Oestrus synchronisation and superovulation using equine FSH in crossbred ewes
Sharma, V.K.; Gupta, R.C.; Khurana, N.K.; Khar, S.K.
Veterinary Record 135(7): 164-165
1994
ISSN/ISBN: 0042-4900 PMID: 7985348 Document Number: 423865
Corriedale cross Nali ewes (14 in breeding season, 9 not in breeding season) aged 2 to 5 years were synchronized and superovulated using equine follicle stimulating hormone (FSH-E) in combination with norgestomet-oestradiol preparation (Crestar). Ewes were hand mated 2 to 3 times with fertile rams at 12 h intervals after oestrus had been detected. Gonadotrophin releasing hormone (GnRH) was administered at the first mating to synchronize ovulations. Similar proportions of ewes responded to induction of oestrus synchronization during (11 of 14) and out of the breeding season (7 of 9). Most ewes (9 and 5, respectively) showed oestrus within 24 h of implant withdrawal. The average duration of oestrus was 26.18 +or- 1.46 h during the breeding season and 30.86 +or- 2.42 h in the non breeding season. The ovarian responses, recorded at laparotomy 6 days after oestrus and embryo recovery rates were similar in both groups: 11.82 +or- 1.22 corpora lutea, 0.27 +or- 0.14 unovulated follicles and 4.91+or- 0.79 embryos in the breeding group and 9.57 +or- 1.13, 1.29 +or- 0.47 and 3.57 +or- 0.48 in the non-breeding group, respectively. All 79 recovered embryos were fertilised although 6.33% were retarded and 23% showed evidence of degeneration; 62 were morulae and 12 were blastocytes. The FSH-E/GnRH combination used in this study was shown to be effective for oestrus synchronization and superovulation in sheep; however the embryo recovery rate was rather low.