Effect of adrenal blocking chemicals on the responses of chickens and turkeys to environmental stressors and ACTH

Abstract

An adrenal blocker, 1,1dichloro‐2,2‐bis/p‐chlorophenyl/ethane, was most effective when given intramuscularly, at a dose rate of 16 or 14 mg/kg of body weight, the technical or reagent chemical, respectively (P<0.001). The optimal dose for meryrapone was 500 mg/kg feed. Following exposure to a variety of Stressors treated chickens and turkeys had heterophil/lymphocyte ratios which were lower than those of the uninjected controls. The optimal doses were effective over a wide range of body weights (0.35 to 5.2 kg). Blocking began within 12 h after injection and lasted for at least 77 days. Repeated doses were not additive. Blockers did not suppress body weight gain. The magnitude of the blocking effect increased with increasing H/L ratios among the controls and was ineffective in unstressed chickens.