Determination of the Genital Tubercle Migration Period in Morada Nova Sheep Foetuses by Ultrasonography

Abstract

The aim of this study was to determine the period of genital tubercle (GT) migration using ultrasonography in Morada Nova sheep foetuses (n = 117) from natural mating (NM) and frozen embryo transfer (ET) to determine the window when foetal sexing can be determined. The examinations were performed using transrectal ultrasonography with a dual-frequency linear transducer (6.0 and 8.0 MHz) from day 30-54 of pregnancy at 48-h intervals. The period of GT migration of foetuses produced by NM varied from 36 to 46 days of pregnancy, resulting in an average of 39.5 +/- 2.9 days. For foetuses derived from ET, GT migration varied from 42 to 52 days of pregnancy with an average of 48.5 +/- 3.3 days, being possible the GT of foetuses from ET start to migrate 96 h later even if they are of the same gender. Migration of the GT occurred earlier (p < 0.05) in foetuses produced by NM and sexing accuracy for triplet pregnancies (77.8%) was significantly inferior (p < 0.05) to single (100%) and twin (92.9%) pregnancies for foetuses derived by NM. The results allow one to conclude that foetal sexing can be done from the 50th day onwards in foetuses produced by NM and from the 55th day onwards in foetuses derived from ET, and that multiple pregnancies compromise the sexing accuracy by ultrasonography.

Migration time of the genital tubercle in caprine and ovine fetuses: Comparison between breeds, sexes and species

“…The breed effect on fetal sexing precocities, based on the final GT position verified in goats, was determined by Saanen fetuses, especially in those diagnosed as female. The same result was reported by Santos et al (2007f), evidencing that the GT of American Alpine fetuses had their migration anticipated to the Saanen breed. In bovines, Curran et al (1989) observed that the GT of female fetus migrates before the male, because the migration distance covered by the structure is shorter in female; however, in this work it was evident that GT mi- It is interesting to emphasise that due to tail proximity; the operator has more difficulty in diagnosing the sex of female fetuses, owing to the difficulty in determining the final position of the GT by visualisation of a hyperechoic point on the monitor screen.…”

“…Previous works conducted with sheep of the breeds Santa Inês (Santos et al, 2006a), Dorper (Santos et al, 2007a), Damara (Santos et al, 2007e) and Morada Nova (Santos et al, 2007f) and with goats of Anglo-Nubian (Santos et al, 2005a), Boer (Santos et al, 2006b), Saanen (Santos et al, 2007c) and American Alpine (Santos et al, 2007f) breeds provided data that endorse the considerations here mentioned. The authors above-mentioned suggestion about sexing ovine fetuses from day 50 of pregnancy and goat fetuses from day 55 of pregnancy must be considered because it limits or even eliminates the inaccurate diagnosis, especially in male fetuses sexed as female.…”

“…The authors above-mentioned suggestion about sexing ovine fetuses from day 50 of pregnancy and goat fetuses from day 55 of pregnancy must be considered because it limits or even eliminates the inaccurate diagnosis, especially in male fetuses sexed as female. Although this kind of mistake has not been committed in this work, it is necessary to account for the exceptions, in which GT migration in fetuses occurs in a delayed form, which may be observed in twin pregnancies with fetuses of the same sex, as reported by Santos et al (2007f). The breed effect on fetal sexing precocities, based on the final GT position verified in goats, was determined by Saanen fetuses, especially in those diagnosed as female.…”

Pregnancy diagnosis, fetal quantification and gender estimation by ultra-sonography in ewes

“…This occurred because the pregnancy diagnose in ewes at 35 days of gestation is facilitated by the large amount of fluid within the uterus, which forms a well characterized non-echogenic image, besides the visualization of the fetus itself and of the heart beats (Santos, 2004).…”

“…P. 3037 -37200-000 -Lavras, Animal Scientist, master student -Departamento de Zootecnia/DZO -Universidade Federal de Lavras/UFLA -Cx. P. 3037 -37200-000 -Lavras, MGmila_zoo@yahoo.com.br and survival (White et al, 1984;Gearhart et al, 1988;Santos et al, 2004 and2007b).…”