Fertility of the white rat on purified rations.

Abstract

It has been observed that animals (rats) fed exclusively on milk 1 or on purified rations made to simulate milk 2 seldom reproduce. In those instances where reproduction has occurred, few young were born and only a small percentage have survived the suckling period. The failure in the reproduction function of these animals has been attributed to a vitamin deficiency, 3 the vitamin in question being an ether-soluble complex associated with certain fats, which is present in green leaves, egg yolk, and many natural foods. Another group of investigators working with milk 4 and so called purified mixtures in which milk has formed the basis of the ration have postulated that milk is deficient in certain essential inorganic substances. Rats fed on milk to which given amounts of iron, iodine, sodium silicate, sodium fluoride, manganese sulphate and aluminum potassium sulphate were added produced through six successive generations an average number of normal young. With combinations of two or three, or, when single salts were fed, the results were confusing, so that no conclusions could be drawn as to whether all or part of these salts were essential. When, however, these salts were added to a purified ration, in which the fat component consisted of 23 per cent lard, 5 per cent butter fat and 2 per cent cod liver oil, all animals failed to reproduce.

In order to determine whether the reproductive failure on our purified ration is due to a vitamin or inorganic deficiency we have repeated our experiments with purified rations, using (1) larger amounts of those salts which were effective in correcting the deficiencies of milk, and (2) substituting, in some cases, cotton seed oil for the lard, and in others different amounts of butter in place of an equivalent amount of lard.