Influence of Citric Acid and Microbial Phytase on Growth Performance and Carcass Characteristics of Broiler Chickens

Problem statement: The aim of this study was to investigated the effects of adding citric acid and microbial phytase supplementation (Natuphos^®) on growth performance and carcass characteristics of broiler chickens fed corn soybean meal base diets. Approach: The experiment included nine treatments with 10 birds in each replicate using a 3×3 factorial design for two main factors of citric acid (0, 3 and 6%) and three phytase enzyme (0, 500 and 1000 IU kg⁻¹). The diets were formulated based upon corn-soybean meal 7 to 21 and 22 to 42 day periods. Results: Using different levels of citric acid in diets had no effect on internal organs (except relative heart weight), whereas, diets containing 6% citric acid decreased feed intake, body weight gain and carcass yield (p<0.05) and improved feed conversion ratio and organs relative weight. Also, microbial phytase caused increase in feed intake, weight gain and relative neck weight (p<0.05). Conclusion: Depression of performance was differently affected by citric acid levels. Also, there was an additive effect between microbial phytase and citric acid.