Estrus Detection Intensity and Accuracy, and Optimal Timing of Insemination with Automated Activity Monitors for Dairy Cows
This thesis was conducted to evaluate automated activity monitors (AAM) for estrus detection and to identify the time interval after activity alert that optimizes pregnancy risk. A study was conducted on four dairy farms using one of two AAM systems for inseminations before 80 days in milk (DIM). Activity monitors identified 83% of cows in estrous by 80 DIM. Anovular or multiparous cows, cows with purulent vaginal discharge, or lame cows with body condition score ≤ 2.5 had higher odds of not being detected in estrus by 80 DIM. In a sample of inseminations based on AAM, only 3% were not in estrus based on serum progesterone concentration. The probability of pregnancy was higher for primiparous cows inseminated 0 to 8 hours after AAM alert but was not different for multiparous cows inseminated 0 to 8 h, 8 to 16 h or 16 to 24 h after AAM alert.