High levels of dietary phytase improves broiler performance

Abstract The objective of this study was to evaluate the effects of dietary phytase on broilers from 1 to 42 days of age. Five treatments were distributed in a completely randomized design, with eight replicates of 23 birds per experimental unit (per averages). The treatments consisted of a positive control diet (PC), a negative control diet (NC); and the NC diet + 1000, 2000 and 3000 FYT kg −1 phytase. The effects of dietary treatments on performance, bone quality and blood minerals were determined. From 1 to 21 days of age, WG, FI and FCR increased with increasing levels of phytase (P  −1 (P  −1 , respectively. At 42 days of age, the Seedor Index (SI) and bone-dry matter (DM) were maximized at lower levels of phytase than for WG or FCR. The highest SI and DM values were obtained with 1553 and 1765 FTY kg −1 , respectively. At 21 days of age, blood Ca content decreased with increasing phytase levels. Blood P exhibited quadratic behavior, with the maximum recorded at 1680 FYT kg −1 phytase. Tibia Ca increased with increasing phytase at 21 days of age (P  −1 phytase, respectively. It is concluded that phytase improves broiler performance based on regression analyses. A high dose of 2973 FYT kg −1 had the best weight gain from 1 to 21 days of age. From 21 to 42 days, 2051 FYT kg −1 and 2101 FYT kg −1 showed the best weight gain and feed conversion ratio, respectively. These recommendations did not negatively affect the parameters evaluated.