Growth of whole body and organs of growing rats during feed restriction and subsequent realimentation.

Abstract

Fifty-six Sprague-Dawley male rats (average body weight 70.6 +/- SD 11.6 g) were divided into two equal groups. One group was fed a 17% protein (N x 6.25) diet ad libitum for 42 d (Control). The second group was fed the same diet at 60% of the intake of the Control group for 14d (Restricted) and ad libitum for the remaining 28 d. Three rats per group were euthanized on d 1 and five rats per group on d 7, 14, 21, 28, and 42 and weights of the body, heart, spleen, liver, kidneys, epididymal fat, empty stomach, large and small intestines, and length of the left femur were recorded. The empty stomach, large and small intestines were dried to constant weight at 65 degrees C and assayed for crude protein content. Body weight, feed efficiency, weights of the heart, liver and epididymal fat were significantly reduced, while relative weight of the stomach and crude protein content of the small intestine were significantly increased in the restricted group during the period of feed restriction. Body and organ weights, however, compensated and caught up with control values within 14 d of feed rehabilitation and, by 28 d of realimentation, body weight, heart, liver and stomach weights were significantly greater in restricted than in control rats. Femur length was reduced by feed restriction, but continued to increase during restriction and realimentation. Gastrointestinal tract segments were less affected by feed restriction and responded more quickly to realimentation than the whole body.