RESUMEN
Survey on influence of citric acid and microbial phytase enzyme on performance and phytate phosphorus utilization in broiler chicks fed a corn-soybean meal diet. Completely randomized design with a 3x2 factorial arrangement. Two hundred and fifty two one-day-old commercial broiler chicks [Ross -308] were divided into 7 groups of 36 chicks each. Three levels of citric acid [0.0, 2.5% and 5%] and two levels of microbial phytase [0.0 and 500 units/kg] in low available phosphorus diets were used. The criteria used to assess were growth performance, alkaline phosphatase [ALP] enzyme activity, plasma calcium and phosphorus [P] levels, tibia ash and carcass yield. Citric acid significantly improved weight gain and feed conversion ratio [p<0.05]. It had no effect on feed consumption, tibia ash and carcass yield in different growth performance periods Interaction of the effect citric acid x phytase on the body weight gain and feed conversion ratio was significant [p<0.01]. Inclusion of microbial phytase improved growth performance, plasma P levels and tibia ash. Adding of citric acid and microbial phytase did not affect carcass yield. While, adding of citric acid to low available phosphrus diets reduced plasma ALP and mortality rate [p<0.01], increased plasma P levels [p<0.01]