Mediterranean River Buffalo CSN1S1 gene: search for polymorphisms and association studies.

The aim of the present work was to study the variability at CSN1S1 locus of the Italian Mediterranean river buffalo and to investigate possible allele effects on milk yield and its composition. Effects of parity, calving season and month of production were also evaluated. Three SNPs were detected. The first mutation, located at position 89 of 17th exon (c.628C>T), is responsible for the amino acid change (p.Ser178Leu). The other two polymorphisms, detected at the positions 144 (c.882G>A) and 239 (c.977A>G) of 19th exon respectively, are silent (3’ UTR). Associations between the CSN1S1 genotypes and milk production traits were investigated using 4,122 test day records of 503 lactations from 175 buffalo cows. Milk yield, fat and protein percentages were analyzed using a mixed linear model. A significant association between the c.628C>T SNP and the protein percentage was found. In particular, the CC genotype showed an average value of about 0.04% higher than the CT and TT genotypes. The allele substitution effect of the cytosine into the thymine was -0.014, with a quite low (0.3%) protein percentage (PP) contribution on total phenotypic variance. A large dominance effect was detected. Furthermore, a characterization of the CSN1S1 transcripts and a method based on MboI-ACRS-PCR for a rapid genotyping of c.628C>T were provided.