Mounting activity detected by me ans of mounting activity monitors of beef females administered norgestomet and estradiol valerate for estrus synchronization

One hundred and ninety-one beef females were administered Syncro-Mate B for estrus synchronization. At the time of implant removal, females were administered either a KaMar heatmount device or Heat-mark marking paint. Immediately before AI, 48 hours after implant removal, the status of the devices and paint were evaluated. The status of the KaMar heatmount device was recorded as white, partial (both red and white), red and missing. The status of the Heat-mark marking paint was recorded as <10% paint removed, 10-89% paint removed and ≥ 90% paint removed. Overall', 43-44% of the females calved from the synchronized AI. Fifty-four percent (52/97) and 30% (24/79) of the females classified in estrus (red KaMar heatmount device or ≥ 90% Heat-mark marking paint removed) or not in estrus (partially red or white devices or < 90% paint removed), respectively calved Females classifed in estrus had a higher (P<0.01) calving rate than females classified not in estrus; however; a valuable number of females not in estrus calved. Results from this study support the recommendation that females synchronized with Syncro-Mate B be bred at a predetermined time, about 48 hours, after norgestomet implant removal. Both methods of identifying females in estrus were similar (P>0.10), but because 12.5% of the females (n=15) lost their KaMar heatmount devices, the Heat-mark marking paint may be more useful if estrus detection is needed to select females with optimal fertility.