Tenderness Studies in Straightbred and Crossbred Steers

Two-hundred and sixty straightbred and crossbred steers of Angus, Brahman, Hereford and Charolais breeding were utilized for tenderness studies. The data indicated that less tender steaks were from lower grading carcasses with smaller longissimus muscle area at the 12th rib. Less tender muscle had lower 1-hr temperatures, higher 6-day pH measurements and shorter sarcomere lengths than more tender muscle. Although the absolute differences in pH values were small, the results suggest that measurement of postmortem pH might offer a practical means of segregating carcasses into tenderness groups. A multiple regression analysis to predict Warner-Bratzler shear (WBS) revealed that the optimum equation was: WBS = 98.91 + 26.29 (6-day pH) - .81 (U.S.D.A. quality grade) − 13.41 (fat thickness, cm) − 9.55 (longissimus area, cm2). A separate analysis revealed that breed effects did not additionally contribute to the variation in WBS. Armour Tenderometer values did not predict carcass tenderness as measured by the WBS, but higher marbling scores were associated with increased penetration resistance.