PSXI-22 Efficacy of estrus detection by an ear-tag activity monitoring system for beef females.

Abstract We investigated the efficacy of an ear-tag activity monitoring system (xTpro, 701x, Fargo, ND) equipped with a 3-axis accelerometer and gyroscope to accurately identify beef cows in estrus. A total of 20 Angus-crossed beef heifers were enrolled in the study. Heifers were maintained in a single pasture of approximately one acre for the duration of the 31-day experiment. The pasture was equipped with 8 monitoring cameras with night vision capability, which allowed for complete visibility of the pasture and videos were recorded 24 hrs a day. At the initiation of the study, heifers received the xTpro tag and a large flag number was glued to each side of the body for improved ease of identification and were enrolled in the 7-day CO-Synch+CIDR estrous synchronization protocol. In brief, heifers received an 100-μg injection of GnRH (2 mL Factrel; Zoetis Animal Health) at CIDR (1.38 g P4; Zoetis Animal Health) insertion [d -10] with 25-mg injection of prostaglandin F2α (5 mL Lutalyse; Zoetis Animal Health) at CIDR removal and placement of an estrus alert and breeding indicator (Estrotect; MAI Animal Health) [d -3], followed by injection of 100-μg GnRH and fixed-time artificial insemination [d 0] by 66 h after CIDR removal. Estrus detection was performed visually three times daily from 7:00 to 8:00, 14:00 to 15:00 and 18:00 to 19:00, between days -3 and 0, and days 16 to 21, where new estrus detection alert patches were placed. Heifers visually observed to stand to be mounted and/or with an activated estrus alert were recorded with date and time of observation. Video images were then used to determine the exact date and time of start and end of estrus behavior. A total of 16 heifers presented estrus behavior confirmed by the videos and visual observations, the ear-tag monitoring system correctly identified 16 heifers in estrus (true positives), 0 heifers not in estrus (true negatives), 10 heifers in estrus incorrectly (false positives), and 1 heifers not in estrus incorrectly (false negatives). The sensitivity of the ear-tag monitoring system was 94.1%, specificity was 0.0% and accuracy was 59.3%. The ear-tag activity monitoring system (xTpro) showed no specificity and low accuracy, and high sensitivity for detecting estrus in beef heifers, indicating its potential as a valuable tool for estrus detection of beef females upon further calibration an refinement of the system.