Abstract
Estrus was induced by three treatments and their utility for embryo transfer was investigated. The treatments were as follows: Treatment I, PMSG-hCG treatment on the day of weaning (23 sows); Treatment II, PMSG-hCG treatment after injection of PGF2α analogue (26 pregnant gilts); Treatment III, PMSG-hCG treatment after Altrenogest administration (23 cyclic gilts). Estrus was detected by checking twice with mature boars. A high proportion of animals showed estrus on day 0 (day 0: the day of hCG injection) to day 1 for the Treatment I and II, and on day 1 for: III. The incidence of cystic ovaries was observed in three pigs after the Treatment I. The pigs exhibited estrus were inseminated 2-3 times, and then the recovery of embryos was carried out on day 5-8. The proportion of normal embryos in the Treatment I, II and III were 81.8%, 81.0% and 52.5% respectively (Treatment I & II vs III: p<0.05). Thirteen to 22 normal embryos were transferred to recipients synchronized by the three treatments. The conception rate was lower in the Treatment III than the Treatment I, but the difference was not statistically significant. In conclusion, the Treatment II is suitable for estrus synchronization in gilts, whereas the utility of the Treatment III appears to be so far questionable. Although the incidence of cystic ovary was observed, the Treatment I is available for sows.
