Characterisation of single nucleotide polymorphisms identified in the bovine lactoferrin gene sequences across a range of dairy cow breeds

Abstract

The lactoferrin gene sequences of 70 unrelated dairy cows representing six different dairy breeds were investigated for single nucleotide polymorphisms to establish a baseline of polymorphisms that exist within the Irish bovine population. Twenty-nine polymorphisms were identified within a 2.2 kb regulatory region. Nineteen novel polymorphisms were identified and some of these were found within transcription factor binding sites, including GATA-1 and SPI transcription factor sites. Forty-seven polymorphisms were identified within exon sequences with unique polymorphisms that were associated with amino acid substitutions. These included a T/A SNP, identified in a Holstein Friesian animal, which resulted in a valine to aspartic acid substitution (Val89Asp) in the mature lactoferrin protein. Other SNPs of interest were associated with amino acid substitutions in the lactoferricin B peptide sequence and an A/G SNP, identified in a Jersey animal, was associated with a tyrosine to cysteine change (Tyr181Cys). The polymorphisms identified in the promoter region may have implications relating to lactoferrin expression levels in cows and those identified in the coding sequence indicate the existence of protein variants in the Irish bovine population. The data presented in this study emphasises the potential for lactoferrin to serve as a candidate gene to select for mastitis resistance with the aim of improving animal health.