Transfer of exotic equine embryos to domestic horses and donkeys

Abstract

Summary A total of 43 non‐surgical embryo recoveries performed on two Przewalski's horse mares (Equus przewalski) and two Grant's zebra mares (E burchelli) yielded 11 Przewalski and 14 zebra embryos. Surgical transfer of nine Przewalski embryos to domestic pony recipient mares resulted in seven (78 per cent) extraspecific pregnancies. Two of these recipient mares gave birth to live foals on Days 324 and 329 of gestation respectively and two are at Days 175 and 166 respectively at the time of writing; three conceptuses were resorbed at various times between Days 20 and 100. Non‐surgical transfer of two Przewalski's horse embryos and flank surgical transfer of one other Przewalski's horse embryo to domestic mares failed to establish any pregnancy. Surgical transfer of five zebra embryos to domestic pony recipients resulted in three (60 per cent) extraspecific pregnancies; one conceptus was resorbed between Days 61 and 70 and the other two are at Days 190 and 201 respectively at the time of writing. Surgical transfer of seven zebra embryos to jenny donkeys gave two (29 per cent) extraspecific pregnancies; one conceptus was resorbed between Days 53 and 79 and the other foal was born prematurely on Day 292 and lived for only 3 h. Non‐surgical transfer of one Day 10 zebra embryo to a jenny donkey did not result in a pregnancy. These experiments demonstrated that it is possible repeatedly to recover embryos non‐surgically from sedated wild equids and transfer them successfully to domestic horse and donkey recipients. The production of such extraspecific pregnancies by embryo transfer has considerable value as a research tool and the technique should also prove valuable in the future for maximising the reproductive potential of endangered equine species in captivity.