The effect of gestation and of protein quality on the nutritive utilization of protein



A study was made of the effect of protein quality on gestation and on digestive and metabolic utilization in Wistar rats. The protein level of the diet was 14%, and the protein sources used were: casein, beans and a mix of beans and wheat, in order to complement the essential amino-acids deficient in both protein sources.

Gestation increased food intake in the 3 groups of experiments, in which distinct protein sources were used. Protein quality did not affect food intake in the two physiological situations under study (gestation and non-gestation). In pregnant animals, the greatest weight gains were obtained with the casein diet, while in non-pregnant ones the weight increases were greater with the diet of beans and wheat. The smallest gains recorded were those of pregnant and non-pregnant rats fed a diet of beans. Gestation did not affect protein-absorption. The digestive utilization of protein was superior with the casein diet.

The study of nitrogen retention showed: 1. The pregnant animals retained more nitrogen than the non-pregnant animals with all of the diets under study. 2. In pregnant animals, the greatest metabolic utilization took place with the casein diet, with little difference between the bean and bean-wheat mix diets, although in the latter it was slightly superior.