Phytase Improves Zinc Utilization by Broiler Chickens

The study aimed to evaluate phytase effects on the availability of zinc (Zn) from corn and soybean meal feeds for broiler chickens, whereas, in parallel, Zn requirements were investigated. A total of 640 Cobb × Cobb 500 male chicks were fed a Zn-deficient diet (18.87 ± 0.87 mg/kg Zn) until 7 days of age. The experiment was a 2 × 5 factorial with 10 treatments (feeds with or without phytase × 5 increasing dietary Zn levels) with 8 replications of 8 birds each. Supplemental Zn sulfate heptahydrate was used (measurements of the Zn analyzed in the feeds were 30.1 ± 0.73, 61.6 ± 0.13, 90.4 ± 1.60, 123.6 ± 1.99, and 151.9 ± 1.84 mg/kg, respectively). There were no interactions between phytase and Zn for any evaluated response. Phytase improved broiler performance and increased plasma myo-inositol, Zn content in the liver and tibia, Zn retention, and digestible energy (p < 0.05). No significant impact of dietary Zn was found on broiler performance (p > 0.05) except for Zn excretion and tibia Zn content. Adding phytase at 4000 FYT increased the apparent ileal Zn digestibility by 98% and Zn retention by 13.7%, whereas Zn supplementation of up to 151.9 mg/kg did not impact broiler performance.