Female fertility in French dairy breeds: current situation and strategies for improvement.

In most countries where genetic selection for milk production has been conducted, a continuous degradation of reproductive performances has been observed in dairy cattle. This paper describes the phenotypic evolution of fertility traits in France for the main 3 dairy breeds and the different actions undertaken to counteract this unfavourable evolution of reproductive performance. In 2001, functional traits (including conception rate as a fertility trait) have been included into the French total merit index ISU, to take these traits into account in the selection objective. In addition, a marker-assisted selection (MAS) program has been developed since 2001. Through this approach, a set of QTL related to fertility traits were identified using the phenotypic information for fertility collected on a national basis. Fine mapping of these QTL let to their introduction in 2008 in genomic evaluation and the routine selection for fertility traits in breeding schemes. This approach will evolve in the near future through the inclusion of results of several genomic research programs that were conducted either in station or under field conditions aiming at identifying genes and pathways controlling cattle fertility (based on genomics, transcriptomics and proteomics) and at enhancing phenotyping for reproductive performance. The paper describes the general approach behind these evolutions, the expected benefits of genomic selection and first results. Information on the potential use of reproductive technologies that may improve the efficiency of multiple trait genomic selection are also presented.