Abstract: In order to evaluate the influence of season on the fatty acid content of Holstein cow milk in Inner Mongolia, milk samples were collected from 10 large commercial pastures in Inner Mongolia during four seasons (spring, summer, autumn and winter) and analyzed for fatty acid content by gas chromatography (GC). The results showed that: 1) the major fatty acids in Holstein cow milk from Inner Mongolia were palmitic acid, oleic acid, stearic acid, myristic acid and linoleic acid, which did not change due to geographical regions, cow breeds, feeds and processing methods; 2) the proportions of saturated, monounsaturated and polyunsaturated fatty acids in the total fatty acids in cow milk were stable, and so were short-chain, medium-chain and long-chain fatty acids, which was not significantly affected by geographical regions; 3) the major fatty acids in cow milk presented the same trend with season, being at higher levels in spring and at lower levels in summer and autumn; 4) the contents of saturated and polyunsaturated fatty acids differed significantly (P < 0.05) between summer and the other seasons and were lowest in summer, and the content of monounsaturated fatty acids differed significantly (P < 0.05) between spring and summer and were also lowest in summer; and 5) the contents of short-chain and medium-chain fatty acids which have a strong influence on the flavor of milk fat differed significantly (P < 0.05) in summer and autumn compared to the other seasons. This study may provide reliable technical support for product innovation in the dairy industry and the improvement of milk nutritional value.

Key words: seasons; Holstein milk; fatty acid; dairy product analysis; gas chromatography