INFLUENCE OF DIETARY COPPER ON THE FATTY ACID COMPOSITION OF ADIPOSE TISSUE LIPIDS AND ON THE LEVEL AND COMPOSITION OF PLASMA FREE FATTY ACIDS IN GROWING PIGS FED INDIVIDUALLY OR IN GROUPS

Abstract

The influence of dietary copper on plasma free fatty acid (FFA) levels and the fatty acid composition of adipose tissue lipids was investigated using 24 pigs, fed individually or in groups of six. Barley–fishmeal diets with and without 250 ppm supplemental copper were fed. There were no statistically significant effects on growth or carcass quality due to either dietary copper or method of feeding. There were significant increases (P < 0.001) in the copper content of the liver and kidney of the pigs fed diets containing supplemental copper. Dietary copper increased the proportion of unsaturated fatty acids (UFA) (P < 0.01) in both the total lipid extract and the triglyceride fraction of the outer layer of subcutaneous adipose tissue. Similar but less marked trends were observed in the monoglyceride, diglyceride and FFA fractions. There were significant (P < 0.001) differences between fractions with the FFA fraction having the lowest proportion of the major saturated acids (16:0, 18:0) and the highest proportion of the unsaturated acids (18:1, 18:2). Group feeding increased the proportion of saturated fatty acids. Increases in the concentration of all plasma FFA were observed in the fasting state. Relative proportions of plasma FFA were also significantly different between the fed and fasted state. Females had a significantly higher concentration of FFA than castrated males. Main treatments were without consistent effects on plasma FFA composition or concentration.