Alteration of stress response and expression of carbohydrate metabolic genes by exogenous insulin during slaughter of domestic birds

Aim: This study investigates the novel role of exogenous insulin in modulating stress responses in domestic birds during slaughter. The research explores insulin’s potential in reducing stress markers and its effects on gene expression related to glucose transport and insulin regulation. Methods: A total of 45 birds, including broiler chickens, Sonali chickens, and quails, were divided into three treatment groups. They received either 4 IU or 8 IU of insulin, or phosphate-buffered saline (PBS) as a control. Thirty minutes after administration, blood, liver, and pancreas samples were collected for analysis. Stress markers such as the heterophil-to-lymphocyte (H:L) ratio and serum cortisol levels were measured, along with the expression of key genes, including GLUT12, insulin receptor (IR), and insulin (INS). Results: Insulin administration significantly reduced the H:L ratio across all bird species, indicating a stress-reducing effect. While cortisol levels decreased in Sonali chickens, broilers exhibited an unexpected rise in cortisol at lower insulin doses, suggesting species-specific variations. Additionally, insulin upregulated GLUT12 gene expression in both the liver and pancreas, enhancing glucose transport. Increased IR expression was observed in the liver, and insulin administration stimulated its own transcript (INS) in the pancreas, suggesting a self-regulatory mechanism. Conclusion: These findings highlight insulin's potential in mitigating slaughter-induced stress in poultry. Its effects on cortisol regulation and GLUT12 expression suggest a broader physiological role beyond glucose metabolism. Incorporating insulin-based interventions could offer new strategies for improving animal welfare in the poultry industry.