[Effect of feeding rapeseed oil to dairy cows on the fatty acid composition of butterfat].

Butter is rich in lauric, myristic, and palmitic acids which are assumed to be hypercholesterolemic. The replacement of usual dietary fat by rapeseed oil induces a serum cholesterol decrease. The objective of the study consisted in measuring the influence of feeding different amounts of full-fat rapeseed or oil-rich rapeseed cake to dairy cows to improve the fatty acid composition of milk fat. The results demonstrate a significant increase of iodine number and spreadability of butter. The percentage of lauric+myristic+palmitic acid (LMP) decreased by about 18% of whole fatty acids. Stearic and oleic acid increased significantly but the percentage of trans octadecenoic acid increased too. It can be concluded that the special butter has a nutritionally improved fat characterized by an increase of cholesterol-lowering fatty acids (C18 and C18:1) and a decline of cholesterol-elevating fatty acids (LMP).