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Comparisons of meat palatability between bulls and steers have indicated that meat from young bulls is more variable in tenderness. In addition, meat from bulls is usually numerically less tender, although the difference is frequently not statistically significant. This indicates that meat from bulls is only slightly, but consistently less tender than meat from steers.
Numerous studies have attempted to link bull meat toughness to higher amounts and decreased solubility of connective tissue. However, it has been reported that this change in bull meat does not occur until 12 to 16 mo of age. It has been shown conclusively, using different species and a variety of conditions, that the calpain enzyme system (which occurs naturally in muscle) is responsible for a majority of the tenderization that occurs during aging of meat. The possible contribution of the calpain system to differences in postmortem tenderization of muscle from bulls and steers has not been reported. This study was conducted to examine the effect of castration on palatability traits and 24-hr postmortem activities of μ-calpain, m-calpain and calpastatin in loin muscle of cattle.