Showing papers by "Didier Boichard published in 2010"

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

Abstract: 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.

Where is Dairy Cattle Breeding Going? A Vision of the Future

Abstract: Genomic selection in dairy cattle breeding is a breakthrough such as the industry has not experienced since progeny test. It will have marked consequences on genetic evaluation methodology but also, and more deeply, on the organization of breeding schemes, on expected genetic gain and relative weight of traits in breeding objectives, on the nature and distribution of some related activities such as performance recording, on the structure of breeding companies and on the emergence of new actors. Multi-breed management of selection could make it possible to share reference populations and to save resources and money. Genomic selection opens new opportunities to improve functional traits and to meet new environmental and/or societal requirements, and probably to differentiate competitors via inclusion of specific and original traits. Very large reference populations offer a unique opportunity to elucidate the genetic determinism of many traits, even complex. In the longer term, big challenges are prediction of interactions between genes, prediction of genotype x environment interactions and adaptation to particular environmental conditions. The appropriate conditions using of genomic selection should be carefully studied in developing countries, because their environment is strongly different from developed countries and because accurate phenotypes are difficult to obtain on a large and reliable scale. This paper will review some of these topics.

Mise en place de la Sélection Génomique dans les trois principales races françaises de bovins laitiers

Abstract: La disponibilite en France de larges populations de taureaux testes sur descendance et genotypes sur la puce « BovineSNP50 ® » d'Illumina dans les trois principales races de bovins laitiers (Holstein, Montbeliarde et Normande) et les travaux de recherche menes dans le cadre du projet AMASGEN ont permis la mise en place d'une selection genomique en juin 2010 sur l'ensemble des caracteres evalues en selection classique. La methodologie retenue en France est une evaluation BLUP-QTL integrant plusieurs centaines de QTL (Quantitative Trait Locus) par caractere, les plus importants d'entre eux (a effets forts) etant detectes a l'aide d'analyses LD-LA (Linkage Desequilibrium-Linkage Analysis) et les autres, les plus nombreux (a effets faibles) etant detectes par une approche statistique appelee EN (Elastic Net). Des travaux de validation menes sur 1310 taureaux Holstein, 343 taureaux Montbeliards et 320 taureaux Normands montrent que la selection genomique est plus efficace que la selection classique. Les coefficients de determination (CD) des index genomiques de jeunes animaux sont compris entre 0,50 et 0,70 permettant une selection efficace des leur plus jeune âge. Si elle est bien utilisee, tant sur la voie mâle que sur la voie femelle, la selection genomique doit permettre d'augmenter le progres genetique, en particulier sur les caracteres faiblement heritables, sans consequences nefastes sur la variabilite genetique.

Evolution des objectifs et des méthodes de sélection des bovins laitiers

Abstract: Over the last decades, the dairy stock has undergone major changes, and the selection of dairy cattle has become an internal business.With current prospects of milk quota removal, falling prices, increasing herd sizes, changes in the farmers’ way of working and diversification of demand, the ideal cow of the future will have to demonstrate autonomy, robustness and feed efficiency, and will have to produce a rich milk whose composition meets the requirements of humans. Selection methods will change radically with the ongoing development of genomic selection. Animal identification, pedigree and performance recording will remain, but progeny testing of bulls will diminish. Resources will be pooled between research and supervision organisations, breeding companies and other operators, and there will be an increased need for training.