SEMEN CRYOPRESERVATION, SUPEROVULATION USING A SLOW FSH RELEASING SYSTEM AND EMBRYO TRANSFER IN SHEEP IN THAILAND

Abstract

The present thesis aims to utilize the assisted reproductive technology (ARTs) as Laparoscopic Insemination and Embryo Transfer (ET) for genetic and reproduction improvement in sheep and also to apply to commercial farm in Thailand. The seasonality and environmental may affect the semen traits in imported ram under tropical conditions. Semen qualities and scrotal circumference of an imported ram varied monthly related to season and environment especially during summer. Indeed, the ram’s reproductive performances correlated with ambient temperature, humidity and day length. These results showed that the peak reproductive performances of imported ram were from December to March. Next, the effect of various and combination of sugars in semen extender for increasing frozen-thawed sperm quality have been investigated. Our findings showed that the combined sucrose and trehalose (ST) supplementation in semen freezing extender significantly improved frozen-thawed sperm qualities (motility, viability, longevity and acrosome integrity) when compared with other sugars (P < 0.05). The fertility rate after laparoscopic artificial insemination (LAI) with frozen-thawed ram semen with the best semen extender revealed the similar pregnancy rates compared with fresh semen (82% vs. 84%, respectively). Regarding the development of simplify superovulation technique in ewes, in vivo experiment was performed to compare ovarian responses and embryo yields by superovulatory stimulation with split-single FSH administration dissolved with hyaluronan (treated group; S) compared to a conventional method (multiple injections of FSH programs; control; M). The results showed no difference of the ovarian responses and embryo yields between the two groups. However, grade 1 and 2 recovered embryos in treated group tended to be higher than in the control group. Following the embryo transfer (ET), the pregnancy rates in S group (90.5%) were significantly higher (P < 0.05) than in M group (78.9%). Finally, the overall results obtained in this thesis were carried out to verify the possibility of application of both AI and ET techniques to commercial scale in sheep farm. It is found that the techniques proposed on this context can successfully translate from laboratory scale to commercial scale.