RELATIONSHIP OF BODY-COMPOSITION OF MATURE EWES WITH CONDITION SCORE AND BODY-WEIGHT

Fourteen mature, ovariectomized, western-range ewes with an initial mean BW of 72 +/- 4.5 kg and mean condition score (CS) of 7.5 +/- .3 were used to evaluate the relationship between CS and body composition. Diets of chopped straw and alfalfa hay were formulated to provide either maintenance energy or less than maintenance energy (100 or 60% of ME) to induce changes in BW and CS. After 180 d, ewes were weighed, scored for body condition, and slaughtered. All carcass components, viscera, and organs were analyzed for lipid, DM, and ash, and protein was determined by difference. Body weight and CS values were related by regression analysis to percentage of composition and weights of carcass components, carcass, and empty body. Body weight and CS were highly correlated (r = .89) and analysis indicated that each increase in CS resulted in an increase of 5.1 kg of BW. Condition score accounted for more variation of percentage of lipid in the empty body (R2 = .95) and carcass (R2 = .90) than did BW (R2 = .84 and .80, respectively). In contrast, BW accounted for more of the variation in carcass weight (R2 = .97) and empty BW (R2 = .99). Inclusion of both BW and CS in regression models did not increase the variation accounted for with the single best predictor. With mature western-range ewes in this study, CS was highly related to carcass lipids and could be used to describe energy reserves available to ewes.