The Lipid Composition of Milk as Affected by High Grain-Limited Roughage Rations Containing Whey Products

Certain rations fed to lactating dairy cows appear to have a dramatic influence on the lipid composition of milk fat produced. A high grain ration fed with a limited amount of roughage tends to cause a depression in milk fat production while at the same time changing the milk fat composition. There have been various attempts to alleviate the depression in milk fat. Minerals used in the ration seem to slightly relieve the milk fat depression caused by high grain rations. One drawback has been lower milk production due to a decline in concentrate consumption. Whey products added to a high concentrate ration produced more acceptable results. The milk fat production was returned nearly to normal without altering total milk production. Previous research has been involved with the gross composition of milk and the fatty ac id composition of the milk fat. Changes have been shown in the fatty acid composition of milk fat when cows were fed high concentrate rations. These changes may be responsible for flavor problems, such as a decreased oxidative stability of the milk. In light of this, the lipid composition of milk is of economic importance to the dairy industry. The purpose of this research was to determine changes that occur in the lipid composition of milk obtained from cows on high grain limited roughage rations containing whey products. The specific objectives of the study were: 1. To compare the phospholipid content of the milk fat in the standardization period to that during the experimental period. 2. To determine the total fatty acid composition of the milk fat in the standardization and experimental periods. 3. To determine the fatty acid composition of the polar lipid fraction. 4. To measure gross changes in the polar lipid components