Selection for Fertility Traits

Introduction Fertility is a very complex trait, difficult to define, to record and to evaluate all the factors that influence fertility. Fertility is strongly influenced by environmental effects and in part by genetics, the male for fertilization and the female for conception. In general, the fertility trait is hereditary but only to a small degree. There does however exist sufficient genetic variance among bulls to allow for the identification and the avoidance of those animals with low fertility. This paper outlines the complexities of reproduction, fertility traits, genetic evaluations carried out by various countries for fertility, including recent Italian research on fertility and finally, selection options for the farmer to improve herd fertility.