124. The Metabolism of Betaine and Allied Tertiary Nitrogenous Bases in the Ruminant

Abstract

In the ruminant, the main tertiary nitrogenous metabolite of all the tertiary nitrogenous bases examined is trimethylamine oxide. Small traces of trimethylamine and insignificant traces of mono- and dimethylamine also occur in cow's urine. The nitrogen of simple bases (trimethylamine and trimethylamine oxide) is almost quantitatively and rapidly excreted as trimethylamine oxide. With betaine, choline and the methyl ester of dimethylaminoacetic acid, only from 14 to 43 per cent, of the nitrogen is excreted as trimethylamine oxide, the amount so excreted depending on the level of nitrogen intake, the nature of the base fed and the degree of accommodation of the animal to the base fed.The rates of excretion of the tertiary metabolite show well-defined peaks depending on the nature and amount of the base fed. The feeding of 100 g. of betaine would show a peak of excretion at about 4½ hours after feeding. The importance of the time interval between feeding and milking is discussed from this aspect. No unchanged betaine was be detected in the urine.