Summary:Irradiated sperm typing will be developed for high-resolution determination
of evolutionary breakage points between humans and cattle. A particularfocus will be put on bovine chromosome 6 (BTA6), where several putativequantitative trait loci (QTL ) have been localised for mastitis resistanceand milk production in the Norwegian Cattle population. Furthermore,transcript profiling by DNA-microarray technology will be used to identifydifferentially expressed genes that maps to the chromosome interval ofinterest. The ultimate goal is molecular characterisation of the genesunderlying the QTL for mastitis resistance. The results of this project caneasily be put into practice by marker or gene-assisted selection. On thelong term this will reduce the inci dences of mastitis, cut the number ofantibiotic treatments, and improve the animal welfare of Norwegian cows.