Association of polymorphism within LTF gene promoter with lactoferrin concentration in milk of Holstein cows

This study analyzed the association between single nucleotide polymorphism (A/C) in position -28 located in the TATA box of LTF gene and the lactoferrin concentration in bovine milk secreted by healthy and infected udders. Out of 241, 69 cows were selected into the experimental group and were divided into 3 groups according to mean value of somatic cell count (SCC): I <180 000 cells/mL, II: 180 000 - 350 000 cells/mL and III > 350 000 cells/mL. In each SCC group, three LTF genotypes: AA, AC and CC were identified by PCR-SSCP method. A total of 604 milk samples were collected monthly and lactoferrin concentration was measured by ELISA. The 1-way ANOVA within SCC groups was performed to estimate association of -28 A/C genotypes with mean lactoferrin concentration per lactation. In the group of healthy cows (<180 000 cells/mL) LTF concentration in milk cows with the AA genotype (107.58 +/- 17.92 mu g/mL) was significantly higher than in homozygotes CC (52.09 +/- 19.01 mu g/mL). Unexpectedly, in cows with elevated SCC (>350 000 cells/mL) we observed a significant opposite relationship (207.21 +/- 28.50 in CC vs 115.0 +/- 28.6 mu g/mL in AA). We hypothesized that a promoter with allele C, which cannot be recognized as a TATA sequence is becoming more accessible for other transcription factors, which may induce alternative LTF gene expression. We assume that our results demonstrate a very interesting effect of differential gene expression depending on polymorphism in a key regulatory motif (TATA box) and also on the health status of mammary tissues.