Analysis of the β-lactoglobulin locus using the grand-daughter design in the Canadian Holstein population

A total of 185 informative sons from nine heterozygous grandsires were used to study the associations of alleles A and B of the β-LG locus and milk production using the granddaughter design. The average informativeness of the β-LG locus for the nine heterozygous grandsires was 61%. The β-LG locus was found to be significantly associated with milk protein percentage (P ≤ 0.05) across families and (P ≤ 0.01) in one family. The A allele was associated with higher protein percentage EBV (0.096%) than the B allele in that family. There was no association between β-LG and other production traits (milk, fat and protein yields and, fat and percentages). The β-LG locus has a potential use in marker-assisted selection. However, since the association between markers and a given trait is not found in all families, within-family marker selection might be more appropriate due to linkage disequilibrium. Key words: β-lactoglobulin, Canadian Holstein, milk production traits, granddaughter design