Studies on Growth. II. Effect of Liver Extract on Food Consumption,Food Utilization and Growth.

Abstract

In certain of our experiments it has been necessary to investigate the effect of the addition of liver to the diet of growing rats. Osborne and Mendel 1 have recently called attention to the marked acceleration of the growth rate which occurs under these circumstances. It was possible from our experiments to show the difference between the action of yeast and of liver on the consumption and the utilization of food. The addition of yeast to diets partially inadequate in the vitamin B complex increases the food intake of the rats but primarily increases the degree of utilization of the food ingested. The addition of liver to an adequate diet has little effect on the degree of utilization of the food but greatly increases the food intake. The effect of yeast and of liver on the consumption of food was demonstrated in experiments in which the diets were fed ad libitum. The effect of liver and of yeast on the utilization of food was demonstrated in experiments in which the food intake was restricted so that the rats received equal quantities of food of equivalent calorific value. The results of these experiments are shown in Table I. The extraordinary effect of the liver on the rate of growth of rats may be attributed to the increased food intake resulting from stimulation of the appetite. It is noteworthy that this stimulation of appetite was most evident during the first half of the 40 day period and was hardly apparent during the last half. This investigation of the relation of the appetite to food intake, food utilization, and growth is being continued.