Australian Milk Fat - Seasonal and Regional Composition of Fatty Acids

Abstract

Regional and seasonal differences in milk fat composition affect the human nutritional properties of milk. Milk from 19 bulk production sites across Australia were collected on a monthly basis for 2-years in 1994-1995 and analysed for Fatty Acid (FA) composition. Considerable site and seasonal differences were encountered with the analysis revealing clear seasonal variation in the abundance of short chain saturated FAs, the minor unsaturated FAs, C16:0, and the long chain unsaturated FAs. The magnitude of difference varied with geography, with generally less variation observed in the Queensland, New South Wales and South Australian regions. Positive correlations were measured between the short chain FAs from C4 to C14, diminishing with the increased difference in chain length. Correlations between saturated and mono-unsaturated FAs of the same chain length were mostly positive for C16 and C18 however generally not for C10 and C14, indicating fundamental differences in desaturase activities for different carbon chain lengths and between regions. These results provide useful information that can be used by the Australian domestic and export dairy industry to understand and pre-dict the effect of season and geographical location within Australia on the abundance of FAs of nutritional importance.