Stress-induced alterations in leukocyte profile and serum biochemical parameters in broilers

1. This study assessed the impact of varied stressors on blood leukocyte dynamics and biochemical parameters in broiler chickens. Sixty male broiler chickens (28-30 d old; 1.4-1.5 kg) were divided into four groups (A-D). Group A (control) was reared under optimal conditions. Group B underwent transport stress via a 2-h journey before slaughter. Group C was reared under high stocking density (SD) throughout the rearing period. Group D was exposed to heat stress (37 ± 2°C) for 4 h daily during rearing.2. Exposure to transport and heat stress resulted in a significant increase in circulating heterophils (H), a reduction in lymphocyte (L) counts, and a decrease in serum corticosterone concentrations (p < 0.01), thereby leading to a significantly elevated H:L ratio (p < 0.05). In contrast, serum levels of total protein, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatinine level remained unaffected under conditions of transport and stocking density stress.3. Heat stress increased ALT and creatinine while decreasing AST and serum total protein, and reduced triglycerides (TG) levels significantly (p < 0.05) without affecting low density lipoprotein cholesterol (LDL-c), high density lipoprotein cholesterol (HDL-c) or total cholesterol. In contrast, heat stress increased LDL-c, and total cholesterol (p < 0.05), with decreased HDL-c values.4. This study reveals the comparative effects of diverse stressors on blood leukocytes and biochemical parameters in broiler chickens. Understanding these physiological responses is crucial for enhancing poultry management strategies and promoting animal welfare in the context of commercial poultry production.