 500, 1500 and 3000 units of active phytase [UFA]/kg diet) in the diets for Nile tilapia (8.88 ± 0.02 g). All diets were fed to satiation daily for 45 days. The phytase level determination was based on the performance and digestibility parameters and was estimated by the quadratic and/or the broken line models. The broken line model showed a better adjustment for phytase levels according to the observed results. Phytase supplementation increased performence, bone minerals, protein digestibility and calcium and phosphorus availability. The best results of performance, bone mineral retentions and digestibility were obtained with 700 UFA/kg of diet.
digestibility; Oreochromis niloticus; performance; phytase; Nile tilapia
