Effect of oils and seeds in ruminant diets on milk fat fatty acid profile. Review

This paper reviews the effect of plant lipids added to dairy ruminant diets on milk fat fatty acid profile. Changes in milk fatty acid profile when oils and oilseeds are added to the diet are broadly similar in cows, ewes and goats. Some of the observed effects are common to all oils and oilseeds whatever the quantitatively main fatty acid (i.e. oleic or linoleic or alpha-linolenic acids) they supply to the diet: butyric acid content does not usually change, medium chain saturated fatty acid content is lowered and unsaturated fatty acid content increases. Oils and oilseeds rich in linoleic acid raise the content of vaccenic, rumenic and trans10-18:1 and increase the n-6 to n-3 ratio in milk fat. Adding linseed oil or linseeds to the diet also increases vaccenic and rumenic acid contents, but does not affect that of trans10-18:1 in milk fat and lower its n-6 to n-3 ratio. As a conclusion, including oils and oilseeds into dairy ruminant diets widely modifies milk fat fatty acid profile. Best results from human health point of view are obtained adding linseed oil or linseeds to the diet.