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Embryo transfer (ET) allows competition mares to keep performing while passing on their genes to the next generation.

One of the major advantages is being able to breed more than once from a mare in one breeding season. It is quite usual for two different stallions to be selected and the ET process carried out twice, enabling one mare to produce two foals by two different stallions.

ET involves the transfer of an embryo from a mare who has been covered to a recipient. It is important that the recipient mare is at a similar stage in her cycle (ideally one to two days behind the donor mare) to ensure that the embryo is being placed into a receptive environment.

Research has shown that the optimum time to perform the transfer is when the embryo
is eight days old.

It is removed from the donor mare by flushing a sterile solution into the uterus; this fluid is then siphoned back out of the uterus and passed through a fine filter, which catches the embryo.

The embryo is then inserted through the cervix into the uterus of the recipient mare.
The international average for embryo recovery is 50%. There is an overall success rate of 40% per embryo flush.

For the full embryo transfer diary, see the current issue of Horse & Hound (2 June, 2011)

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