RESUMO
The objective of this study was to determine the accuracy of early fetal sex determination by ultrasonic assessment of the relative location of the genital tubercle (GT) in goats at different stages of pregnancy as well as by the identification of fetal external genitalia. Pregnant animals were divided into three experimental groups (EI: n=21, EII: n=28, EIII: n=33). In EI, fetuses (n=27) were transrectally monitored daily from days 40 to 60 of pregnancy with a linear transducer (6.0 and 8.0MHz). In EII, fetuses (n=40) were examined once between days 45 and 70 of pregnancy by transrectal ultrasonography. In EIII fetuses (n=52) between days 100 and 120 of pregnancy, were submitted to a single transabdominal ultrasonography using a convex transducer (5.0 and 7.5MHz). Regardless of fetal sex diagnosis, 15/15 (EI), 13/16 (EII) and 9/14 (EIII) of single pregnancies and 10/12 (EI), 20/24 (EII) and 21/38 (EIII) of twin pregnancies were correctly identified. The accuracy of sex identification among EI (92.6%), EII (82.5%) and EIII (57.7%) was not statistically different (P>0.05). Identification of the GT in male fetuses was possible from day 45 onward. Changes in the GT position were not observed between days 53 and 60 of pregnancy. Accuracy of fetal sexing under field conditions is high in goats when ultrasound imaging is properly timed during pregnancy and when it is performed with proper equipment by experienced operators.