EFFICACY OF ADDING A MINIMUM ADJUSTED FAT THICKNESS REQUIREMENT TO THE USDA BEEF QUALITY GRADING STANDARDS FOR SELECT GRADE BEEF

The present analysis was conducted to test the efficacy of adding a mi nimum 5-mm adjusted s.c. fat thickness requirement to the present USDA beef quality grading standards for the Select grade. Carcass grade da ta and longissimus thoracis Warner-Bratzler shear force and trained se nsory panel ratings were analyzed for calf-fed steers (n = 1,602). The experimental group (nine breeds and three composite populations finis hed on medium- and high energy diets) contained a large amount of vari ation in yield grade, marbling score, Warner-Bratzler shear force, and sensory panel overall tenderness ratings (CV = 30.8, 17.9, 25.0, and 14.0%, respectively). All but one of the carcasses were of A maturity and 37% of the carcasses had < 5 mm adjusted fat thickness. Among carc asses with a ''slight'' amount of marbling, WBS values were higher (5. 58 vs 5.32 kg; P < .01) and overall tenderness (4.82 vs 4.99; P < .01) was lower for carcasses with < 5 mm s.c. fat thickness than for those with greater than or equal to 5 mm s.c. fat thickness. However, the m agnitude of those differences was so small that the current and propos ed Select grades did not differ with respect to shear force (5.45 vs 5 .32 kg), overall tenderness (4.90 vs 4.99), juiciness (5.09 vs 5.12), beef flavor intensity (4.86 vs 4.86), or the percentage of samples rat ed ''slightly tender'' or higher for overall tenderness (48.7 vs 52.0) . Thus, it seems that the addition of a minimum fat thickness requirem ent td the standards for the Select grade would not: improve the tende rness of Select grade longissimus thoracis steaks.