The composition of the depot fats of a pig fed on a diet rich in whale oil

Abstract

The component acids present in the perinephric, inner back and outer back fats of a pig which had been fed heavily on whale oil were examined. Considerable proportions of the characteristic whale oil fatty acids passed into the fat depots, especially in the case of the outer back fat. Crystallization of the perinephric fat from acetone at -40[degree] separated it into 26% of a soluble fraction, which approximated whale oil in composition, and left 74% of insoluble material, the composition of which closely resembled a normal pig perinephric fat except for the presence of somewhat more unsaturated acids of the C16 and C20 series than are usually found in the latter. The depot fats from the animal the diet of which had included 50% of whale oil therefore consist of a mixture of whale oil with the typical fat synthesized by the pig from non-fatty food. The compositions of the individual component acids in each of the 3 fats, when calculated on the assumption that they were mixtures of typical"synthesized" depot fats with whale oil in appropriate proportions, agreed closely in most cases with those determined experimentally. It was noticeable that the high degree of unsaturation of the acids of the C20 and C22 series in whale oil was reproduced in the corresponding fatty acids of the deposited fat. This emphasizes the manner in which the whale oil glycerides had been assimilated and deposited in the depots without any chemical alteration. The greater unsaturation (leading to softer consistency) of the fat in the outer layers of the back adipose tissue was attained by a relatively higher proportion of deposited whale oil to typical synthesized pig fat than in the inner layers of perinephric fat.