The effects of protein repletion at varied levels on the growth and nutritional status of protein restricted rats

Abstract

Effects of protein restriction and subsequent repletion were studied for 34 days using 43 male weanling Sprague-Dawley rats. Thirty-three rats were fed a protein restricted diet (4% casein) for 27 days. Six of these rats were then killed. Groups of 9 rats were fed protein repletion diets consisting of 10%, 20%, or 40% casein for the next 7 days. A control group of 10 rats was fed a diet containing 20% casein for the entire study. Body weight change, food efficiency ratio, liver, kidney, and heart weights, and serum total protein concentration were assessed. Protein depletion depressed weight gain and serum protein concentration, both of which were equally improved among all refeeding groups after 1 week of repletion. Liver and kidney weights were greatest in the groups repleted with 20% and 40% casein. This study indicated that aggressive refeeding of protein provided no benefit with regard to growth or serum protein status, while causing renal and hepatic hypertrophy.