147 Calpastatin Isoforms Related to Meat Tenderness in Beef Cattle.

Tenderness and consistency are continuing challenges in beef products. Calpastatin (CAST) is a protein that inhibits muscle degradation and post-mortem tenderization of meat. At the mRNA level, at least four specific CAST variants have been reported in cattle, but most quantification methods do not differentiate between the specific isoforms. This project measured three unique isoforms of CAST and correlated these isoforms to shear force tenderness in beef cattle. Fresh cheek muscle samples were collected on thirty commercial cattle immediately after harvest for relative gene expression analysis on CAST I, CAST II, and CAST IV isoforms by qPCR. Ribeye steaks were retained from each carcass, aged, cooked, and analyzed for shear force to measure tenderness. The levels of CAST isoforms were regressed on the tenderness measurement to determine the effect of the specific isomers on beef tenderness. After running a stepwise regression of shear force with an entry threshold of 0.25; CAST II, days aged and steak width were deemed significant enough to remain (0.15) in the model. The data concluded that 17.08% of the deviation in tenderness can be explained by the following formula: Continuing research could eventually assist breeders in producing consistently tender carcasses, and processors in screening tough and tender products for different uses.