Efficacy of three heat-stable microbial phytases on growth performance and bone development and strength of broilers fed diets deficient in available phosphorus

Abstract

A total of 2340 as-hatched Cobb500 chicks were allocated to 9 treatments, each with 13 replicate pens to evaluate the effects of either three phytase enzymes in a P-deficient diet. Starter and finisher diets consisted of a positive control (PC) and negative control 1 and 2 (NC1 and NC2, respectively). The PC, NC1, and NC2 diets had Ca:avP (available phosphorus) ratios of 0.50, 0.33, and 0.43 in the starter feed, and 0.46, 0.22, and 0.35 in the finisher feed, respectively; NC1 diets were then supplemented with Phytaverse, Quantum Blue, and Axtra-PHY at 500 and 1000 FTU/kg. Enzyme type had significant effects on body weight gain, feed conversion ratio, and production efficiency factor during the 0–7-day period. Interactions between enzyme type and inclusion levels had a significant effect on feed intake (FI) at 1–21-day ( P = 0.02) and 1–35-day ( P = 0.031) age. While FI decreased as Axtra-PHY inclusion levels increased from 500 to 1000 FTU/kg feed, FI increased in birds supplemented with Quantum Blue, but with no effects on Phytaverse-supplemented birds. Increasing the enzyme dose to 1000 FTU/kg feed improved bone-breaking strength but did not affect growth performance, tibia ash, Ca, or P concentration of the birds.