CHANGES IN BOLA CLASS-I ALLELE FREQUENCIES OVER YEARS IN NORWEGIAN BREEDING BULLS, AND THE ASSOCIATION OF BOLA WITH PERFORMANCE TRAITS IN YOUNG BULLS

Class I bovine lymphocyte antigens (BoLA) were typed in Norwegian Catt le (NRF) breeding bulls over a twelve-year period, together with a rec ent one-year batch of young bulls. Significant increases in the freque ncy of BoLA w16 and A30, and a decrease in the frequency of A13, were found for the breeding bulls. The gene frequency of w16 exceeded 0.27 in latter years, which is higher than that reported for other breeds. BoLA typing results were associated with the young bulls' own performa nce test results for growth rate, conformation and semen quality. Ther e was a statistically significant interaction effect of BoLA A8 and A1 0(w50) on growth rate. Animals carrying w25 had a significantly increa sed conformation score, while animals carrying A30 had a statistically significant decrease in the same trait. Significant negative associat ions of both A11 and A30 with semen characters were found. No signific ant associations of w16 with these performance traits were revealed.