Role of K on Rumen Fermentation and Milk Fat Synthesis

Diet-induced milk fat depression (MFD) continues to have major economic impact in the dairy industry and a priority for finding solutions. Current thinking links MFD with the formation of bioactive trans fatty acid intermediates produced from biohydrogenation of unsaturated fatty acids by the rumen microbial population. The most potent biohydrogenation intermediates linked to MFD include several conjugated linoleic acid (CLA) isomers. Formation of these CLA isomers has been associated with several dietary risk factors including source and amount of grain, source and amount of fat, fiber source, and animal management factors. Solutions to solving MFD are complicated by interactions that often exist among two or more risk factors, making the process of reversing MFD often times slow and frustrating. Ideas and discussion has turned to the possibility of dietary supplements that might reverse accumulation of the undesirable CLA that are linked to MFD and speed return of milk fat % back to normal. Recent studies with lactating cows showed improvement in milk fat percentage following addition of K supplements to the diet, suggesting that K might act as a biohydrogenation normalizer. Results from several continuous culture experiments will be reviewed briefly to examine the role of K in influencing CLA formation and their possible role in alleviating MFD.