Interrelationships Between Milk Carnitine and Blood and Milk Components and Tissue Carnitine in Normal and Ketotic Cows

The carnitine concentration in milk was determined weekly for two groups of 19 cows (one group kototic and one control) during the first 8 wk of lactation.Milk carnitine concentration was high at the start of lactation in both groups and decreased about half by the 8th wk.Carnitine concentration in miLk from ketotie cows was correlated with blood glucose --.41, acetoacetate .39,fi-hydroxybutyrate .48,free fatty acids .26,milk fat .70,protein --.47, and lactose --.51.In the control group carnitine and milk protein were the only variables with significant correlation --.28.Carnitine concentrations in tissues of dry and lactating cows did not differ with lactation or stage of lactation.One ketotic cow had skeletal muscle carnitine coneentrations higher than controls; however, the most pronotmeed difference was a threefold elevation of blood camitine.These changes in camitine concentration in milk and tissue are discussed in connection with knowledge of carnitine biosynthesis and turnover.Elevated camitine excretion in milk during ketosis results from increased earnitine synthesis.