USE OF REAL-TIME ULTRASOUND TO IDENTIFY MULTIPLE FETUSES IN BEEF CATTLE

Abstract To examine the feasibility of producing multiple births in beef cattle by means of superovulation, realtime ultrasound was used to identify cows carrying multiple fetuses. Three replicates of the superovulation experiment were conducted with groups of 52, 25 and 89 purebred Angus cows, respectively. Both uterine horns of cows from Replicate 1 were examined via the rectum using ultrasound at averages of 43 (range = 30 to 68 days), 51 (range = 38 to 76 days) and 126 (range = 113 to 151 days) days after AI. Cows in Replicate 2 were examined in the same fashion at averages of 55 and 97 days post insemination. In Replicate 3 the number of fetuses was estimated on a single date (average number of days post insemination = 49 days). Across the 3 replicates, the number of fetuses was most accurately assessed at an average of between 49 and 55 days post insemination. In most instances for which comparability between ultrasound estimations and calving results was low, the lack of correspondence was likely due to embryo mortality in cows identified as carrying multiple fetuses. For all 3 replicates combined, only 1 cow diagnosed with a single fetus produced multiple calves at birth when the diagnoses were conducted at 49 to 55 days post insemination. Real-time ultrasound can be used to accurately identify open cows and to differentiate between cows carrying single or multiple fetuses.