Relationship between body condition scores and conception at first artificial insemination in a large dairy herd of high yielding Holstein cows.

This study investigated the relationship between changes in body condition during the dry period and early lactation and conception to first postpartum AI. Holstein cows (n = 720) on a commercial dairy farm were scored weekly for body condition beginning at dry-off and continuing until first AI. Occurrence of postpartum diseases was recorded. A multiple logistic regression model was a significant predictor of the success or failure of conception for multiparous cows, but not for primiparous cows. Principal component analysis reduced collinearity among independent variables and allowed the variables to be ranked based on their contribution to the interval from first AI to conception. The top three ranking variables were lactation number, milk yield at 120 d of lactation, and change in body condition score between parturition and wk 4 of lactation. Increased milk yield at 120 d of lactation was associated with an increased likelihood of conception, and decreased body condition during the 1st mo of lactation was associated with a decreased likelihood of conception. Health problems were less associated with conception than were body condition or milk yield in this herd. Body condition during the dry period and during the first 30 d of lactation is an important tool to identify cows at risk for failure to conceive at first AI.