Effects of Dietary Treatment, Gender, and Implantation on Calpain/Calpastatin Activity and Meat Tenderness in Skeletal Muscle of Korean Native Cattle

The objectives of this study were to examine calpain activity and meat tenderness by three different feeding patterns in Korean native cattle (KNC). Total forty-five animals were assigned each fifteen in long term restriction feeding (LTFR), long-term restriction feeding and hormone treatment (LTFR-tH), and short term non-restriction feeding (STFNR), respectively. Concentrate was restricted based on body weight in exp 1 and 2. However, it was fed ad libitum in exp. 3. Hormonal implantation was made with $M-PO^{TM}$ for bulls and with $F-TO^{TM}$ for heifers at 18, 20, 22 months of age in exp. 2. Animals were purchased (3-5 month old) from local cattle market and managed in two local farms and university research unit at three different years. Animals were slaughtered at 24 months for long-term trial and at 18 month for short term-trial. Loin and tender loin muscle was used for calpain activity and meat quality. Calpain proteolytic system was not changed by treatment. However, calpastatin activity was low in short-term trial. The calpain and calpastatin activity is reciprocal relationship, therefore, the high calpain activity may effect on quality grade. The shear force value was decreased as the processing of aging after postmortem. On the other hand, the cooking loss was significantly higher in short-term than in long-term trial, and then gradually decreased by the aging. Hormone implants to increase meat yield influenced to calpastatin activity more powerfully than calpain activity to meat tenderness. In meat color-a*, there was not significant difference in loin. Meat color-b* was decreased as postmortem aging time increased in tenderloin. Western blots were done to learn whether these proteins are degraded during postmortem storage and whether this degradation temporally parallels the decrease of shear force value. Vinculin was detected at 0 day and 1 day and degraded after 3 day. In conclusion, Calpain activity was affected slightly on meat tenderness. But meat tenderness was influenced by calpastatin, more effectively.