Effects of phytase supplementation on broiler chickens fed nutrient-deficient diets

Abstract

This study aimed to evaluate the effects of different inclusion levels of phytase on the performance, body composition, blood parameters, and bone characteristics of broilers fed reduced-nutrient diets. The experiment was conducted using 1400 male broilers, allocated to seven treatments with ten replicates and twenty birds per experimental unit, in a completely randomized design. The experimental treatments were: positive control, formulated to fully meet the birds’ nutritional requirements; negative control 1 (NC1), negative control 2 (NC2) and negative control 3 (NC3), formulated with nutrient reductions according to the phytase nutrient release matrix but without enzyme supplementation; and NC1, NC2 and NC3 supplemented with 500, 750 and 1000 FTU of phytase. Phytase supplementation improved (P < 0.05) body weight gain, feed conversion ratio, and final body weight compared to the negative controls, restoring these parameters to levels comparable with the positive control, even in diets simultaneously reduced in available phosphorus (P), total calcium (Ca), total sodium, metabolizable energy, crude protein, and digestible amino acids. Improvements were also observed in serum Ca and P levels, as well as in bone indicators, including the Seedor index, bone breaking strength, and ash and magnesium concentrations, matching those of the positive control (P < 0.05). Phytase supplementation further enhanced body composition, with greater deposition of lean tissue, protein, and bone in supplemented birds (P < 0.05). The main contribution of this study is the confirmation of phytase’s effectiveness as a nutritional tool in challenging diets, demonstrating its capacity to recover performance and bone quality, with benefits that extend beyond phosphorus utilization.