Interrelationships With Estrous Behavior and Conception in Dairy Cattle

Abstract

A total of 199 inseminations and estrous periods of lactating cows and heifers of breeding age were used to assess behavioral, productive, environmental, and hormonal events at first observation of estrus and those 12h later with concurrent breeding efficiencies. Cattle were observed twice daily for estrus, and blood samples were collected at the initial observation of estrus (0h) and at 12h. Fifty-one percent of the cattle first were detected in estrus in the morning. Morning estrous activity was greater (11.4 mounts/h) than that first observed in the evening (7.6). Mean estrous activity declined from 9.4 mounts/h at 0h to 1.6 mounts/h at 12h. Older cows exhibited more mounting activity than younger animals at 0h. Barn housed cattle exhibited more mounts/h during detection of estrus (11.2) than cattle housed primarily in free stalls (6.5) or pasture (5.4). Early estrous activity (0h) was not affected by estradiol, progesterone, or luteinizing hormone. However, estradiol and progesterone did exert an influence on activity seen at late estrus (12h). Glucose and urea at 0 and 12h were similar. There were no significant correlations of glucose or urea of plasma with estrous activity or conception. Feed intake and milk production from 3 days prior to 3 days postestrus did not change. Season affected estrous activity and conception. Highest conception was associated with low progesterone at 12h.