A meta-analysis of broiler chicken meat quality: Comparative evidence of halal slaughter and electrical stunning

Pre-slaughter handling and slaughter practices are crucial in determining broiler chicken meat's quality and market value. Despite the widespread adoption of stunning in commercial poultry production, its influence on meat quality remains contentious, particularly from the perspective of consumer preference and halal compliance. This meta-analysis quantitatively evaluated the effects of electrical stunning and halal slaughter on the meat quality of broiler chickens. Studies published between 2010 and 2024 were systematically searched across five databases. Eight of the 1,018 identified studies met the inclusion criteria and were subjected to meta-analysis. Standardized mean difference (SMD) and corresponding 95% CI were calculated using a random effects model. Detected heterogeneity was assessed by subgroup and meta-regression analyses. The meta-analysis revealed that electrical stunning significantly improved early pH (≤4 h), ultimate pH (24 h), water holding capacity (WHC), yellowness, and fat content, while halal slaughter resulted in higher redness. Among strains, Cobb 500 showed greater responsiveness in early pH, WHC, and yellowness, suggesting genetic influence on stunning tolerance. Water bath electrical stunning (WBES) significantly increased early pH, indicating more stable postmortem metabolism. Lower electrical current intensity significantly increased early pH, ultimate pH, and yellowness of broiler breast muscle. Furthermore, longer stunning durations were positively correlated with higher early pH (Estimate = 1.5959; R² = 82.65), and fat content (Estimate = 0.6284; R² = 91.73), but decreased redness (Estimate = -0.2871; R² = 30.74). Slaughter age explained all between-study variation observed in yellowness (Estimate = 0.1581; R² = 100%), with older birds producing more yellowish meat due to increased fat deposition. In summary, electrical stunning effectively enhanced key meat quality traits in broiler breast muscle; however, its impact is moderated by strain, stunning method, electrical current intensity, slaughter age, and stunning duration. This provides useful guidance on the application of electrical stunning on commercial broiler chickens for improved meat quality and increased consumer acceptability.