Genetics of reproduction in ruminants

Abstract

Reproduction is of prime importance for the profitability of a herd, it is a prerequisite of every animal production. The breeding ability during the productive life of an animal depends on sexual maturity, fertility and prolificacy the components of which are the ovulation and the embryonic mortality rates. Those traits are studied in animal breeding and are variously taken into account in the purebred and crossbred selection schemes. Sexual maturity and prolificacy have to be improved when they are limiting factors, but for economic reasons they have to stay beneath optimal thresholds. Studying the components of prolificacy would allow a better control. Maximal fertility is always expected, but its improvement is made difficult because it depends on numerous factors : sex (female fertility is often the more limiting), reproduction technique used (natural or artificial) and the choice of the breeding period (time between littering and breeding, season). Research on genetics of the breeding traits has to be pursued, while including the recent advances in genetic cartography.