Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

A map of QTL affecting milk production traits in the Brown Swiss

A selective DNA pooling approach using milk samples was adopted to map QTL affecting milk yield (MK) and milk protein percentage (PP) in the Austrian, German, and Italian Brown Swiss dairy cattle populations. The scan was based on 139 markers evenly spaced on the genome. The mapping population consisted of half sib daughter families of 10 Brown sires with 1000 to 3600 individuals. Three families were sampled in Germany, three in Italy, one in Austria while the sampling for three sires occurred jointly in Austria and Italy.

No complete genome scan for productive traits was available in the Brown breed before this project, as no marker association with secondary traits (namely protein and fat yield, fat percentage and milk somatic cell count).

The markers resulted significant were 19 for PP, 29 for MK and 80 for both traits. Over the 840 sire x marker combinations 153 and 137 were significant for PP and MK respectively and 62 for both traits. Over the significant combinations for one or both the traits, MK and PP showed the same direction of the effect in 201 cases and opposite effect in 228 instances.

Among the QTLRs that showed a significant effect for PP and/or MY, five were chosen for more intensive study, located on BTA03, BTA11, BTA13, BTA14, BTA20. The proximal part of BTA14 is known to house DGAT1, a QTL with strong effect on FY and MY. The QTL segregating in some of the informative families confirmed the existence of the gene. In the Brown breed it seems that a second QTL region on BTA14 affecting both MY and PP can be identified between 70 and 110 cM.

Generally secondary traits tested show sire/marker significance with several QTL identified for MY and PP, while for milk somatic cell count there is fewer evidence of correlated effect at same location.

Main society interested in results are farmers and breeders of the Austria Germany and Italy. Dissemination of results was guaranteed thanks to seminars and round tables to farmers organization in Italy and in Austria. Articles for extended farmers audience have been produced and will be published in sector journals
Results on main and secondary traits arising from the BovMAS project allow the potential use of QTL knowledge in ongoing selection strategies.

New knowledge in the Brown dairy cattle population, open the possibility to enhance the breeding programs to new technologies and to deeper investigate in the close future the existence and the effects of genes related to economic traits in targeted genome regions, building up to existent know how.

The produced knowledge is ready to be integrated into the ongoing breeding schemes towards the application of technologies and skills developed in the project:
- Sampling of DNA from milk embedded in the ongoing national milk recording schemes;
- Genotyping at routine level to be carried out by breeders/farmers service labs;
- Integrating information from targeted QTL regions in genetic evaluations routinely from breeders organization. Benefits arising from a prompt application of QTL knowledge using within family MAS reside in paving the way to gene assisted selection as soon as information will became available.

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