Superovulation in mares

Abstract

Superovulation could potentially increase embryo recovery for immediate transfer or cryopreservation. The objectives of this study were: a) to evaluate the effect of different frequencies of FSH administration and b) to compare the superovulatory response between porcine FSH and recombinant equine FSH. In experiment 1, 38 mares were assigned to one of 5 treatment groups. Group 1 consisted of untreated controls. The treatment groups were administered porcine FSH in different doses and frequencies. Treatment started when follicles reached 18-22 mm in size and on the second day of treatment a dose of prostaglandins was administered. The FSH treatment continued until follicles reached 35 mm in diameter. None of the mares responded to the porcine FSH treatment; no multiple ovulations were observed. In experiment 2, recombinant equine FSH was used to induce superovulation. Mares were randomly assigned to one of three treatment groups. The same control group as in experiment 1 was used. Mares were administered 0.25 mg four times a day, 0.5 mg four times a day or 0.5 mg twice a day. The rest of the treatment protocol was identical to experiment 1. The number of pre-ovulatory follicles and ovulations was significantly higher using reFSH compared with the pFSH. A higher frequency of reFSH administration resulted in a better superovulatory response. On an average the 0,5 mg reFSH QID treated mares experienced 4.0 ovulations versus 0,8 ovulations in the 0,5 mg reFSH BID treatment group. The embryo recovery per ovulation ratio was low in the reFSH treated mares, depending on the treatment group varying between 0.2-0.6. The individual variation in response to the reFSH treatment was enormous and several negative side effects were observed. Recombinant equine FSH can be used with success to induce superovulation in mares.