Genome Wide Analysis of Milk Fatty Acid Profile and Coagulation Properties in Italian Brown Swiss Cows using a Low Density SNP Panel

Milk composition and technological properties are of great importance for the dairy cow industry. A sample of 309 Italian Brown Swiss cows was genotyped using the Illumina 3K SNP beadchip. After edits 2,683 markers were retained for further analyses. Records for milk fatty acid profile and coagulation properties were analysed with a mixed linear model that included the fixed effects date of the test, herd, parity, calving season, stage of lactation and SNP and a random effect of the sire. SNP with a level of statistical significance <0.01 were then shuffled 10,000 times and the 1% of values were retained and used to construct a new corrected level of significance in order to account for multiple testing. Several markers were found to be associated with the considered traits. In the case of the cis9 trans11 CLA, for example, four SNP resulted statistically significant: two of them were located on BTA22 at approximately 44Mbp. A significant marker on BTA22 was also found for omega 3 fatty acids at 49Mbp. Two markers located on BTA9 were identified for curd firming time.