An experiment was carried out to evaluate the effect of diets with different calcium levels and supplemented with phytase on the performance of broiler chickens in initial (1 to 21 days of age), growing (22 to 35 days of age) and final (36 to 42 days of age) phases. Two thousand one hundred and sixty male broilers from AG Ross 308 line, from 1 to 42 days old were distributed in 6 treatments, with 6 replicates each. A completely randomized design in a 3 × 2 factorial scheme was used, with 3 phytase levels (0, 600 or 1,200 ftu/kg) and 2 calcium levels (0.94% and 0.66%; 0.84% and 0.59%; and 0.78% and 0.54% to initial, growing and final phases, respectively). The experimental diets had lower available phosphorus levels and minimum crude protein levels. At the end of each phase the weight gain, feed intake, feed conversion and death rate were evaluated. There was significant interaction between phytase and calcium levels for weight gain, feed intake and death rate in all studied phases, with best results observed for treatments constituted by 1,200 ftu/kg of phytase and lower calcium levels on the diets. No significant results were observed to FC. Nutritional calcium levels can be reduced in 30%, in diets with lower available phosphorus and minimum crude protein levels, since the diet is supplemented 1,200 ftu/kg of phytase.
available phosphorus; enzyme; poultry
