Multiple superovulations in N'Dama heifers.

Five N'Dama heifers were superovulated with follicle stimulating hormone (FSH-P or Folltropin) a total of six times each. The superovulations were carried out between ongoing experimental Trypanosoma congolense infections. Twenty-four (80%) of the 30 superovulations had a good ovarian response with 21 (70%) producing an average of 2.7 +/- 0.4 (mean +/- s.e.m.) embryos. The highest embryo production was achieved at the third and fourth superovulation, after which both the number of embryos and their quality declined. The overall pregnancy rate after transfer into Boran (Bos indicus) cow recipients was 50.9%. The uteri of the heifers increased considerably in size throughout the six superovulations which made it difficult to flush some of the animals after the third superovulation. Embryo transfer technology is a useful breeding tool in N'Dama heifers and multiple superovulations can be carried out with success.

Superovulation, collection and transfer of embryos and demi-embryos from Boran(Bos indicus ) cows and heifers.

Twenty-three Boran(Bos indicus ) cows and heifers were superovulated with pregnant mare serum gonadotropin (PMSG); a total of four embryos and 4.1 +/- 0.3 (mean +/- SEM) ova per ova-producing donor resulted. Follicle stimulating hormone (FSH-P) was then used to superovulate 49 Boran cows for a total of 106 superovulations, of which 63 (59.4%) produced an average of 3.7 +/- 0.4 (mean +/- SEM) embryos. The embryo production was not influenced by either the season or the number of times(one to five) the cows were superovulated. A higher pregnancy rate was obtained when the selection of Boran recipients was based on their plasma-progesterone values (overall 52.5%, single embryos 63.3%, twin demi-embryos 45.8%) than when they were selected by palpation per rectum only (overall 43.8%, single embryos 50%, twin demi-embryos 36.4%). The twinning rate of twin demiembryos was 62.5%, whereas only single calves were born after transfer of two embryos per recipient. No pregnancies were produced following transfer of twin demi-embryos without zonae pellucidae. Transferring single demi-embryos gave a low pregnancy rate (13.3%). Twelve donor Boran cows (21 superovulations) bred with their fathers resulted in a high rate of early embryonic death; additionally, only 20.9% (overall) of the recipients became pregnant. Estrus synchronization of Boran cows with a progesterone releasing intravaginal device (PRID) for a short period (7 d) combined with one injection of prostaglandin (Day 6) produced a larger number of good quality recipients (70.5%) than using double prostaglandin injections (60%).

Successful transfer of frozen N'Dama embryos from the Gambia to Kenya.

Frozen embryos from N'Dama cattle were successfully transferred from The Gambia to Kenya. Of the 26 N'Dama cows used 12 were successfully programmed to superovulate and of these seven produced 30 embryos that were collected seven days after oestrus/service. Five N'Dama bulls were used for natural service. In Kenya 29 embryos were implanted into 29 Boran heifers seven days (+/- 1) after the induction of synchronised oestrus. Eleven pregnancies were established and after one abortion of unknown aetiology at seven and a half months five female and five male calves were born and subsequently reared. During programming the N'Dama cows showed prolonged anoestrus leading to the necessity of oestrus induction using intravaginal progesterone releasing coils; pregnant mare serum gonadotrophin gave better superovulation than follicle stimulating hormone. One N'Dama bull proved to be subfertile. The success of the project has demonstrated the potential of this technique to make disease-free N'Dama available for research purposes and for the promotion of livestock development programmes in tsetse-infested areas using trypanotolerant cattle.