Characterization of Canadian grade standards and lean yield prediction for cows

摘要

Commercial cattle carcasses (n = 120) were selected to benchmark the current Canadian grading system for cows (D1, D2, D3, D4; >50% ossification) in comparison to A/AA grades youthful carcasses (over (OTM) and under (UTM) 30 mo of age based on dentition but <50% ossification). With the exception of the D3 and D4 grades, D1 and D2 carcass grades had similar carcass yield attributes compared with OTM and UTM carcasses; however, rib-eye area from UTM carcasses was the largest (P < 0.05), followed by D1, D2 and OTM. As expected, both OTM and UTM grades had lower ossification scores (P < 0.05); however, D4 grade showed the highest marbling score (P < 0.05). For carcass composition, compared with all other grades, the D3 grade had the highest proportion of lean (P < 0.05) due to a lower proportion of dissectible fat (P < 0.05); however, it had the lightest carcass weight (P < 0.05). Using simple measures of carcass characteristics (grade fat, rib-eye area, marbling and ossification) a prediction equation to estimate lean yield (R2 = 0.825; Cp = 4.31) could be used to more accurately assess carcass value in cows; however, validation of the equation on a separate population would be required before its application.