Rare donkey's even rarer birth

The foal is only the third rare Poitou donkey in Australia

A horse has given birth to a donkey in a scientific experiment that could point the way to saving rare breeds and endangered species.

The foal is an extremely rare and prehistoric-looking animal called a Poitou.

This is the first use of the technique to foster or multiply an endangered species

Prof Twink Allen

It was implanted in the standard bred mare's womb as an embryo and delivered three weeks ago at Monash University, Australia.

The Poitou donkey embryo, created by artificial insemination, was placed in the mare because the donkey's biological mother had leg problems and veterinarians were not sure she could sustain a pregnancy.

"We had to trick the mare into thinking it was her own pregnancy," said Angus McKinnon, an honorary research fellow at Monash University's Institute of Reproduction and Development (MIRD) and guide for the horse's pregnancy.

Genetic match

The foal, yet to be named, brings to three the number of Poitous in Australia.

Although all animals in the genus Equus (horse, zebra, donkey, etc) will interbreed, they are reluctant to accept implanted embryos from each other. Data collected by Professor Twink Allen, of the Equine Fertility Unit, UK, shows that donkey embryos implanted into horses will spontaneously abort in 70% of cases, primarily because of immunological differences.

"In any mammal - humans included - the embryo must send a signal to the mother to tell her she is pregnant - otherwise, she will cycle again," Professor Allen told BBC News Online.

"When that signal is received, it switches the mother's immune system from rejecting the foreign embryo to accepting it. There are differences between individual mares as to whether they accept that message or not."

Professor Allen, who pioneered the donkey implantation technique used at Monash, described Dr McKinnon's work as "excellent".

"This is the first use of the technique to foster or multiply an endangered species and this is a very good use."

Long ears

The MIRD's animal conservation programme and gene bank project has worked on a diverse range of species, including the bilby and greater bilby, northern and southern hairy-nosed and common wombat, five species of wallabies, the black rhinoceros, red panda and the orang-utan.

A number of scientific groups around the world are examining - with some success - whether closely related species can act as surrogates for the offspring of their endangered cousins.

The Poitou donkey is the largest and hairiest donkey in the world. But there are probably fewer than 200 of the animals in existence.

"It's amazing," said Dr McKinnon of his new charge. "The foal's ears are as long as its head."