Interactive effect of calcium, citric acid, and high-dose phytase on performance of broiler chicken fed diet severely limited in phosphorus

Abstract

This study investigated interactive effect of phytase, citric acid (CTA), and calcium (Ca) concentrations on phytate phosphorus (P) utilization as evaluated by growth performance, serum Ca and P, retention of Ca and P, and bone characteristics in broiler chickens fed the diet severely limited in non-phytate P. A total of 882 ten-day-old male broiler chickens were allocated to 9 diets from 11 to 40 d of age. There were a control diet (with adequate non-phytate P concentration) and 8 diets (without any inorganic P) consisting of phytase (0 and 1500 FTU/kg), CTA (0 and 10 g/kg), and Ca (3 and 6 g/kg) in a 2 × 2 × 2 factorial arrangement of treatments with 7 pens per treatment and 14 broiler chickens per pen. Phytase supplementation or 6 g Ca/kg increased average daily gain, but the effect of phytase was more apparent in broiler chickens received 6 g Ca/kg (phytase × Ca, P < 0.01). Supplementation of phytase, CTA, or 6 g Ca/kg increased gain to feed ratio; although the effect of phytase in the diets with 6 g Ca/kg was greater in broiler chickens received no CTA supplement, the effect of phytase in the diets with 3 g Ca/kg was more apparent in broiler chickens received CTA supplement (phytase × CTA × Ca, P < 0.001). Phytase supplementation increased bone ash, bone ash percentage, and bone ash concentration, but the effect of phytase was more apparent in broiler chickens received 6 g Ca/kg (phytase × Ca, P < 0.05). Supplementation of phytase, CTA, or 6 g Ca/kg increased bone strength, but the effect of phytase was greater in broiler chickens received 6 g Ca/kg (phytase × Ca, P < 0.001) and the effect of CTA was more apparent in broiler chickens received 3 g Ca/kg (CTA × Ca, P < 0.001). Supplementation of phytase or CTA increased the P retention, but the effect of phytase was greater in broiler chickens received 3 g Ca/kg (phytase × Ca, P < 0.001) or CTA supplement (phytase × CTA, P < 0.001). In conclusion, the effect of phytase on growth performance and bone characteristics was greater than the effect of other factors, followed by the effect of Ca concentration, and the most common interaction was between phytase and Ca. Effect of phytase on growth performance and bone characteristics was greater in broiler chickens received 6 g Ca/kg.