Multiple ovulation & embryo recovery

Multiple ovulation & embryo recovery

The synchronisation and induction of multiple ovulation (sometimes called ‘superovulation’) in donor hinds uses intravaginal progesterone CIDR devices (see Artificial Insemination) to synchronise the onset of oestrus and ovulation (as for AI) and various gonadotrophic/pituitary hormones to cause multiple eggs ('ova') to be shed by the ovaries at the end of the synchronisation procedure.

What materials are involved?
The main hormones used are Follicle Stimulating Hormone (FSH) and equine Chorionic Gonadotrophin (eCG). The actual combinations of hormones, the dosages and the delivery schedule are determined by the AB professionals based on a number of factors, including hind genotype and body mass. eCG is not always used in MOET programmes, and if it is , seldom without FSH. Because FSH has a short half-life following injection, it is normally administered a 12-hour injections for 3-4 days around the timing of CIDR device removal.

What is the procedure?
The general procedure for synchronising and multiple ovulating donor hinds is as follows:

  1. Two CIDR devices are tied together and inserted into the anterior chamber of the vagina (as for AI).
  2. CIDR devices are removed 12 days later. Starting 12-24 hours before CIDR device removal, donor hinds each receive intramuscular injections of FSH for up to 4 days.
  3. Donor hinds are joined with stags shortly after CIDR device removal or are artificially inseminated (see Artificial Insemination) 36-44 hours after CIDR device removal (note that this is earlier than for AI).

The next step is to recover embryos 5-6 days following mating/insemination. This is usually done by surgical laparotomy, whereby the uterus is exteriorised and cathetarised to allow flushing of embryos from the tract. Obviously this is a highly technical operation by highly skilled professionals, involving full anaesthesia of the hinds.

Embryos are flushed into a glass dish and visualised under the microscope to assess their developmental stage and viability. The desired embryo stages for cryopreservation or direct transfer are morulae and blastocysts.

Meantime, the donor hinds are stitched up and undergo recovery from surgery. They are normally re-united with stags a week or two later in order to get pregnant.