PSXI-3 - Genome-wide association study for MIR-predicted milk fatty acids composition in Russian Holstein cattle population

Milk fatty acids (FA) derived from infrared spectra are a new type of traits that allow fast and predictability use their in dairy breeding and herd cattle management. The Holstein animals feature are the high milk yield, but milk composition traits can be different according to population or country origin. The purpose of our study was to find out genetic variation for milk FA and detect QTLs associated with Holstein sires’ EBV in Russian cattle population. For this analysis, we used an experimental dataset for 36982 milk test records from 14 breeding herds in the Moscow region. Individual milk samples per animal analyzed routinely by MilkoScan7 for different FA types: C14:0, C16:0, C18:0, C18:1, saturated, mono- and polyunsaturated, short-, medium- and long-chain. Total number of bulls consisted 778 individuals including 222 animals with genotypes (39051 SNP, Illumina 50K). For calculating EBV by Sire Model, we applied BLUPF90. Plink 1.90 performed quality check control and GWAS procedure. Heritability coefficients were 0.071-0.155 for C14:0-C18:0 levels, 0.196 for C18:1, 0.083 for SFA, 0.018 for PUFA, 0.176 for MUFA, 0.114-0.155 for SCFA-LCFA levels. GWAS revealed most significant (P < 0.001-0.00001) frequently QTLs associated with FA content that were cited in articles previously for BTA5 (CHST11,C18:1), BTA6 (KCNIP4,C18:1; PPRAGC1A,C18:0), BTA11 (NRXN1,LPIN1,C18:1; NBAS,C18:0), BTA26 (PCDH15,PUFA; PRKG1,C18:1). These genes were responsible for synthesis milk fat, fertility, udder conformation traits, lauric, myristic, myristoleic, palmatoleic, oleic and other types of FA. In addition, we identified several QTLs for C14:0, C16:0, SFA, MUFA, SCFA, LCFA on BTA1 (137.32 Mb), BTA10 (5.50 Mb, 9.79 Mb), BTA14 (44.35 Mb), BTA19 (17.57-17.89 Mb) and BTA22 (14.02-14.06 Mb, 20.29-20.45 Mb). Our results are the first steps toward to understanding genetic and genomic mechanisms for using FA in selection processes to improve milk quality for Holstein cattle in Russia. The study was funded by RSF (project No.21-76-20046)