Comparative transcriptomic and meat quality responses to electrical and controlled atmosphere stunning in broiler chickens

In the poultry industry, the slaughter process poses significant animal welfare concerns due to the substantial stress it induces in broilers. Electrical stunning (ES) and controlled atmosphere stunning (CAS) are commonly used methods to render broilers unconscious before slaughter, but both have welfare implications. This study compares ES and CAS by analyzing stress-related gene expression profiles using RNA sequencing (RNA-seq) and evaluating meat quality parameters. The results reveal distinct molecular responses to each method. Meat quality analysis shows that ES leads to higher redness and fat content, while CAS results in greater moisture content. ES induces physiological stress by causing tissue damage and activating inflammatory pathways, whereas CAS does so through hypercapnia and immune response downregulation, suggesting lower oxidative stress and reduced physiological burden. Future studies should integrate behavioral and neurophysiological assessments, tissue-specific histology, biochemical markers, and comparative evaluations of inert-gas stunning methods (e.g., argon, nitrogen) to better contextualize welfare implications. These findings provide new insights into the molecular and physiological impacts of stunning methods, contributing to the development of more humane poultry production practices.