Digestibility of cow's tritiated milk powder by calf and pig

Milk obtained from a lactating cow, maintained in a byre and fed on tritiated drinking water (266 μCi/1), was used in these experiments. Tritium moves into the different metabolic pathways that eventually produce milk. After administration of this continuous oral dose of tritiated water, the tritium content of the whole milk and of the dry matter reaches a plateau 10 days after the beginning of the ingestion of THO. Analysis of the radioactivity in the several milk constituents indicated that tritium was incorporated to different extents in different components. This in vivo tritiated milk powder was fed to two calves and three pigs in their rations. Daily samples of faeces were taken. For determining the digestibility and the incorporation of this milk powder the animals were slaughtered and several organs examined. The tritium activity was determined in the dry matter of the organs and the faeces. The data obtained in these experiments indicate that the milk powder is better absorbed by the calf if the digestibility coefficient is taken into consideration, but the milk powder is better incorporated in the organic matter of the muscle and liver of the pig. (author)