Dietary Requirements for Fertility and Lactation. XVI. Potency of "Vitavose"versus Dehydrated Yeast in Vitamin B.

Abstract

Yeast and wheat embryo are the 2 most potent sources of vitamin B. I have demonstrated that, while a cold 75% ethyl alcoholic extract of 6.5 gm. whole wheat embryo per animal per day furnishes enough vitamin B for excellent growth, it is necessary to supply the same alcoholic extract of at least 22.4 gm. per lactating rat daily to furnish enough vitamin B for normal lactation. Recently I have perfected a quantitative biological method for the study of vitamin B requirements for lactation. The technique consists of administering to lactating mothers (Mus norvegicus albinus) rearing litters of 6 young at the first plateau curve of the nurslings (showing depletion of vitamin B reserves of the mothers) quantitatively graduated amounts of dehydrated yeast, or concentrated extracts therefrom, separately from the ration. By such technique it became apparent that is was necessary to furnish 1500 mg. of Harris yeast daily to the lactating mothers to enable them successfully to wean their litters. This amount of yeast dosage, we have determined, is approximately 3 times that required for optimum growth of the adult and non-lactating rat. We have had occasion to examine by our rather delicate biological method the potency of a dehydrated baker's yeast. Twenty-three lactating mothers with litters of 138 young were employed to assay that brand of dehydrated yeast. Sixteen mothers successfully weaned 88 out of 96 young on a daily dosage of 1500 mg., or a lactation efficiency index of 91.6%; and 7 mothers weaned 41 out of 42 young on a daily dosage of only 1200 mg., or a lactation efficiency index of 97.6%. Our method discloses that, in so far as lactation requirement is concerned, the Harris yeast, claimed to be a concentrated extract from brewer's yeast, has no greater biological value than the “Federal” brand of dehydrated baker's yeast.