Concepts in Fat and Fatty Acid Digestion in Ruminants

Fat and fatty acid metabolism and digestion in ruminants is of considerable interest at the present time, both to scientists and the agricultural industry. The subject has received renewed interest for a number of reasons; first, the use of dietary fat supplements has increased, and will continue to do so, as nutritionists strive to increase the energy density of diets to meet requirements of the high producing dairy cow, and second, we now recognize that fatty acids, both of dietary and rumen origin, can have specific and potent effects on ruminant metabolism and human health. Increased interest in these areas, and recent improvements in analytical procedures have led to recent efforts to include lipid metabolism in models of ruminant digestion, and if done properly this may potentially be useful in diet formulations and decision making processes and recommendations. Considering the increased interest in ruminant lipid metabolism the purpose of this review is to provide an overview of the biological processes involved in the metabolism of fatty acids in the rumen and the subsequent absorption of fatty acids in the small intestine. To aid our discussion we will refer to a data set that we have recently put together which will allow us to highlight key changes that occur during rumen metabolism and the subsequent digestibility of fatty acids.