A Study of the Effects of Certain Diets Upon the Growth and from of Albino Rats

Abstract

A study has been made of the effects of certain diets on the form and development of albino rats. Compared with normal animals of the same age, measurements show that in the case of animals receiving a deficient supply of vitamin A there resulted a lesser retardation of increase in the length of body and of leg, the chest girth, and the width of hips than in the body weight. In proportion to their body length, those animals which received a small amount of vitamin A food, and made gains in weight of 22–30 grams in 8 weeks, show about the same chest girth as normal animals. The leg bones of animals on the vitamin A-deficient diets were found to be relatively longer in proportion to their body length than the normal. With the exception of the humerus, the long leg bones showed no marked difference from the normal in size or shape. The humerus showed a tendency to be thicker in relation to its length, than was found in the case of the bone of normal animals of the same age, but there was practically no difference when comparisons were made between animals of the same weight. The body form of albino rats stunted by a deficiency of vitamin B is also different from the body form of normal animals of the same age. Compared with normal animals of the same age, the animals retarded in growth because of a deficiency of this vitamin show, as in the case of the vitamin A-deficient animals, that there was a lesser retardation of increase in the length of body and legs, chest girth and width of hips than in body weight. In proportion to the length of the body, these animals have smaller chests and show a tendency to have longer leg bones relative to their body length, than do normal animals of the same age. The humeri, especially, are relatively long and slender compared with the normal. A study was also made of the development of animals from a stock which for generations had received diet 16, a diet somewhat poorer than the normal, but one that earlier work has shown to be adequate for growth and reproduction through many generations. In the case of the mature animals, and here the larger numbers used in the comparison make the values of more significance, there appears to be no consistent difference in body trunk form of the animals on diets 16 and the better diet, diet 13. The younger animals on diet 16 generally show longer leg bones relative to body weight than was found in the case of diet 13 animals of the same age, but the differences were negligible for animals of the same weight. The tibias, femurs, and humeri of the very old animals on 16 show a tendency to be slightly thicker or greater in diameter relative to their length than is the case with the very old rats on diet 13. The small differences that have been found in the bone and body structure of rats on diets 13 and 16 stand in contrast to the larger differences that have previously been found in the life span, reproductivity and resistance to lung infection of the animals on these two diets.