Effect of Feeding a Milk Fat Depressing Ration on Fatty Acid Composition of Blood Lipids

Abstract

The feeding of high-grain, low-roughage rations to lactating cows not only causes a marked reduction in the fat content of the milk produced, but causes major changes in the fatty acid composition of the milk fat. The most significant change noted is a decrease in stearic acid with a concomitant increase in oleic and linoleic acids. In this study it was found that the fatty acid composition of blood lipids showed similar changes in fatty acid makeup as found in the milk fat, e.g., a decrease in stearic acid and an increase in the unsaturated homologs. It is believed that an understanding of the principle causes for the change in the fatty acid composition of the blood lipids is basic to explaining the production of low-fat milk when high-grain rations are fed to dairy cows.