Résumé : Since the very beginnings of animal domestication, humans have constantly sought to improve the performance of their livestock by selecting and crossing individuals that display advantageous traits. Selection has been accelerated with the advent of techniques of assisted reproduction (in invitro fertilization, in vitro production of embryos, embryo transfer, freezing and sexing of sperm, among others), which have made substantial contributions to making animals of high genetic quality more accessible for reproduction.