EFFECTS OF COPPER ON PERFORMANCE, FATTY ACID COMPOSITION OF DEPOT FAT AND FATTY ACYL DESATURASE ACTIVITIES IN PIGS FED A DIET WITH OR WITHOUT SUPPLEMENTAL COPPER

Abstract

Twenty crossbred barrows were equalized as to litter origin into two groups, with or without 250 ppm supplemental dietary copper. The presence of supplemental copper in the diet resulted in deteriorations in both average daily gain and feed conversion. Increases in the proportions of major long-chain unsaturated acids and concomitant decreases in the proportions of saturated acids of depot fat were associated with enhanced capacities of hepatic and adipose microsomes to desaturate stearate, oleate and palmitate among copper-supplemented pigs. The increase in the copper content of the hepatic microsomal fraction of copper-supplemented pigs was small in comparison with increases in other subcellular fractions. Several levels of copper or L-histidine were added to microsomal preparations from control or from copper-supplemented pigs. These in vitro additions did not elicit significant alterations in the rates of fatty acid desaturations to the extent that one would expect if copper functioned as an activating ion. It is inferred, therefore, that copper is involved in the desaturation reactions as a component of a cuproprotein enzyme(s).