Effect of residual methane emission on physiological characteristics and carcass performance in Japanese Black cattle

This study investigated the physiological characteristics and carcass performance associated with residual methane emissions (RME), and the effects of bull differences on CH₄-related traits in Japanese Black cattle. Enteric methane (CH₄) emissions from 156 Japanese Black cattle (111 heifers and 45 steers) were measured during early fattening using the sniffer method. Various physiological parameters were investigated to clarify the physiological traits between the high, middle, and low RME groups. CH₄-related traits were examined to determine whether bull differences affected progeny CH₄ emissions. Ruminal butyrate and NH₃ concentrations were significantly higher in the high-RME group than in the low-RME group, whereas the propionate content was significantly higher in the low-RME group. Blood urea nitrogen, β-hydroxybutyric acid, and insulin concentrations were significantly higher, and blood amino acids were lower in the high-RME group than in the other groups. No significant differences were observed in the carcass traits and beef fat composition between RME groups. CH₄-related traits were significantly different among bull herds. Our results show that CH₄-related traits are heritable, wherein bull differences affect progeny CH₄ production capability, and that the above-mentioned rumen fermentations and blood metabolites could be used to evaluate enteric methanogenesis in Japanese Black cattle.