Reproduction and Lactation of Rats Receiving Pork Diets

Abstract

Female rats fed rations containing pork as the source of protein mated normally and gave birth to apparently normal young, but in some cases failed to rear them. The primary defect appeared to be in lactation. Whereas casein-fed rats usually reared an average of approximately ⅔ of the young and beef-fed rats 80–90%, pork-fed animals reared less than ⅓ of their young in certain experiments, indicating poor lactation. In other experiments the lactation was comparable to that obtained with rations containing beef. When lactation failures were encountered with pork rations, increasing the B-vitamins had no effect, but fresh liver restored the lactation to that obtained when beef or casein was fed. The levels of B-vitamins commonly used in growth experiments were found inadequate for optimum reproduction and lactation performance with casein as the source of protein, especially when the fat level was high. Attempts to obtain a defatted pork preparation which would approach the beef or casein rations in supporting lactation were not successful.