Polyunsaturated Protected Lipid: Effect on Milk Phospholipids

Abstract

Five lactating Holsteins were fed a complete mixed control ration for 20 days, sunflower-soybean protected lipid supplement for 28 days, and finally control for another 20 days. Total milk phospholipid and milk fat produced per day increased during protected lipid feeding, whereas milk produced per day remained the same throughout the study. Digly cerides from fresh milk had larger amounts of polyunsaturated fatty acids during protected lipid feeding. In contrast to milk diglycerides, there was little change in fatty acid composition of milk phospholipids in response to the protected lipid diet. Independence of bovine milk phospholipid fatty acid composition from influence of dietary fatty acid composition is important to the understanding of mammary fat synthesis. Stability of fatty acid composition in bovine milk phospholipids sharply contrasts with changes in milk diglycerides and triglycerides.