Blastocyst–Endometriuminteractions and Their Significance in Embryonic Mortality

One of the most important economic considerations for the commercial pig breeder is the number of pigs marketed per sow per year. With adequate nutritional and environmental regimes, the realization of maximal productivity is limited by the sow's reproductive potential, which in theory can be increased by reducing the farrowing interval (for instance through early weaning) and by achieving a high litter size (by raising ovulation rate and reducing embryonic, perinatal and pre-weaning losses). For a given ovulation tate, litter size is determined by losses at fertilization, during gestation and in the perinatal period. Of these, loss during gestation is quantitatively the most relevant; the majority of this loss occurs before or during embryogenesis, and is termed embryonic mortality. It has been known for some time that embryonic mortality is relatively high in the pig (Hammond, 1914; Corner, 1923; Perry, 1954; Hanly, 1961;