FURTHER OBSERVATIONS OF RAPID GROWTH OF THE ALBINO RAT

Abstract

Albino rats (21 [male][male]) of the Osborne and Mendel strain and grown under identical environmental conditions as were Osborne and Mendel''s rapid growing rats were selected. The individual body weights at weaning age (21 days) of most of the animals were 40-55 gm. Food and water were given ad libitum. The rations fed included cereal and cereal products, dried milks, linseed oil meal, soluble blood meal, mineral salts, and a liberal content of cod liver oil. In addition dried yeast and lettuce were fed in abundance. On this diet the average daily gains of body weight between 60 gm. and 300 gm., 60 gm. and 400 gm., and 60 gm. and 500 gm. were 6.0 gm., 5.2 gm., and 4.5 gm. respectively. Some individuals showed an average daily gain of approximately 7 gm. in growth between 60 gm. and 300 gm. body weight. This is the most rapid growth of albino rats yet recorded, as far as the authors are aware.