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Identification of QTL and candidate mutations affecting major milk proteins in three French dairy cattle breeds
A whole genome scan was performed to detect QTL for milk αs1, αs2, β, κ-casein, α-lactalbumin and β-lactoglobulin predicted from mid infrared (MIR) spectrometry. About 8,000 Holstein, Montbéliarde and Normande cows were genotyped mainly with the BovineSNP50® beadchip. A linkage disequilibrium and linkage analysis with 6 SNP-haplotypes revealed 61 to 75 QTL in each breed. Three of these QTL, common to all breeds (BTA6-87Mb, BTA11-103Mb and BTA20-58Mb), were highly significant and explained 16-51% of the genetic variance of protein contents. Very significant QTL were also observed on BTA2, 6, 14, 20 and 29. Concordance analyses, performed between QTL statuses and sequence-derived polymorphisms from 13 bulls, revealed already known causal polymorphisms in LGB (BTA11) and GHR (BTA20) genes whereas novel candidate mutations were proposed on BTA2, 6, 20 and 29. These preliminary results are encouraging for further studies to identify causal mutations.
Keywords:
Dairy cattle
Milk proteins
QTL
