Overview of Fat Digestion and Metabolism in the Lactating Dairy Cow

摘要

The mammary gland has an incredible level of organization and a remarkable ability to convert circulating nutrients into milk components. This review highlights four areas of high interest in the biology of milk synthesis where advances over the last quarter century have resulted in new understanding and/or revealed new opportunities.First, advances in our understanding of the mechanisms of milk secretion has led to a substantial increase in our knowledge of the intracellular origin of lipid droplets and the identity and potential function of milk-fat-globule membrane proteins in milk-lipid secretion. Second, the concept of genetic engineering and the use of animals as 'bioreactors' and the 'pharming' of proteins not normally found in milk has gained recognition, and this limited use of lactating dairy cows offers promise. Third, recent breakthroughs have advanced our understanding of the nutritional regulation of milk fat and highlighted the interrelations between dietary components, digestive processes in the rumen and the regulation of mammary synthesis of milk fat. Finally, nutritional quality is becoming increasingly important in food choices because of consumer awareness of the link between diet and health. The traditional nutritional value of milk and dairy products is well established, but recent discoveries have identified a number of 'bioactive' components in milk with potential to improve human health. This discussion will importantly emphasize that dairy products are an excellent source of nutrients for the human population. These latter two areas will be the major focus of this review. Overall, recent discoveries in the biology of milk synthesis represent exciting opportunities and the dairy industry is ideally suited to take advantage of advances in these areas.