ULTRASONIC DETERMINATION OF FETAL GENDER IN HORSES AND CATTLE UNDER FARM CONDITIONS

Accuracy of transrectal ultrasonic diagnosis of fetal gender by identifying and locating the genital tubercle was assessed in 85 horses and 102 dairy heifers and cows. Examinations were made once (horses and cattle) under farm conditions (cattle) on approximately Days 50 to 100. Definite diagnosis was made by removal of fetuses (horses) or after calving or abortion (cattle). In both species and both parities, accuracy was 100% (109/109 totaled over both species) when the certainty level recorded at the time of examination was 95 or 99%. At the lower levels of certainty (65 to 80%, 85 to 90%), the accuracy was 89% (57/64 totaled over both species). A diagnosis was not obtainable in 10 horses (12%) and 5 cattle (5%); this was especially due to inadequate viewing of the fetus when the fetus was beyond Day 64. The time from completion of evacuation of the rectum to diagnosis of gender averaged 1 minute 17 seconds in horses (range, 15 seconds to 3 minutes 55 seconds). The corresponding figure in cattle was 1 minute 53 seconds (range, 16 seconds to 8 minutes 30 seconds).