Effects of phytase supplementation and different levels of formaldehyde in diet on growth performance, carcass traits, immune system and blood parameters of broiler chickens

This research was conducted to investigate the effect of different inclusion rates of formaldehyde in diet with or without supplementation with phytase on growth performance, carcass and immune system of broiler chickens. The experiment was done in a 2×3 factorial arrangement including three levels of formaldehyde (0, 2 and 6 ml/kg of diet) and two levels (with or without) of phytase supplementation. A total of 360 day-old broiler chickens (Ross 308) were used in six treatments and there were four replicates for each treatment. The results indicated that the interaction effect and the main effect of phytase supplementation on feed intake were significant in the starter phase (p<0.05). The results of growth performance showed that the interaction effect was on the weight gain in grower, finisher and total periods (p<0.05). Besides, the body weight gain of the broiler chickens was influenced by the main effect of phytase supplementation (p<0.05). The results showed that addition of formaldehyde into the diets altered the weight gain of broiler chickens in the grower phase (p<0.05). The results of the evaluation of internal organs indicated that interaction effect and the main effect of phytase had a significant effect on the weight of abdominal fat (p<0.05). The concentration of Aspartate aminotransferase (AST) as a liver enzyme was affected by interaction effect and the main effect of phytase supplementation (p<0.05). It is concluded that phytase supplementation improved the body weight gain of broilers. However, addition of formaldehyde had no negative effect on growth performance of broiler chickens.