Calcium:phosphorus ratios and supplemental phytases on broiler performance and bone quality

This study aimed to evaluate 2 phytases, at 2 supplementation doses, in broiler diets with nutritional matrices with reduction in Ca:total P (tP) ratio. One-day-old male chicks (n = 3,960) were distributed in an arrangement of 12 treatments, with 10 replicates each; the experimental unit consisted of a floor pen with 33 birds each. Trial lasted up to 42 D, and birds were given the experimental diets: T1-positive control 1 (high Ca:tP ratio-recommended amount); T2-negative control 1 (reduction of 0.16% Ca and 0.16% available P-AP); T3-T2 + 500 FTU/kg enzyme A; T4-T2 + 500 FTU/kg enzyme B; T5-T2 + 1000 FTU/kg enzyme A; T6-T2 + 1000 FTU/kg enzyme B; T7-positive control 2 (low Ca:tP ratio); T8-negative control 2 (reduction of 0.16% Ca and 0.16% AP); T9-T8 + 500 FTU/kg enzyme A; T10-T8 + 500 FTU/kg enzyme B; T11-T8 + 1000 FTU/kg enzyme A; and T12-T8 + 1000 FTU/kg enzyme B. At 21 and 42 D of age, performance variables were recorded (body weight, body weight gain, feed intake, and feed conversion ratio) and tibial bone composition (Ca and P) and resistance was determined (strength at rupture). Results indicate that enzyme supplementation was efficient, regardless of Ca:tP ratio. The highest phytase dose presented superior results, especially for the 21-D evaluation. Phytase "B," a bacterial product, showed superior response on performance and bone quality.