Is Dietary Zinc Requirement of Broiler Breeder Hens at the Late Stage of Production Cycle Influenced by Phytase Supplementation?

This experiment was conducted to determine whether ۶-phytase has a positive effect on zinc requirements, production performance, and zinc content of tissues in broiler breeders at the end of their production cycle. One hundred and twenty-eight obese Cobb-۵۰۰ broiler breeder hens (>v۴.۹ kg) were weighed at ۵۸ weeks of age and assigned to various treatment groups. To deplete the zinc reserves in hens, they were given a zinc-deficient diet (۹.۵ mg kg-۱ of zinc) and drank water with ۳۵ μg L-۱ zinc for two weeks. Then, hens were randomly allocated to ۸ dietary treatments in a factorial arrangement of two levels of phytase (۰, ۳۰۰ FTU kg-۱) and four levels of dietary zinc (۳۰, ۶۰, ۹۰, ۱۲۰ mg kg-۱) with four replicates of ۴ hens in each. Bodyweight, egg production, egg weight, and egg quality were measured during the five-week experimental period. Added zinc significantly increased yolk weight and zinc content of yolk (P< ۰.۰۵) and plasma (P< ۰.۰۰۰۱). Egg weight was significantly increased by adding phytase (P< ۰.۰۵). As the results of this experiment show, adding exogenous phytase can decrease the zinc requirement of broiler breeder hens by releasing ۱۶.۹% of the zinc bound to phytate.

کلیدواژه ها:

Dietary zinc ، Exogenous phytase ، Nonlinear models ، Zinc bound to phytate.