Effect of Graded Levels of an Enhanced E coli Phytase with Step-Wise Reduction of Supplemental Inorganic Phosphate on Growth Performance of Broilers Fed Corn-Soy Diet
Poernama, FWibowo, T. AGomes, G. AAftab, U
This study evaluated the potential of incremental doses of an enhanced Escherichia coli-derived phytase to support step-wise reduction of supplemental inorganic phosphate in an all-vegetable broiler diet. Corn-soybean meal-based diets containing 0.40/0.80%, 0.35/0.70%, and 0.30/0.60% avP and Ca, respectively from 0-10, 10-25, and 26-42 days posthatch served as experimental control (PC). Three test diets were formulated with 500, 1000, and 1500 FTU/kg of phytase assigned respectively an avP matrix of 0.15, 0.19, and 0.23% and a fixed Ca matrix of 0.15%. An additional diet (PC++) containing extra avP and Ca (+0.05% avP/+0.1% Ca) to that of PC was included to test if avP and Ca were not limiting in PC. Each diet was offered to 16 replicates of straight-run broilers kept in floor pens (30 birds per pen). PC++ had lower (p 0.05; 10 and 25 d) or similar (42 d) BW and toe ash compared with PC confirming the avP and Ca set in PC were sufficient to support optimal growth and bone mineralization. Compared to the PC, diets containing 1000 and 1500 FTU phytase had higher BW (p 0.05) at 10 and 25 d. For the overall period of 0-42 d, FI, BW and FCR did not differ across treatments. Percentage-, but not the absolute-, toe ash at phytase treated groups was significantly (p 0.05) low compared with the PC. The experiment demonstrated that 1500 FTU/kg of enhance E. coli phytase supports optimal BW and FCR of broilers fed corn-soy diet largely void of supplemental inorganic phosphate.(AU)
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