Influence of body condition score on carcass characteristics and subprimalyield from cull beef cows

Mature beef cows (n = 83) were slaughtered to measure the influence of body condition score (BCS) on carcass characteristics and subprimal yields. All cows were weighed and assigned BCS, based on a 9-point scale, 24 h before slaughter. Cows were slaughtered, and, after a 48-h chilling period, qualit y and yield grade data were collected on the left side of each carcass. The right side was quartered, fabricated into primal cuts, and weighed. Each p rimal cut was further processed into boneless subprimal cuts, minor cuts, l ean trim, fat, and bone. Cuts were progressively trimmed to 6.4 and 0 mm of external and visible seam fat. Weights were recorded at all stages of fabr ication, and subprimal yields were calculated as a percentage of the chille d carcass weight. Live weight, carcass weight, dressing percentage, fat thi ckness, longissimus muscle area, muscle:bone ratio, and numerical yield gra de increased linearly (P = .0001) and predicted cutability and actual muscl e-to-fat ratio decreased linearly (P =.0001) as BCS increased from 2 to 8. Carcasses from BCS-8 cows had the most (P < .05) marbling. The percentage o f carcasses grading U.S. Utility, or higher, was 16.7, 20.0, 63.6, 43.3, 73 .3, 100.0, and 100.0% for cows assigned a BCS of 2, 3, 4, 5, 6, 7, and 8, r espectively. At 6.4 mm of fat trim, carcasses from BCS-5 cows had higher (P < .05) shoulder clod yields than carcasses from cows having a BCS of 6, 7, and 8. Carcasses of BCS-2 cows had lower (P < .05) strip loin yields than carcasses from BCS-3, 4, 5, 6, and 7 cows. Top sirloin butt yields were hig her (P < .05) for carcasses of BCS-8, 3, 4, and 5 cows than those of BCS-B, 7, or 8 cows. Carcasses from BCS-7 and 8 cows had lower (P < .05) tenderlo in and inside round yields than carcasses of BCS-5, or less, cows. At both fat-trim levels, carcasses from BCS-5 cows had higher (P < .05) eye of roun d yields than cows assigned BCS of 2, 7, or 8. When subprimal cuts were tri mmed to 6.4 mm of visible fat, carcasses from BCS-5 cows had higher (P < .0 5) total lean product yields than cows assigned a BCS of 2, 4, 7, and 8. Re gardless of fat trim, total fat yields increased (P =.0001) and total bone yields decreased (P =.0001) linearly as BCS increased from 2 to 8. Although carcasses from BCS-5 and 6 cows had the highest yields of lean product, ca ttle producers and packers may benefit most by marketing and(or) purchasing BCS-B cows because a higher percentage of their carcasses had quality char acteristics deemed desirable for fabrication into boneless subprimal cuts.