MAPPING QTL IN THE BROWN SWISS BREED FOR MILK QUALITY TRAITS

Mastitis is a multifactorial infectious disease, mainly caused by bacteria that infect the mammary gland. It is one of the major diseases in dairy ruminants, with respect to industry and public concern, economic impact, and animal welfare. The high genetic correlation of Somatic Cell Count (SCC) and bacterial infection described in many studies and the availability in most countries of SCC data routinely recorded within the milk recoding system, have lead the suggestion to use SCC in selection against udder infection and to incorporate selection for lower SCC content in the overall selection indexes for dairy cattle. Objective of this study is to map QTL for SCC in the Italian Brown Swiss breed population using a selective DNA pooling design with Single Marker Mapping (SMM) and Multi Marker Mapping analysis (MMM). This will be the first complete SCC QTL mapping in this population and will serve as base information for further confirmation studies using dense marker chip design.