Abstract
Fatty acid binding proteins FABP3 and FABP4 act as intracellular lipid chaperones that influence fatty acid transport and metabolism in mammary tissue, and genetic variation in these genes may affect milk composition. We examined the associations between FABP3 and FABP4 polymorphisms and milk composition and fatty acid profiles in 200 lactating Native Southern Yellow (NSY) cows. DNA from each cow was PCR-amplified and Sanger-sequenced for FABP3 and FABP4; genotypes were tested for their association with milk fatty acid concentrations and standard composition traits using linear models adjusted for relevant covariates. We detected a missense variant in FABP3 (c.3656G > A; p.Val45Met) and an intronic SNP in FABP4 (g.3509T > C). The FABP3 p.Val45Met AA genotype was associated with higher concentrations of butyric, palmitic, oleic, and α-linolenic acids. Cows with the FABP4 TC genotype exhibited elevated levels of myristoleic, γ-linolenic, conjugated linoleic, and arachidic acids, along with increased fat-free dry matter, protein, and lactose. In silico analyses provided mixed evidence for the structural effects of p.Val45Met, molecular docking suggested altered ligand affinity for several fatty acids, and splice site prediction implicated g.3509T > C in possible transcript processing changes. These variants constitute candidate markers for milk fatty acid composition in NSY cattle; replication in independent cohorts and functional validation are recommended to confirm their utility for milk quality improvement.