Coprophagy and vitamin B12 in the rat
British Journal of Nutrition
The importance of coprophagy in nutritional studies has long been recognized; already in the early days of vitamins numerous workers demonstrated the presence of B vitamins in the excreta of birds and mammals (cf. Kon, 1945; Elvehjem, 1948; Mickelsen, 1956) and began keeping experimental rats on screens to prevent their consuming their droppings. Rats kept in this way have been used for assays of members of the vitamin B complex and have shown characteristic signs of deficiency in the absence
... cy in the absence of any one of them. However, additional measures have usually been necessary to cause rats to exhibit deficiency of biotin, folic acid or vitamin B" . These vitamins are needed in only small amounts by the rat and are synthesized in appreciable quantity by many micro-organisms. It has been generally assumed that sufficient biotin and folic acid were synthesized and absorbed from the caecum to supply the animals' requirements, for the appropriate deficiency could be induced when synthesis was depressed by the inclusion in the diet of sulphonamide drugs (cf. Animals Male albino rats were reared on a stock diet until about 140 g in weight. Then for 1-14 days before each experiment they were housed individually in cages with raised &in. wire-mesh screens and were given ad lib. a diet containing goo/, a-protein (an isolated soya-bean protein; Glidden Co., Chicago), 13 yo arachis oil (semihardened), 5 % salts (de Loureiro, 1931) and a supplement of all vitamins except vitamin B" (Cuthbertson & Thornton, 1952). Vitamin B" activity in faeces Cups, similar to those described by Barnes et al. (1957) , were fitted to six rats. T h e collected faeces were removed from the cups daily on each of the next 3 days. The faeces from each rat were separately weighed, and the vitamin B" activity of each sample of faeces was measured microbiologically with Lactobacillus leichmannii and with Ochromonas mallramensis, as described below. Vitamin B" acticity in the walls and contents of the stomach and small intestine of rats jitted with cups and gicen a meal of the vitamin BIZ-dejicient diet or of the diet supplemented with rat faeces or with cyanocobalamin Sixteen rats were fitted with cups and starved overnight. T h e next morning six of the rats were offered weighed amounts of the vitamin B"-deficient diet, five were offered the diet mixed with bulked faeces collected overnight (1.5 parts diet + I part at https://www.cambridge.org/core/terms. https://doi.