Effect of protein quality on weight and composition of the carcass in pregnant and non pregnant rats.

The effect of diets with different protein qualities on net weight and on the composition of the carcass (the animal being skinned and gutted) were studied in pregnant and non-pregnant rats of the Wistar breed. The animals were fed with diets containing the following protein sources: casein + 5% DL-methionine, beans and a mix of beans and wheat, all with a protein level of 14%. Percentage weight gains in the carcass were in all cases greater in non-gestating animals than in gestating animals. The water content of the body was similar in all the groups tested. The quality of protein did not affect nitrogen content; however, a smaller proportion of nitrogen was observed in gestating animals than in non-gestating animals. With respect to fat content of the carcass, a greater quantity of fat was observed in the bodies of gestating rats than in non-gestating rats, which was only significant in the case of the bean-wheat mix diet. Within each group of gestating and non-gestating rats, there was a greater quantity of fat in those animals fed with casein.