Evaluation of a stress model induced by dietary corticosterone supplementation in broiler breeders: effects on egg yolk corticosterone concentration and biochemical blood parameters

Abstract

1. This study aimed to evaluate a stress model induced by corticosterone (CORT) supplementation in the diet of broiler breeder hens.

2. A total of 60 Ross broiler breeder hens at 29 weeks of age were randomly divided into 4 groups with 15 hens each. The first group served as the control. The rest of the hens were given 1, 1.5 or 2 mg of CORT/hen/d (CORT₁, CORT_1.5 and CORT₂, respectively) for 7 d. Concentrations of yolk CORT, plasma uric acid, glucose, cholesterol, creatine kinase, heterophil (H):lymphocyte (L) ratio and duration of tonic immobility (TI) were measured at d 3, 5 and 7 of CORT supplementation. The same measurements were repeated at 3, 5 and 7 d after CORT was withdrawn from the diet.

3. There were no significant CORT dose effect on yolk CORT and plasma glucose concentrations. Higher plasma uric acid and H:L ratio was obtained for CORT_1.5 and CORT₂ than for CORT₁. From 3 to 7 d of dietary CORT supplementation, yolk CORT and plasma uric acid concentrations and H:L ratio increased whereas plasma glucose concentration decreased. After CORT was withdrawn from the diet, the H:L ratio remained elevated. The duration of TI and plasma creatine kinase concentration did not change during and after CORT supplementation.

4. Yolk CORT concentration was correlated with plasma uric acid concentration during CORT supplementation.

5. The results suggest that dietary CORT supplementation could be used as a stress model and to evaluate hormone-mediated maternal effects in broiler breeder hens.

ACKNOWLEDGEMENTS

This research was supported by Yüzüncü Yil University Scientific Research Projects (Project no: 2007-FBE-D93). This study is a part of the PhD thesis of the first author.