Iron requirements of broiler breeder hens.

A study was conducted to investigate Fe requirements of broiler breeders. One-hundred-fifty-six Cobb 500 broiler breeder hens were individually placed in electrostatically painted cages at 22 weeks. The study was composed of an adaptation phase, in which hens were fed corn-soy-wheat bran diets until 35 wks. An Fe deficient mash diet (24.6 ppm Fe) was provided from 35 to 46 wk in order to induce a partial body Fe depletion. A production phase followed from 47 to 70 wk when hens were fed 6 diets with increasing Fe sulfate supplementation, which, upon analyses had 24.6, 48.6, 74.3, 99.6, 125.6, and 148.2 ppm Fe. Thirty hatching eggs from each treatment were randomly collected in the last wk of each production period and incubated. Hemoglobin and hematocrit were analyzed from 6 hens as well as all hatched chicks per treatment. Analyses of production and hatching data were conducted using quadratic polynomial (QP), broken-line (BL), and exponential asymptotic (EA) models. Effects of dietary Fe were observed for total eggs and total hatching eggs, egg yolk Fe content, and hen and chick hematocrit and hemoglobin (P < 0.05). These responses to added Fe were optimized when dietary Fe were 96.8, 97.1, 130.6, 122.6, 120.0, and 125.0 ppm (QP) and 76.4, 89.3, 135.0, 128.4, 133.8, and 95.0 ppm (BL) for total hatching eggs, egg yolk Fe content, and hen and chick hematocrit and hemoglobin, respectively. Optimization with the EA model was obtained for total hatching eggs, egg yolk Fe, and hen and chick hemoglobin at 97.9, 111.0, 77.9, and 96.3 ppm Fe for total hatching eggs, egg yolk Fe, and hen and chick hemoglobin, respectively. Adequate Fe levels are needed to maintain egg production as well as hatching chicks' indexes. Fe concentration in the yolk and diet are positively influenced. The average of all Fe requirement estimates obtained in the present study was 106 ppm total Fe, whereas averaged values for BL, QP, and EA models were 107, 113, and 97 ppm Fe, respectively.