Factors Involved in Lactation and Rearing of Young

Abstract

The work reported in this paper is a continuation of studies by Guest, Nelson, Parks, and Fulmer. 1 These investigators demonstrated that rats grow at the normal rate with various single foods as the only sources of vitamin B. However, although reproduction was approximately normal on these diets, there was a high mortality of the young. Furthermore, a large number of females died during pregnancy or parturition on these diets, the mortality varying with the nature of the seed used as a source of vitamin B. The present paper reports additional data regarding the failure of lactation on certain synthetic diets.

Oatmeal, yellow corn, white corn, and barley were each fed at a level of 60% as sole sources of vitamins B and G; likewise, wheat was fed at a 30% level as a source of these vitamins, and rice polishings, wheat germ, rice bran, and corn germ were each incorporated in the rations at levels of 10% as the only sources of vitamins B and G. The synthetic ration was composed of casein 18%, salt mixture 3.7%, butterfat 4.0%, cod liver oil 1.0%, varying amounts of the different individual foods, and dextrin to 100%. The different rations were fed to pregnant females transferred from the growing ration to the experimental diets at the time of parturition. The data from these experiments show that the mortality of the young was in practically all cases very high. Only in a few instances was the weaning weight normal; and it was also found that a high weaning weight is not necessarily accompanied by a low mortality.

Another series of experiments was performed to determine whether the foods above were deficient in vitamin B or vitamin G as far as lactation is concerned. To the diets in the first series of experiments was added 10% of autoclaved yeast as a source of vitamin G. The autoclaved yeast was prepared by moistening Fleischmann's dried yeast with distilled water—so as to form a thick paste—and autoclaving for 5 hours at 15 lb. pressure; it was then dried at 80°C. The autoclaved yeast markedly reduced the mortality of the young and enhanced the weaning weight of the young from the mothers on the various seeds and products from seeds tested.