Is dietary iron requirement of broiler breeder hens at the late stage of production cycle influenced by phytase supplementation?

Abstract

The purpose of this study was to investigate the effects of phytase on iron requirement of broiler breeder hens at the late stage of production cycle. Ninety-six Cobb (500) broiler breeder hens were weighed and individually placed in galvanized wire cages at 59 weeks of age. In order to depletion of hens iron reserved, after placement, hens were offered a semi-purified iron-deficient (37 mg iron/kg) diet for three weeks. At 62 weeks of age, hens were randomly allocated to eight dietary treatments in a factorial arrangement with four replicates of three hens in each. Factors included two levels of phytase (0 and 600 U/kg) and four levels of iron (37, 52, 67 and 82 mg/kg). Hens were fed the experimental diets from 62 to 68 weeks of age. Iron in the diet had significant effects on egg weight (P < 0.05). Increasing dietary iron content significantly increased the concentration of iron in the bone marrow, liver, spleen (P < 0.05), egg yolk and blood serum (P < 0.01). Added phytase enhanced the iron concentration of the egg yolk and serum (P < 0.01). It seems that phytase can release iron from inositol in old broiler breeder hens and increased chicken iron reserve. Two slope, broken-line analysis of hen house egg production regressed on the dietary added iron indicated that 65 mg/kg supplemental iron without phytase and 58 mg/kg supplemental iron with phytase were required for the optimal egg production of broiler hens.