Abstract
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.