Two low protein diets differentially affect food consumption and reproductive performance in pregnant and lactating rats and long-term growth in their offspring

Abstract

We fed 2 low protein diets (LPD) to rats during pregnancy and lactation, and compared food intake and reproductive performance in the dams, and long-term growth in their offspring. The L93 and LM76 LPDs were derived from the American Society of Nutrition's recommended AIN93G and a modified version of the AIN76A purified control diets, respectively. The LPDs contained 8% crude protein in the form of casein and differed in their fat and carbohydrate sources. The purified control diets contained 19% crude protein. A regular cereal-based diet was also included, therefore, a total of 5 groups were tested. Blood urea nitrogen concentrations in dams of both LPD groups were lower than their respective controls, confirming decreased protein intake. The LM76 diet lowered food consumption of dams and produced energy malnourishment during pregnancy that persisted throughout lactation. In contrast, the L93 diet produced energy malnourishment only during lactation. Offspring of both LPD groups exhibited lower birth weights than their respective controls. Despite initiating nutritional rehabilitation at weaning (d 28), perinatal administration of both low protein diets produced long-term reductions in the body weight of male offspring. Interestingly, in the female offspring, the LM76 diet reduced birth weight for the entire duration of the study (180 d), whereas the L93 diet produced a relatively short-term (up to 58 d) reduction in body weight. This suggests that the imprinting effect of the perinatal nutritional environment on body weight is diet and gender dependent. The performance of the purified control diet groups were similar to the nonpurified diet group in most measured biochemical indices, with the notable exception of a decrease in the body-weight normalized kidney weight of the dams.