Management of the donor cow

The main pharmacological procedure applied to a donor cow is an induction of multiple ovulation to maximise the yield of embryos for transfer. The induction of poliovulation is performed with gonadotrophins during an oestrus cycle synchronised with prostaglandins or progestagens.

FSH

Natural FSH preparations, of porcine and ovine origin, are available. Because FSH has a relatively short half-life, it is generally administered twice daily for 3-4 days.

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Example 1: Crestar and FSH

Example 2: Prostaglandins and FSH

PMSG

Pregnant mare serum gonadotrophin – PMSG (Folligon®) has a long half-life, so a single injection is sufficient. The continued stimulant effect of high doses of PMSG may have a negative effect on ovulation and cause the emergence of a second wave of follicles. 48 Hours after the PMSG (or the first FSH) injection, regression of the corpus luteum is induced with a dose of prostaglandin.

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Example 1: example 1 - superovulation program using Crestar

Example 2: example 2 - superovulation program using Crestar

Factors affecting embryo yield

  • Stage of the cycle
    Best results are obtained when superovulation is initiated during the mid-luteal phase (day 9-13).
  • Follicular status at the time of superovulation
    The presence of a large dominant follicle at the time of superovulation reduces the response
  • Management of donors
    • Avoiding stress
    • nutritional status
    • absence of pathology.
  • Semen/insemination
    • Use of high quality semen and AI at 12-24 hours after the onset of standing oestrus
    • Repeated inseminations do not appear to give better fertilization rates
    • Differences have been reported between bulls
cows