Evaluation of feedlot cattle working chute behavior relative to temperament, tenderness, and postmortem proteolysis.

The objective was to investigate if the association between working chute behavior and beef tenderness found in our previous study is related to protein degradation and calpain system activity. Crossbred steers (n=183) allotted to 16 pens were weighed every 28 d. Temperament was evaluated as exit velocity (EV), chute score (CS), and catch score (CAPS). Between 14 and 16 mo of age (606±52 kg), steers were harvested. Strip steaks were collected and aged for 14 d. Subsamples were collected at 36 h and 7d postmortem and analyzed for calpastatin activity, μ-calpain autolysis, and troponin-T degradation. Shear force (WBSF) was correlated (P<0.05) with calpastatin activity and measurements of troponin-T. Calpastatin activity, μ-calpain autolysis, and troponin-T measurements did not correlate with the measurements of EV, CS, and CAPS. Therefore, activation of the calpain system or differences in protein degradation did not appear to influence the differences in tenderness that are correlated with working chute behavior.