Comparison of milk protein allele frequencies in Nordic cattle breeds

Allele frequencies at four milk protein loci were studied in five modern an d 17 old Nordic cattle breeds in order to reveal variants that are characte ristic for these populations. The B allele of CSN3, which has been associat ed with improved manufacturing properties of milk, showed significantly low er frequencies in modern production breeds than in old breeds of interest f or conservation purposes. Characteristic frequencies of CSN1S1 (C), CSN2 (A 2) and CSN3 (B) were found in Icelandic cattle, Swedish Mountain cattle, No rthern Finncattle and Western Fjord cattle, which indicate a common origin of these populations. Further comparisons of allele frequencies in old Nord ic breeds suggest sorting of these breeds into two groups with a northern a nd southern geographic location.