The bonds between the glycerol and the fatty acids are broken down to give rise to glycerol and three fatty acids. Some fatty acids are used by bacteria for the synthesis of phospholipids that are needed to build cell membranes. Another important action of ruminal microbes is to hydrogenate unsaturated fatty acids. During hydrogenation, a fatty acid becomes saturated because a double bond is replaced by two hydrogen atoms. Free fatty acids in the rumen tend to attach to feed and microbial particles and impede normal fermentation, especially of fibrous carbohydrates.
Unsaturated lipids have a more negative effect than saturated lipids.
The seed coat tends to protect lipids within the seeds and make them less rapidly accessible for ruminal hydrolysis compared to free oil. These secretions are essential to prepare the lipids for absorption by forming water miscible particles called micelles that can enter the intestinal cells. In contrast to most nutrients absorbed from the gastro intestinal tract, the absorbed lipids enter the general circulation directly and are used by all body tissues without a preliminary processing by the liver. Overview of lipid metabolism in dairy cows. About half the fat in the milk is derived from the uptake of fatty acids by the mammary gland.