Metabolism and Growth Rate of Rats

Abstract

This paper presents day-to-day oxygen-consumption data on rats, from birth to 4 months, and brings out the following salient features: The metabolic rate rises from about 550 Calories per square meter per day in early infancy (the low values perhaps being due to low muscle tonus and low endocrine activity) to 1100 basal or 1200 non-basal at the age of 45 days or at a body weight of 100 gm.; thereafter it declines to 800 basal and 850 nonbasal, the decline in metabolic rate tending to parallel the decline in percentage growth rate. The decline in metabolic rate (as in growth rate) with increasing body weight is more rapid in the females than in the males. When total metabolism is plotted against body weight on logarithmic paper, the resulting distribution exhibits “breaks” which apparently are associated, in part, with changes in percentage growth rate.