The highest peak in the latter region corresponded to Hapmap43045-BTA-76998, which was associated to αS2-CN and mapped in close proximity to several genes involved in immune system response, e.g., 0.2 Mb from IL8, 0.1 Mb from CXCL6 and 64 Kb from PPBP. IL8, for instance, is a highly polymorphic gene considered to be a mastitis trait34 and may also be a quantitative trait locus (QTL) for milk production traits35,36. This evidence concerns the gene CXCL6 and mastitis.