Assessment of milk quality using novel mutations of B2M gene in bovine DNA from milk

Abstract

This study investigated the expression of novel mutations of the β2-microglobulin (B2M) gene in bovine genomic DNA isolated from milk-borne leukocytes and tested the association of these mutations with milk quality traits in Holstein cows. DNA was extracted using a novel protocol allowing for the amplification of long fragments of DNA isolated from small amounts of unprocessed milk samples. Genomic mutations at the B2M locus were explored by DNA sequencing using specific primers and a cluster of five identified within a 729-bp region of intron 3. Specifically, mutations at 7008(G>T), 7202(A>G), 7432(G>T) and 7437(G>C) were all found to be significantly associated with milk protein percentage (P < 0.05), and a mutation at 7026(G>A) was significantly associated with somatic cell count (P < 0.05). The potential to use these mutations as further tools for the pre-evaluation of milk quality is discussed.