Cow and management factors and their association with estimates of uterine size and position at the time of insemination of dairy cattle.

This study examines factors affecting uterine size and position determined at 30-36 days postpartum in dairy cattle. The final study population consisted of 328 dairy cows, all calving during the warm season. Uterus position (pelvic, pelvic-abdominal, abdominal) and uterus size (small, medium, large) was measured by ultrasound on Day 30-36 postpartum. Multiparous cows had a larger uterus positioned in the abdominal cavity (p = .03) and a male newborn was associated with a larger uterus (p = .022). The number of cows with the uterus in the abdominal cavity was higher among multiparous and high producer (p < .0001) cows. High producers were 0.41 times more likely to have a small uterus in a pelvic position. The most important finding of this study was that the delivery of a male dairy, rather than beef, calf was related to the least optimal maternal uterus size and position.