Dietary fat and body fat: the composition of the back fats of pigs fed on a diet rich in cod-liver oil and lard

Abstract

The inner- and outer-back fats of 2 pigs fed a diet containing fat (mixture of equal parts of lard and cod-liver oil) were examined. The fats were dark brown and oxidized to a considerable degree. Crystallization of the back fats of 1 animal from acetone at -40[degree] separated each into 68% of an insoluble glyceride fraction, the I2 value of which approximated that of lard, and 32% of soluble glycerides of much higher mean unsaturation. Detn. of the component fatty acids of the acetone-separated glycerides from the inner back fat showed that the insoluble glycerides resembled normal pig fat except for the presence of somewhat more unsat-urated acids of the C16 and C20 series than are usually present in the latter. The acetone-soluble glycerides showed a striking resemblance to cod-liver oil in saturated fatty acids content, but contained less polyethenoid C20 and C22 fatty acids with correspondingly increased amts. of Ci6 and C18 unsaturated acids. It was concluded that the lard and cod-liver oil were absorbed essentially unchanged and deposited additively along with typical "synthesized" pig fat in the depots; it is suggested that depletion of antioxidant (vit. E) then occasioned oxidation of the polyethenoid fatty acids of the cod-liver oil. The results are discussed in relation to the injurious effects of diets containing unsaturated fat and little or no vit. E.