title: The efficacy of adding a minimum adjusted fat thickness requirement to the USDA beef quality grading standards for select grade beef.
abstract: The present analysis was conducted to test the efficacy of adding a minimum 5-mm adjusted s.c. fat thickness requirement to the present USDA beef quality grading standards for the Select grade. Carcass grade data and longissimus thoracis Warner-Bratzler shear force and trained sensory panel ratings were analyzed for calf-fed steers (n = 1,602). The experimental group (nine breeds and three composite populations finished on medium- and high-energy diets) contained a large amount of variation 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 carcasses 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 > or = 5 mm s.c. fat thickness. However, the magnitude of those differences was so small that the current and proposed 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 rated "slightly tender" or higher for overall tenderness (48.7 vs 52.0). Thus, it seems that the addition of a minimum fat thickness requirement to the standards for the Select grade would not improve the tenderness of Select grade longissimus thoracis steaks.
authors.affiliation: Roman L. Hruska U.S. Meat Animal Research Center, ARS, Clay Center, NE 68933-0166.
authors.forename: S D
authors.initials: SD
authors.lastname: Shackelford
authors.forename: M
authors.initials: M
authors.lastname: Koohmaraie
authors.forename: T L
authors.initials: TL
authors.lastname: Wheeler
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology*; D000704:Analysis of Variance; D000818:Animals; D001947:Breeding; D002417:Cattle; D008297:Male; D008460:Meat / Q000592:standards*; D009132:Muscles / Q000033:anatomy & histology*; D012820:Silage; D014481:United States; D016885:United States Department of Agriculture