Effect of citric acid and microbial phytase on growth performance and some carcass traits of broilers

A total of 270 Ross 308 male broilers from 7 to 42 days old were used in a 3×3 factorial arrangement design with three levels of citric acids (0, 3 and 6%) and three levels of phytase enzyme (0, 500 and 1000 enzyme IU/kg) on a randomized complete block design, with 9 experimental diets, 3 replicates and 10 birds per each replicate. The diets were formulated based upon corn-soybean meal. Feed intake (FI), weight gain (WG), feed conversion ratio (FCR), carcass yield and relative carcass weight factors were measured and analyzed throughout the experimental period. The diets containing citric acid had a significant effect (P<0.01) on feed intake, weight gain and carcass yield and had no significant effect on FCR and carcass factors. Weight gain and relative neck weight were significantly (P<0.05) affected by using microbial phytase enzyme, but had no significance effect on feed intake, feed conversion ratio and other carcass factors. Adding citric acid to diets containing phytase enzyme improved performance and carcass traits, therefore, the results showing that citric acid probably has a synergetic effect on phytase efficiency in broilers.