Theoretical studies show that rates of genetic progress in sheep could be increased by 100% through use of multiple ovulation-embryo transfer (MOET) to Increase selection intensity amongst females and reduce female generation intervals (Smith, 1986). However, there has been a slow uptake of this technology In breed Improvement programmes due to 2 main problems: (a) surgical interference with donor and recipient animals; (b) poor repeatability of superovulatory response. The first of these problems has been adequately resolved by development of minimally Invasive techniques for the recovery and transfer of embryos by laparoscopy (McKelvey, Robinson and Aitken, 1985a). The main Impediment to rapid dissemination of MOET is now the problem of inconsistent repeatability of superovulatory responses. Pregnant mare's serum gonadotrophin (PMSG) Is the most widely used gonadotropin for superovulating sheep but significant variation in ovulation rate has been reported amongst individual animals (Smith, 1988). However as the predicted genetic gains assume that MOET can consistently produce 4 progeny per donor ewe, what Is achieved in practice falls far short of the theoretical maximum. Several researchers have suggested that higher ovulation rates and less individual variation in ovulation response occur with porcine follicle stimulating hormone (FSHp) compared with PMSG (Armstrong and Evans, 1983; Moor, Kruip and Green, 1984). Compared to the single treatment of PMSG, successive treatments of FSHp are required for 3-4 days to induce superovulation due to the short half-life of the FSH molecules in FSHp.