Estimation of iron requirement for broiler breeder hens at the late stage of production cycle using nonlinear models

No study has been conducted on iron requirements of broiler breeder hens until now. The purpose of the present study was to determine the iron requirement of broiler breeder hens using nonlinear models. Forty eight (Cobb 500) broiler breeder hens were individually placed in galvanized wire cages. In order to depletion of hens iron reserved, hens were offered a semi purified iron deficient diet for 3 weeks. At 62 week of age, Hens were randomly allocated to 4 dietary treatments (37, 52, 67, 82 ppm of diet iron) with 4 replicates. Body weight gain, egg production and egg weight were measured during 6 weeks experimental period. The results showed that the estimated iron requirement for egg production(H.H), egg weight, iron content of the liver, blood serum, bone marrow, spleen and egg yolk were 65, 62, 54, 72, 57, 63, 64 ppm respectively. The logistic model was fitted to iron content of liver, spleen, serum and bone marrow, suggested that iron requirement were equal to 66, 53, 129, 58 ppm respectively. Fitted exponential model estimated iron requirement for egg weight, iron content of liver, spleen, serum and bone marrow were 62, 96, 70, 73, 111 ppm respectively. Also based on the quadratic equation models, estimated iron requirement for egg production(H.H), egg weight, iron content of the liver, blood serum, bone marrow, spleen and egg yolk were 65, 66, 71, 220, 51, 70, 62 ppm respectively. Among the four models used, the broken line model is more accurate in estimating the required iron than other models due to the low variance between estimated requirements. Results indicated that value recommended by primary breeder (Cobb 500 management guide, 55 ppm) is lower than values obtained in present study.