Vitamin studies. X. Feeding technique in vitamin studies.

The work described in this paper is presented with the view of re-emphasizing the importance of the use of false screen bottomed cages in vitamin studies when rats are used as the experimental animals. Steenbock, Sell and Nelson1 have pointed out that rats which do not have access to their own feces require a larger proportion of vitamin B in the basal ration than those rats which ingest variable amounts of excretory material daily. In our studies of vitamin B in the past (using diets deficient in this vitamin), we have often been unable to account for the lack of uniformity in the development of animals from the same litters on identical diets. In fact certain animals grew satisfactorily for many weeks on a vitamin B deficient ration. In watching the animals over relatively long periods it was observed that those animals whose food intakes and growth curves were most satisfactory were in the habit of ingesting relatively large amounts of excretory material; for example we have noted a few animals which w...