POLYMORPHISM IN THE 5'-FLANKING REGION OF THE BOVINE-LACTOGLOBULIN-ENCODING GENE AND ITS ASSOCIATION WITH BETA-LACTOGLOBULIN IN THE MILK

Genomic DNA of 71 cows was analysed with the help of polymerase-chain- reaction-based restriction fragment length polymorphisms of five DNA v ariants within the 5' flanking region (R1,R2, R3, R5, and R14 at posit ions +31, +27, -22, -209, -662 bp from transcription start point +1) o f the bovine beta-lactoglobulin (beta-Lg) encoding gene. Protein varia nts, content and yield of beta-Lg were determined in milk samples of e ach cow. Frequencies of the common alleles varied between 0.52 and 1.0 per breed. One of three different genotype combinations (BB/AA/AA/AA/ AA/AA, AB/AB/AB/AA/AB/AB, and AA/BB/BB/AA/BB/BB for beta-Lg-variant/R1 /R2/R3/R5/R14) was carried by 82% of the cows, so that in populations two haplotypes at a similar frequency can be assumed. Associations bet ween variants in the beta-Lg-encoding gene, and yield as well as conte nt of beta-Lg, were obtained for cows of the genotypes BB/AA/AA/AA/AA/ AA, AB/AB/AB/AA/AB/AB, and AA/BB/BB/AA/BB/BB (least square-means+/-SE) : 91.8+/-6.9 g/day and 10.78+/-0.61%, 140.5+/-10.7 g/day and 13.94+/-0 .86%, and 149.4+/-8.2 g/day and 17.59+/-0.65% respectively. Difference s were p < 0.001. The population data can be explained by the effects of the gene variants on regulation of the expression of the correspond ing gene.