The Nature of the Highly Unsaturated Fatty Acids Stored in the Lard from Pigs Fed on Menhaden Oil

In preceding reports (1, 2) it was shown that when fish oil was fed to white rats equilibrium between the diet and the depot fat resulted in from 4 to 6 weeks, and further that with a series of diets containing from 5 to 30 per cent of menhaden oil the amount of highly unsaturated acids in the depot fat was roughly proportional to their content in the diet. Relatively more of these acids, however, was found in the fat from animals on the diets of lower oil content. Analysis of the polybromides of the fatty acids from the body fats resulted in each case in higher bromine content than the bromides from the original fish oil acids, suggesting that the deposited acids were more unsaturated than those from the original oil. In the present investigation the purpose in mind was to feed a larger species of animals on a fish oil diet with the hope of being able to isolate enough of the deposited unsaturated acids to study their properties and ascertain whether they had undergone change during assimilation. Pigs were chosen as experimental animals because they will readily eat food containing large amounts of the oil, and, further, the yield of lard is sufficient for the preparation of the highly unsaturated acids.