Effect of citric acid, vitamin D3, and high-dose phytase on performance of broiler chicken fed diet severely limited in non-phytate phosphorus

Abstract

This study investigated effect of various combinations of phytase, citric acid (CA), and vitamin D3 (D3) on phytate P utilization as evaluated by growth performance, serum minerals, and bone characteristics in broiler chickens fed the diet severely limited in non-phytate P. A total of 585 ten-day-old male broiler chickens were allocated to 9 diets from 11 to 38 d of age. There were a positive control (with adequate non-phytate P concentration and 2,000 IU D3/kg in the diet) and 8 diets (without any inorganic P) consisting of D3 (2,000 and 4,000 IU/kg), CA (0 and 15 g/kg), and phytase (0 and 1,500 FTU/kg) in a 2 × 2 × 2 factorial arrangement of treatments with 5 pens per treatment and 13 broiler chickens per pen. Phytase supplementation increased average daily gain and decreased feed to gain ratio, but the effect of phytase was more apparent in broiler chickens received CA (phytase × CA, P < 0.05 and P < 0.01 for average daily gain and feed to gain ratio, respectively). Serum P was increased by phytase supplementation and decreased by CA supplementation, but the decreasing effect of CA was not observed in broiler chickens received phytase (phytase × CA, P < 0.05). Addition of 4,000 IU D3/kg increased breast muscle yield (P < 0.05) and decreased abdominal fat pad (P < 0.05). Phytase supplementation increased carcass yield (P < 0.05) and breast muscle yield (P < 0.001). The individual use of phytase increased bone ash percentage and the combination of 4,000 IU D3/kg and CA increased it, but the inclusion of phytase, CA, and 4,000 IU D3/kg simultaneously did not increase further bone ash percentage (phytase × CA × D3, P < 0.05). Bone strength was increased by phytase supplementation and not affected by supplementation of CA or 4,000 IU D3/kg, but the effect of phytase was more apparent in broiler chickens received CA or 4,000 IU D3/kg; however, the inclusion of phytase, CA, and 4,000 IU D3/kg simultaneously did not increase further bone strength (phytase × CA × D3, P < 0.01). In conclusion, the combination of phytase and CA was more effective than other possible combinations in improving growth performance of broiler chickens fed a diet severely limited in non-phytate P.