Utilização do ultrassom para diagnosticar a prenhez e o sexo de fetos de pequenos ruminantes gerados a partir de monta natural e da transferência de embriões frescos, congelados e vitrificados

Abstract

In this work, divided into three experiments, the aim was to verify the possibility to diagnose the pregnancy of does and ewes by different pathway access and diagnose the fetuses sex originated by natural mating and transfer of fresh and cryopreserved embryos. The examinations were carried out using an ultrasound scanner equipped with a linear transducer (6.0 and 8.0 MHz) used by transrectal and transabdominal via and a microconvex endocavitary (5.0 and 7.5 MHz) transducer used by transvaginal via. In the first experiment was verified the viability of the ultrasound examination by transretal, transabdominal and transvaginal via to diagnose pregnancy in goats (n = 240) and ewes (n = 320) at days 30th, 45th, 60th and 75th. In does and ewes the ultrasound examination was faster (P < 0.05) on days 30th and 45th of pregnancy, however by transabdominal via was faster on day 60th and 75th. In both species the time of pregnancy diagnose was greater (P < 0.05) on day 30th than the others days while this time was smallest (P < 0.05) at day 75th than day 45th and 60th. Independent of the examination via and the day of pregnancy the average time to diagnose the pregnancy was shorter (P < 0.05) in does than in ewes. Independing of the specie and the day of pregnancy the average time to diagnose the pregnancy by transrectal via was shorter (P < 0.05) than the other vias and the transvaginal via was shorter (P < 0.05) than the transabdominal one. In the second experiment, in order to improve the sexing of Boer fetuses (n = 123) by transrectal ultrasonography, the aim was to identify the migration period of the genital tubercle and its later differentiation into genital structures in fetuses derived from natural mating (TI) and fetus from fresh (TII), frozen (TIII) and vitrified (TIV) embryo transfer collected 7 days after breeding. Migration of the genital tubercle occurred earlier (P < 0.05) in TI (45.21 ± 3.31 days) than in TII (48.50 ± 3.70 days), TIII (48.93 ± 3.61 days) and TIV (48.85 ± 3.23 days). The visualization of the scrotum, prepuce and vulva occurred earlier (P < 0.05) in TI (51.20 ± 2.56; 50.35 ± 1.59; 49.75 ± 1.73 days) than in TII (53.25 ± 2.02; 53.37 ± 1.92; 51.76 ± 2.10 days),TIII (53.37 ± 1.92; 52.31 ± 2.00; 51 ± 78 ± 2.22 days) and TIV (54.06±1.75; 52.46 ± 1.95; 51.91 ± 2.06 days). In the third experiment, in order to improve fetal sexing by ultrasonography in Dorper ewe breed (n = 130), the objective was to identifythe migration period of the genital tubercle and the period of the visualization of external genital structures in fetuses derived from natural mating (TI) and from fresh (TII), frozen (TIII) and vitrified (TIV) embryos transfer collected 7 days after breeding. Migration of the genital tubercle occurred earlier (P < 0.05) in TI (42.21±2.86 days) than in TII (43.98±3.00 days), TIII (44.97±1.83 days) and TIV (44.58±1.97days). The visualization of scrotal bag, prepuce and vulva occurred, respectively, earlier (P < 0.05) in TI (45.22±1.25; 45.95±1.53; 45.01±.103 days) than in TII (48.91±1.92; 48.52±1.41; 47.41±1.41 days), TIII (49.97±1.08; 49.18±2.00; 47.64±1.82 days) and TIV(50.12±1.66; 49.27±1.1.61; 47.93±1.92 days). The results allow to conclude that the pregnancy diagnose may be performed by transrectal, transabdominal and transvaginal via, as well as, that is faster by transrectal via and hat the time for diagnosing is shorterin advanced pregnancy and in goat specie. Is also possible to conclude, taking into consideration the final position of the genital tubercle, that goat fetal sexing can be done from the 55th day onward in fetuses produced by natural mating and from the 60th day onward in fetuses derived from cryopreserved embryos. It can also be concluded that, real-time ultrasonography is a reliable tool for fetal sex determination in sheep after Day 50 of pregnancy taking into account both the location of the genital tubercle and the identification of external genital structures. In ovine species the fetal sexing can be done from the 50th day onward in fetuses produced by natural mating and from the 55th day onward in fetuses derived from cryopreserved embryos. Finally is possible to conclude that real-time ultrasonography is a reliable tool for early pregnancy diagnose in small ruminant as well as that to identify the sex on the first 60 days of pregnancy.