Abstract
It was reported 1 that second generation albino rats on 2 diets, A and B, containing 15 and 20% liver protein respectively, were unable to nurse their young. The failure of lactation was not caused by a deficiency of vitamins since the administration of increased amounts of yeast and cod liver oil as well as the daily administration of 0.3 cc. of wheat germ oil led to no improvement. The daily administration of 0.5 to 1.0 gm. of dried whole liver (dried in a vacuum at 100°C.) also had no beneficial effect on lactation, where-as 1.5 gm. of raw liver daily enabled the animals (9) to nurse their young successfully, 26 animals (45% of the 57 born) being weaned at 21 days of age. The success of raw liver in imparting the ability to lactate is further demonstrated in that third generation animals (2 males and 4 females on each diet) were considerably heavier than the parent generation had been at the same age, the males remained fertile longer than the second generation males, the females had normal oestrus cycles and they were able to nurse their young successfully without additional supplement to the diet.
Fifteen first generation animals reared on the diets supplemented by 0.5 gm. of dried whole liver in addition to yeast and cod liver oil grew at a faster rate than 32 control animals. Lactation was also improved by the dried liver supplement in that the percentage of the young which were weaned was approximately twice that of control animals (45% as against 26%) and the young were considerably heavier when weaned. The influence of the whole liver does not reside in the added protein or fat since growth and lactation were not appreciably influenced by supplementing the diets of a like number of animals with fat-free liver or liver fat equivalent in amount to the dried whole liver supplement.
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