EFFECTS OF ENVIRONMENTAL TEMPERATURE AND DIETARY COPPER ON GROWTH AND LIPID METABOLISM IN PIGS. II. FATTY ACID COMPOSITION OF ADIPOSE TISSUE LIPIDS

Abstract

Pigs were fed diets with and without 250 ppm supplemental copper and kept outside during winter with unheated colony houses for shelter, or in a heated barn. Lipids were extracted from the outer backfat and pure triglycerides were prepared by thin-layer chromatography. Fatty acid analysis indicated only minor changes in fatty acid composition of the triglycerides due to either dietary copper or environmental temperature. Fatty acid analysis of the total lipid extract, however, indicated that there were differences between the two methods of evaluation. The lipid extract analysis gave a more unsaturated fatty acid pattern than that of the pure triglycerides. Although the fatty acid composition was not altered significantly by type of rearing (outside vs. inside), there was an increased proportion (P < 0.05) of unsaturated fatty acids (UFA) due to dietary copper when the fatty acid composition was determined on the lipid extract. This suggests that lipid fractions other than triglycerides were enriched in UFA and that the effect of dietary copper on the fatty acid composition of adipose tissue lipid is due to changes in the composition of other lipid fractions, possibly free fatty acids. This may be related to a disturbance in the balance between lipolysis and reesterification of fatty acids.