This experiment was carried out using 1200 Arian broiler chickens to evaluate the interaction effects of between different levels of dietary electrolyte balance and microbial phytase on performance. A 4×3 factorial arrangement of treatments was used with 4 levels of dietary electrolyte balance (200, 225, 250 and 275 mEq/kg of diet) and 3 levels of microbial phytase (0, 500 and 750 phytase units/kg of diets). Results showed that the main effect of the dietary electrolyte balance was significant (P < 0.05) for feed intake, feed conversion ratio and body weight in 42 d of age, whereas effect of the dietary electrolyte balance was not significant (P > 0.05) for other productive traits. Also, the main effect of phytase was significant (P < 0.05) for feed intake, weight gain, body weight, livability and production index. The dietary electrolyte balance and microbial phytase interaction was significant for all productive traits (P < 0.05). In this case, supplemental phytase improved the body weight, weight gains and production index at all dietary electrolyte balance levels. The overall results of the present study suggest that the microbial phytase is more likely to enhance the body weight and weight gain of broiler chickens in diets with low dietary electrolyte balance.
