Abstract
It is recognised that infecundity and infertility are among the major problems which confront the breeder of livestock, and in this country, as elsewhere, investigation into their causes, prevention, and cure is actively encouraged. A number of pathological and nutritional factors have been shown to lie at the root of these conditions, and it has become abundantly clear that in many instances genetic factors are undoubtedly responsible for the inability on the part of the individual to elaborate functional gametes and/or of these gametes in their union to give rise to fully viable zygotes. These factors may be discovered in intergeneric crosses.