Associations of subjective udder edema scores and descriptive trait codes for udder types

Edema severity was scored by herd personnel in six North Carolina Holstein herds from 1 (none) to 5 (extremely severe). Cows (2612) were scored at calving and 1 and 2 wk postpartum. Total score was calculated as the sum of these three scores. Official Holstein-Friesian classification descriptive udder trait codes were available on a subset of the cows. All statistical analyses were within lactation and included adjustments for herd-year and age as well as classifier and stage of lactation where appropriate. Correlations between corresponding edema scores for first and second lactations were .18, .18, .19, and .20 for scores at calving, 1 wk, 2 wk, and for total score. Stepwise regression procedures showed that udder support codes were associated with a larger amount of variation of edema scores than for any other single mammary trait code. Fore and rear udder codes also were associated with significant variation of edema scores in some analyses. Prediction models showed edema was a significant predictor of subsequent udder support codes, although udder trait codes were not significant predictors of subsequent edema severity. It appeared that severe edema may be one of the causes of pendulous udders.