DETERMINATION OF THE GENITAL TUBERCLE MIGRATION PERIOD TO EARLY SEXING SHEEP FETUSES OF DAMARA, SAINT INES AND 3/4 CROSSBRED DAMARA-SAINT INES

Abstract

The objective was to determine the genital tubercle (GT) migration period to establish the ideal timing for sexing fetus from Damara, Santa Inês and 3/4 crossbred Damara-Santa Inês (¾ D-SI) breeds by ultrasound. The transrectal ultrasound was performed with a double frequency linear transducer (6.0 and 8.0 MHz) every 24 hours from day 30 to day 60 of pregnancy. The GT migration period ranged from 38 to 51 days in Damara fetus, 37 to 46 days in Santa Inês fetus and from 36 to 45 days in ¾ SI-D fetus. The mean GT migration period was 45.0 ± 3.0, 42.0 ± 2.0 and 39.2 ± 2.3 days for Damara, Santa Inês and ¾ D-SI fetus, respectively. There was a breed difference on GT migration period. It was earlier (P < 0.05) for ¾ D-SI fetus than Damara and Santa Inês fetus and it was later (P < 0.05) for fetus from the breed Damara as compared to Santa Inês fetus. The accuracy of fetus sexing in single pregnancies (100%) was higher than (P < 0.05) double pregnancies (88.5%). In conclusion, the GT migration period differs among Damara, Santa Inês and ¾ D-SI breeds. Moreover, the ideal time for sexing fetus from these breeds is from day 50 of pregnancy and the accuracy of the ultrasound examination is compromised by double pregnancies. KEY WORDS: Genital swelling, nipples, prepuce, scrotal bag, ultra-sonography.