Effect of non-protected sunflower oil supplementation on milk fatty acid profile and oxidative status in Simmental cows

Abstract. Milk production, milk composition, milk fatty acid profiles, and antioxidant status of Simmental cows supplemented with non-protected sunflower oil were studied. Ten Simmental cows in mid-lactation were appointed for change over feeding trial with one of the diet applied: the control (WSO) diet consisted of 26 % corn silage, 33 % perennial ryegrass haylage, and 41 % concentrate in dry matter (DM), and the experimental diet (SO) consisted of control diet supplemented with 2 % of unrefined sunflower oil per cow and day. The cows were kept in indoor housing system with feeding and milking system two times daily and ad libitum water supply. The milk production and standard milk components remained unchanged during the study. The partial modification of fatty acid composition was remarked with the significantly higher linoleic and conjugated linoleic acid (CLA) (cis-9, trans-11 C 18:2) concentration and significantly lower palmitic acid during the SO treatment. The blood gluthathion peroxidase (GPx) activity significantly increased and the thiobarbituric acid reactive substances (TBARS) concentration decreased significantly in the SO treatment.

The non-protected sunflower has a perceptible effect on the milk fatty acid composition in Simmental cows of our research. The lower index of lipid peroxidation and higher GPx activity in blood of cows during the SO treatment could be a consequence of the antioxidant components that are normally present in the unrefined vegetable oils. The enzyme activity reflects appropriate functioning of the antioxidant defence of cows that emphasise importance of well balanced diet during the unsaturated fatty acid supplementation.