Optimization of Dietary Zinc Requirement for Broiler Breeder Hens of Chinese Yellow-Feathered Chicken

This study aimed to establish the optimal dietary zinc requirement of Chinese yellow-feathered Lingnan broiler breeders. A total of 576 breeder hens aged 58 weeks were randomly assigned to six treatments, each with 6 replicates of 16 birds (n = 96/treatment). The hens were fed either a basal diet (22.81 mg/kg Zn) or the same basal diet supplemented with additional 24, 48, 72, 96, and 120 mg Zn/kg up to 65 weeks of age. Compared to the results of birds fed the basal diet (22.81 mg Zn/kg), the dietary supplementation with additional Zn (mg/kg) showed higher egg laying rate (at 48–120 mg), EM (at 96 mg/kg), yolk Zn content (at 24–120 mg/kg), fertility (at 48–120 mg/kg), hatchability (at 48–96 mg/kg), tibial breaking strength (at 24–48 mg/kg), tibial ash content (at 48 mg/kg), serum CuZnSOD activity (at 72 mg/kg) and T-AOC (at 48 mg/kg), and ovarian CuZnSOD and GSH-Px activities (at 96–120 mg/kg), and lower FCR (at 96 mg/kg). The regression model showed that the optimal supplemental Zn for maximal egg laying rate, yolk Zn content, fertility, and hatchability of Chinese yellow-feathered broiler breeders aged 58 to 65 weeks were 71.09, 92.34, 94.44 and 98.65 mg/kg diet, respectively.