Effect of repeated reproductive cycles on maternal nutritional status, lactational performance and litter growth in ad libitum-fed and chronically food-restricted rats

Abstract

To evaluate the combined effects of repeated, closely spaced reproductive cycles and dietary intake on maternal nutritional status, lactational performance and litter growth, rats were fed ad libitum or 75 or 60% of ad libitum intake. Dietary treatment began 28 d before breeding and continued until d 14 of the first (L1) or second (L2) lactation. Body weight and carcass fat concentration of dams and their litters were affected in the 75% group; milk yield, milk protein and lactose concentrations and energy content were affected only in the 60% group. Dams and their litters were heavier, had more total carcass protein and higher plasma albumin values in L2 than L1. There was no effect of reproductive period on milk yield or composition. These results indicate that repeated reproductive cycles did not compromise maternal nutritional status, lactational performance or litter growth. Improved outcomes in L2 among the restricted rats appeared to result from gains during the interval between reproductive periods and early in the second pregnancy.