The effect of dietary copper on the fatty acid composition and physical properties of pig adipose tissues.

I . Control groups of pigs were given a basal diet alone and treated groups received the same diet supplemented with 250 ppni of copper. The animals were about 10 weeks of age at the start of the experiments and were killed when they weighed 90 kg live weight. 2. The ratio of oleic acid to stearic acid in the whole back fat (inner plus outer layers) was somewhat higher in the pigs given the copper supplement than in the control animals. The melting point of the back fat was about 1o0 lower in the pigs given the copper supplement than in the control groups. 3. Separate analyses of the inner and outer layers of the back fat showed that the ratio of oleic acid to stearic acid in the outer fat layer of the control pigs, and in both the inner and the outer fat layers of the pigs given the copper supplement, was somewhat higher than that in the inner fat layer of the control animals. The melting point of the outer fat layer of the control pigs and of both back fat layers in the pigs given the copper supplement was 10-15' lower than that of the inner fat layer of the control groups. 4. Evidence is presented that changes in the positional distribution of the fatty acids within the triglycerides of the back fats rather than differences in gross fatty acid composition are mainly responsible for the observed differences in physical properties.