Evaluation of high dietary phytase supplementation on performance, bone mineralization, and apparent ileal digestible energy of growing broilers.

The present study was conducted to evaluate four commercially available phytase sources supplemented at regular (R) and super-dose (S) levels on live performance, bone mineralization, and apparent ileal digestible energy. Broiler chickens were allocated in stainless steel battery brooders (six birds per cage and eight pen replicates per treatment). A basal diet formulated to contain 0.2% non-phytate phosphorus (NPP) and 0.7% Ca was subdivided to create 11 dietary treatments: (1) basal diet was kept as the negative control (NC); (2) NC + limestone and monoclacium phosphate to create positive controls 1 and 2 formulated to yield 0.3% and 0.4% NPP; (3) NC + phytase A (250 and 1,500 FTU/kg); (4) NC + phytase B (500 and 1,500 FTU/kg); (5) NC + phytase C (500 and 1,000 FTU/kg); (6) NC + phytase D (1,000 and 2,000 FYT/kg). Performance was evaluated on d 7, 14, and 22. Tibia bone ash, tibia breaking strength, bone mineral content, and bone mineral density were evaluated on d 22. Apparent energy digestibility was evaluated on d 24. At d 7, phytases A and C supplemented at S level improved (P < 0.05) body weight and weight gain when compared to the NC. At d 14 and 22, all phytase sources improved (P < 0.05) body weight, weight gain, and bone mineralization when compared to the chicks under the NC diet. Overall, phytase supplementation at S level improved 17% apparent ileal digestibility at 24 d. Throughout the grow out period, phytase super-dose yield (P < 0.05) better performance, bone characteristics, and energy digestibility than the regular dietary level. In conclusion, all phytase sources were able to compensate the phosphorus deficiency and promote performance and bone mineralization. High levels of phytase showed a higher response when compared to the lower levels of supplementation.