A single nucleotide polymorphism in the coding region of bovine transferrin is associated with milk fat yield.

The bovine transferrin gene (TF) is located at 125 cM on bovine chromosome 1 (BTA1); it codes for transferrin, a glycoprotein that is highly conserved in many species and that is responsible for iron transport. The TF gene has been located in several QTL regions, and some transferrin classes have been associated with fat and milk yields. We analyzed by means of allele-specific oligonucleotide real-time PCR the c.1455A>G SNP in exon 12 of the TF cDNA sequence (accession number U02564), which induces an Asp/Gly substitution at position 469 of the peptide. The c.1455A>G SNP was assayed in eight Spanish cattle breeds, as well as in two groups of Holstein-Friesian animals that had the highest and lowest estimated breeding values for milk fat yield. Analysis of the cSNP showed balanced frequencies in all breeds, with a mean of 0.44. Evaluation of a potential association between the cSNP and the groups of Holstein-Friesian animals selected for milk fat yield showed a significant association (P < 0.0006); the G allele was associated with high fat production. Significant differences in genotypic frequencies between the groups were also detected (P < 0.0028). These results lead us to suggest that the TF gene has an effect on milk fat yield.