Is Dietary Zinc Requirement of Broiler Breeder Hens at the Late Stage of Production Cycle Influenced by Phytase Supplementation?
نویسندگان
1 Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Islamic Republic of Iran.
2 Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Islamic Republic of Iran.
3 Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Islamic Republic of Iran.
4 Department of Animal & Poultry Nutrition, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Islamic Republic of Iran.
doi
10.22034/JAST.26.6.1275چکیده
This experiment was conducted to determine whether 6-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-500 broiler breeder hens (>v4.9 kg) were weighed at 58 weeks of age and assigned to various treatment groups. To deplete the zinc reserves in hens, they were given a zinc-deficient diet (9.5 mg kg-1 of zinc) and drank water with 35 μg L-1 zinc for two weeks. Then, hens were randomly allocated to 8 dietary treatments in a factorial arrangement of two levels of phytase (0, 300 FTU kg-1) and four levels of dietary zinc (30, 60, 90, 120 mg kg-1) with four replicates of 4 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< 0.05) and plasma (P< 0.0001). Egg weight was significantly increased by adding phytase (P< 0.05). As the results of this experiment show, adding exogenous phytase can decrease the zinc requirement of broiler breeder hens by releasing 16.9% of the zinc bound to phytate.
