A proposal of Carcass Grading System for Cull Cows Using Principal Component Analysis

A total of 55 carcasses of cull cows between 6 and 13 old years were evaluated for conformation and fatness in the objective to develop a carcass grading standard using morphometric measurements. The slaughtered cull cows are mainly Holstein. Carcass measurements performed at the slaughterhouse were: length of the carcass, perimeter of the hind leg, depth of the carcass, length and thickness of the hind leg. Hot carcass weight, thickness of fat cover at the sixth rib and kidney fat weight were recorded. Carcass characterization was performed using principal component analysis and cluster. Correlations were determined among the carcass measurements. Analysis of variance was also performed to determine significant difference between the three classes of carcasses found in this study (P<0.05). Our results showed the existence of three groups of carcass defined as following: Carcasses with a low conformation and a small frame size, Carcasses with an average conformation and a medium frame size and Carcasses with a fairly good conformation and a large frame size. This study provides a basis for a carcass classification grid using quantitative measurements that meets the needs of butchers and meat processors to balance price grade of marketed carcasses.