Effect of Infusion of Carnitine and Glucose on Blood Glucose, Ketones, and Free Fatty Acids of Ketotic Cows

Carnitine was infused into control (midlactation), feed-restricted ketotie and spontaneously ketotic cows. Blood glucose, acetoacetate, fl-hydroxybutyrate, and plasma free fatty acids were determined. DL-Carnitine infusion into control animals had no effect upon blood glucose or ketones nor did it affect nfilk yield or composition. DL-Carnitine infusion into spontaneously ketotic cows gave variable results. Infusion at 20 micromoles (3.9 rag) DL-carnitine per kilogram per hour caused blood glucose to rise and ketones to fall in three cases; in a fourth case blood ketones rose and glucose fell. A single case treated with 145 t~moles L-carnitine (28.6 mg) per hour per kilogram increased acetoacetate accompanied by decreased plasma free fatty acids, whereas glucose showed only a transient elevation. L-Carnitine infusion into feed-restricted and spontaneously ketotic cows was consistent only in lowering plasma free fatty acids. Glucose infusion into feed-restricted ketotic cows increased blood glucose and decreased blood acetoacetate; however, plasma free fatty acids were unaffected. Glucose infusion into a spontaneously ketotic cow immediately decreased plasma free fatty acids. Fatty acid metabolism in the ketotic cow did not function at peak efficiency and effects of carnitine infusion were the result of increased fl-oxidation of long-chain fatty acids.