The Occurrence of 5 B-Vitamins in the Tissues of Pregnant Rats Fed Rations Satisfactory and Unsatisfactory for Reproduction

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Abstract
In an effort to determine the cause of unsatisfactory reproduction in rats fed a ration containing pork muscle and yeast as the main sources of protein and the B-vitamins, the concentrations of thiamine, riboflavin, niacin, biotin and pantothenic acid have been measured in the diets and in the tissues of pregnant animals. The occurrence of the 5 vitamins in hepatic, carcass, and fetal tissues on the final day of 1st and 2nd pregnancies has been determined in animals fed two types of rations. A modified Steenbock stock ration was used as the control diet, since it was known to promote normal reproduction. Vitamin assays of the rations revealed that the animals which showed poor reproductive performance were consuming quantities of thiamine equal to those fed the modified stock diet, but that their riboflavin intake was somewhat lower than that of animals fed the control ration. The greatest differences in vitamin intakes were observed in respect to biotin and pantothenic acid; the inadequate diet provided only 15% as much of these factors as was supplied by the stock diet. The concentration of vitamins in the tissues indicated that a desirable intake of riboflavin during reproduction falls in the range of 36 to 90 µg per day. Animals fed either ration contained large amounts of niacin in their tissues, and the concentration of this factor seemed independent of the dietary intake. The concentration of biotin in both the maternal liver and the young of animals fed the ration providing minimal supplies of biotin was subnormal. Animals receiving the inadequate ration were markedly depleted in pantothenic acid as judged by the low concentration of this factor in the hepatic tissue. They appeared to transfer large amounts of this vitamin to the developing young until severe maternal depletion occurred. When dietary inadequacies of both biotin and pantothenic acid occurred, as seemed to be the case when the Pork I ration was given, the animals lost the ability to store thiamine in customary amounts in their livers, after dietary supplies had been transferred to the fetuses. Perhaps in a simultaneous of thiamine is needed to permit deposition of normal quantities in the liver.