Comparative Studies on Metabolic Rate and Calpain/Calpastatin Activity between Hanwoo and Holstein Beef

The objectives of this study were to examine the effect of early short-term temperature conditioning on metabolic rate and calpain/calpastatin system and to compare variations in metabolic rate and calpain/calpastatin system between Hanwoo and Holstein beef. Longissimus thoracis et lumborum of the right carcass from 3 Hanwoo and 3 Holstein bulls were removed within 30 min of exsanguinations, cut into three pieces, and then temperature conditioned until 3 h postmortem (PM) at 2, 16, and $30^{\circ}C$, respectively. Rigor values (R-values; $R_248$, $R_250$, and $R_258$), pH, muscle temperature, glycogen content, $\mu$- and m-calpain activities, and calpastatin acitivity were measured at 1, 3, 9, and 24 h PM, respectively. Hanwoo beef had higher muscle temperature, faster metabolic rate at early PM stage in R-values, and lower $\mu$-calpain activity than Holstein beef (p<0.05). The $30^{\circ}C$ treatment maintained muscle temperature of $30^{\circ}C$ until 3 h PM and resulted in faster pH decline at 3 and 9 h PM (p<0.05) than other treatments. The $16^{\circ}C$ had higher (p<0.05) muscle temperature at 3 h PM than the $2^{\circ}C$, but no difference in all other traits was observed between the $2^{\circ}C$ and the $16^{\circ}C$. Early shortterm temperature treatment used in this study was not sufficient to effectively activate calpain/calpastatin system. Correlations among all traits except m-calpain and muscle temperature were generally high (r>0.60; p<0.001). Among R-values, $R_258$ had higher correlations with other metabolic traits than those of $R_248$ and $R_250$. These data suggest that early PM metabolic rate, $\mu$-calpain activity, and calpastatin activity may be closely related to each other. Variations in metabolic rate and $\mu$-calpain activity at early PM stage between Hanwoo and Holstein beef may imply variations in meat quality between both breeds.