Energy releasing efficacy of graded levels of a commercial microbial phytase

SUMMARY An experiment was conducted to determine the energy release of a commercial phytase fed to broilers at multiple doses in basal diets that varied in ME. Dietary treatments included three negative controls (NC; 0.75% calcium and 0.30% non-phytate phosphorus) formulated at three ME levels (2701, 2868, and 3000 kcal/kg). A commercial phytase product was added to each NC diet at 1500, 4500, 13500, and 30000 FTU/kg, creating a total of 15 dietary treatments. The phytase utilized was a phytase sourced from an Escherichia coli species bacterium expressed in a Trichoderma reesei fungus. Treatments were arranged in a 5 (phytase dose) x 3 (ME level) factorial in a randomized complete block design with nine replications of ten male broilers fed each of 15 dietary treatments for 21 days. On d7, 14, and 21, birds provided the 3000 kcal/kg diet had the lowest bird FI, and birds provided the 2701 and 2868 kcal/kg diets had the highest (P