Optimizing slaughter age to balance methane emission intensity, carcass performance, and meat quality in Hanwoo steers

Objective: This study evaluated whether reducing slaughter age in Hanwoo steers could decrease enteric methane emission intensity while maintaining carcass performance and meat quality. Methods: Of 48 steers originally assigned to slaughter at 26, 28, or 30 months (16 per treatment), 33 animals with complete matched carcass and methane-emission records were included in the present animal-level analysis (26M, n = 12; 28M, n = 8; 30M, n = 13). Feed intake and enteric methane emissions were individually measured using a GreenFeed system. Carcass characteristics and meat qualities were evaluated. Results: Slaughter age did not affect daily dry matter intake, daily methane production, or methane yield per unit of feed intake (p > 0.05). Final body weight, carcass weight, and meat yield were numerically higher in the 28M and 30M groups than in the 26M group but did not differ significantly among groups. Extending slaughter age from 28 to 30 months resulted in a 10.5% increase in methane emission intensity per kilogram of meat yield, from 9.37 to 10.35 kg CO2-eq/kg meat yield. Older slaughter ages also increased fat content, water-holding capacity, and tenderness, as indicated by lower shear force (p < 0.05). Flavor-related amino acids increased with slaughter age. However, improvements in carcass and meat quality were relatively limited from 28 to 30 months, whereas methane emission intensity increased more markedly. Conclusion: Slaughtering Hanwoo steers at approximately 28 months may provide a favorable 48 balance between carcass performance, meat quality, and enteric methane emission intensity.