Undernutrition And Subsequent Realimentation In Rats And Sheep

Abstract

Studies were designed to examine the comparative response of sheep and rats to undernutrition, and to examine body composition and food intake during undernutrition and subsequent realimentation. Information obtained allowed feed capacity, relative maintenance requirements and partial efficiency of feed utilization to be studied for their role in compensatory growth following undernutrition. Growth rate decreased during undernutrition in response to feed stress. An intake of feed of 52% of the ad libitum-fed controls maintained body weight, body fat, and protein percent and total body energy in the rats. Sheep responded similarly with the exception of empty body weight and energy which slightly decreased at 52% of the control feed consumption. Composition of body weight loss during starvation was similar to that of body weight gain. The alimentary tract generally decreased in weight relative to metabolic body size during starvation. Compensatory growth occurred in realimentation with both species. When previously starved rats were given an amount of feed equivalent to that consumed by continuously grown controls, difficulty was experienced in reaching equivalent body energy and protein amounts. For sheep, in some cases of feed restriction, however, efficiency of energy lay down was not a problem in realimentation on the same quantity of feed as consumed by continuously fed controls; protein synthesis was not equal, however. Weight gain during compensatory growth for both species contained more fat and less protein than did the gain of ad libitum-fed rats and sheep. The maintenance requirement for dietary energy was equal at all levels of nutrition relative to metabolic size. It was concluded, therefore, that since the maintenance requirement was not decreased during starvation, it was not responsible for subsequent compensatory growth. Increased appetite during realimentation was not found to be responsible for compensatory growth because feed capacity was equivalent for all groups. Examination of the partial efficiency of energy utilization during realimentation revealed that increased efficiency of feed utilization above the maintenance requirement was largely responsible for compensatory growth. Copyright © 1964. American Society of Animal Science . Copyright 1964 by American Society of Animal Science