Physiological Adaptation and Stress Dynamics in Indigenous Chickens Following Transition from Natural to Intensive Rearing System: A Longitudinal Hematological, Biochemical, and Hepatic Biomarker Study

Abstract

In this study, the physiological adaptation and stress reaction of Iraqi indigenous chickens was assessed after the change from natural rearing system to intensive rearing system, related to the connection between housing system and health-status biomarkers. Twenty-five hundred birds were used, divided into five experimental replicates, and analyzed periodically for complete blood count (CBC) and blood glucose, lipids and liver enzymes, and specific stress indicators. The results showed that the conversion to the intensive system resulted in significant and clear changes: the RBC count decreased by 3.2×106/µL to 2.6×106/µL and the level of hemoglobin (Hb) went down from 12.5g/dL to 10.0g/dL. In contrast, there were consistent elevations in blood glucose (from 180 to 265 g/dL) and triglycerides (from 83 to 143 g/dL) while white blood cell (WBC) counts rose consistently from 20 to 32 ×103/µL. In addition, there was a noticeable metabolic stress load on the liver reflected by a significant increase in the H/L ratio (1.07) and a decrease in the A/G ratio (1.5 to 1.0), suggesting a shift in protein balance towards immune activity to deal with the rearing conditions. The overall results indicate that indigenous chickens are at risk of experiencing real physiological and metabolic stress due to intensive rearing systems, and require careful management of their hormonal status and productivity.