Essais de production et de collecte d’embryons chez la vache Somba

Trials were conducted to collect embryos in a herd of trypanotolerant Somba cows. The trial period covered four superovulation cycles induced during various seasons. A progestagen (Norgestomet, Crestar® Intervet) and gonadotropins (p-FSH Pluset® Serono, or Folltropin® Vetrepharm) were used at various doses according to the animal weight. The donors were then fertilized twice at 12-hour interval, either by natural or artificial insemination, the semen of three bulls having been previously collected and frozen in straw on the site. The overall superovulation response rate was 72%. The embryos were collected at 6.5 days at the stage of compacted morula or young blastocyst. Of the 30 flushings performed, 87 embryos were recovered. Among them, 39 (45%) belonged to categories Q1 and Q2, and could be cryopreserved, 19 (22%) belonged to category Q3, and the remaining 29 (33%) belonged to category Q4 (non-viable). The average production of viable embryos (1.9 per donor) was not significantly affected by the type of gonadotropin used. However, the rate of embryos that could be selected for cryopreservation was higher in the cool rainy season than in the hot rainy season (59 vs 38%, respectively).