Adjusting weight for body condition score in Angus cows.

Weight, height, and body condition score data supplied by the American Angus Association were used to determine the effect of body condition score on cow weight and to compute condition score adjustment factors. Single records on 11,301 cows for weight and 7,769 cows for height were collected at or near weaning, at which time a subjective condition score (9-point scale) was taken. Limited information on extreme scores 1 and 9 allowed only scores 2 through 8 to be included in the analysis. Cows were grouped into age classes corresponding to 2, 3, 4, 5, 6, 7 to 10, and 11+ yr of age. The mathematical model for a weight record included effects of fixed herd, year-month the record was collected, cow age, body condition score, and a random residual error term. The model for height excluded the condition score effect. Effects of herd, year-month, and cow age were highly significant (P less than .0001) for weight and height. Body condition score was a significant source of variation in weight (P less than .0001) and accounted for 16% of the total variation. Adjustment factors for weight (kilograms) by condition score were +116 (score 2), +91 (score 3), +69 (score 4), +39 (score 5), 0 (score 6), -40 (score 7), and -86 (score 8).