The Relation Between Vitamin B12 Deficiency and Lactation in Rats Fed Purified Casein Rations

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Abstract
The feeding of vitamin B12-deficient casein-containing rations to mother rats during the lactation period resulted in smaller pre-weaning weights and post-weaning weight gains of the young, and in a decreased storage of B12 in the organs of the young previous to the time that they began to eat solid food. Significantly lower pre-weaning weights of the young occurred more quickly when the B12-deficient rations contained yeast than when they were yeast-free. A similar effect was noted when lactose-containing rations were compared to lactose-free rations. Retaining mothers over several generations on yeast-containing B12-deficient rations, supplemented and unsupplemented with B12, did not result in differences between pre-weaning weights of young or between post-weaning weight gains of young that were markedly greater than those that occurred in the parent generation. Access to the B12-fed mother's excreta was not found to be a significant factor in explaining differences in weights or weight gains between the young from B12-deficient and those from B12-supplemented mothers. It appeared that a decrease in the quantity of milk produced by B12-deficient mothers was the primary factor in explaining the lower weight gains prior to the time the young began to consume solid food. The decreased milk output was accompanied by decreased food consumption by the deficient mothers.