Plant & Animal Genomes XVI Conference

January 12-16, 2008
Town & Country Convention Center
San Diego, CA

Identification Of Genes Involved In Milk Composition

Marleen H.P.W. Visker , Patrick D. Koks , Anke Schennink , Jan J. van der Poel , Martien A.M. Groenen , Johan A.M. van Arendonk

  Wageningen University, Animal Breeding and Genomics Centre, P.O. Box 338, 6700 AH, Wageningen, The Netherlands

The Dutch Milk Genomics Initiative aims at the identification of genes involved in natural genetic variation in milk properties, in particular milk-fat and milk-protein composition. DNA and milk samples have been collected from a population of 2000 Holstein Friesian cows in first lactation: 1000 cows descend from five proven sires and 1000 cows descend from 50 young bulls. This design enables estimation of genetic parameters (heritabilities and genetic correlations) as well as detection of QTLs and finemapping. Milk samples have been analyzed in detail, resulting in routine milk recording data (milk, fat and protein yield, fat and protein percentage), protein composition (all major milk proteins), and fat composition (individual fatty acids). Identification of genes is performed simultaneously via a candidate-gene and a genome-wide approach.
DGAT1 was identified as a candidate-gene, because of its effects on milk-fat percentage. Our study reveals that the K232A polymorphism in DGAT1 has significant effects on fat composition as well. For the whole genome scan the selection of 1000 Holstein Friesian cows descending from five proven sires has been genotyped for 1500 SNPs. Genetic maps have been made, facilitating the ongoing identification of QTLs for a large number of milk traits.
Our results will enable marker assisted differentiation and maker assisted selection by the breeding and dairy industry, in order to optimize milk quality and to develop innovative dairy products.