Studies of Reproduction in Rats Using Large Doses of Vitamin B12 and Highly Purified Soybean Proteins

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Abstract
Two studies are described concerning reproduction in rats with the use of purified diets. One is the effect of large doses of vitamin B12 on the survival of young, and the other is the effect of different protein concentrates, including highly purified soybean protein, on reproduction. When vitamin B12 was added, the number of young weaned ranged from 90 to 100% regardless of whether the amount added was 10, 25, 500 or 1000 μg per kilo of diet. There was no evidence that large doses of vitamin B12 in the diet of the mother were toxic to the offspring. Without vitamin B12, the average weaning weight and the percentage of litters and of young weaned were less than with vitamin B12. Two commercial soybean proteins were exhaustively extracted with boiling water and with boiling 70% isopropyl alcohol. Five generations of females which received a synthetic diet that contained these purified proteins weaned 90% or more of their young. These data show that the diet was not deficient in an unidentified factor or factors required for reproduction and lactation in rats, and it is concluded that if unidentified factors are required for reproduction in rats, they are held very tenaciously to the protein concentrates.