PSXIV-5 - Classification of postpartum beef cows as estrous cycling or anestrous through the use of estrus detection patches

Abstract: Application of estrus detection patches for an extended period of time was evaluated as a means of classifying postpartum beef cows as estrous cycling or anestrous at the start of the breeding season. Estrus detection patches (Estrotect Breeding Indicators; Hermitage, TN) were applied to 269 primiparous and multiparous postpartum beef cows in three locations 24 days prior to the start of an estrus synchronization protocol. At the start of the protocol, patches were scored using a 1 to 4 scale (1 = 0-25%; 2 = 25-50%; 3 = 50-75%; 4 = 75-100%), with scores of 3 or 4 considered activated. Estrous cyclicity status was determined via transrectal ovarian ultrasonography performed by experienced technicians coincident with the start of an estrus synchronization protocol. Cows were classified as cycling based on the presence of a corpus luteum (CL). Based on transrectal ovarian ultrasonography, 59% (161/269) of cows were cycling at the start of estrus synchronization. Of cows receiving patches, 95% (256/269) of cows retained patches for the full 24 day period. Among cows retaining patches, 67% (171/256) of cows presented with activated patches, and 33% (85/256) of cows presented with non-activated patches at the start of the synchronization protocol. Among these, 139 cows presented with activated patches and were observed to have CL via ultrasound, therefore being considered true positives (i.e., estrous cycling). A total of 69 cows presented with non-activated patches and were observed to have no CL via ultrasound, therefore being considered true negatives (i.e., anestrous). Among cows for which patch score did not result in the same classification as an ultrasound-based characterization of CL status, 32 were considered false positives (i.e., activated patch but no CL observed via ultrasound), and 16 were considered false negatives (i.e., non-activated patch but CL observed via ultrasound). Based on these observations, use of activated patches to infer cyclicity resulted in 89% sensitivity, 68% specificity, and a positive predictive value of 78%. When retained, estrus detection patches are a sensitive tool to classify postpartum cows as cycling prior to the start of an estrus synchronization protocol.