Conjugated linoleic acid differentially modifies fatty acid composition in subcellular fractions of muscle and adipose tissue but not adiposity of postweaning pigs

Abstract

This study examined the interaction between conjugated linoleic acid (CLA) and dietary fat type on the enrichment of subcellular fractions, the Delta(9) desaturase index and adiposity in pigs. Early weaned piglets (n = 6/group) were fed for 35 d diets supplemented with 15 g/100 g diet beef tallow or corn oil, or 12 g/100 g tallow or corn oil plus 3 g CLA. There were no effects of dietary fat or CLA on the mass of dissected skin, bone, muscle or adipose tissue of the 7th to 9th thoracic rib sections. Medial subcutaneous adipose tissue of pigs fed tallow had smaller adipocytes than that of pigs fed corn oil. The lateral subcutaneous site was unaffected by dietary fat type. Microsomes accumulated <50% the concentration of trans-10,cis-12, cis-11,trans-13, and cis-9,trans-11 CLA as membrane and nonmembrane fractions of adipose tissue and longissimus muscle. There was no evidence of preferential incorporation of any CLA isomer into any of the subcellular fractions. Addition of CLA to the diets reduced adipose tissue nonmembrane monounsaturated fatty acids (MUFA; g/100 g total fatty acids) by 15% in corn oil-fed pigs and by 19% in tallow-fed pigs. Total saturated fatty acids (SFA) were increased by CLA commensurately in this lipid fraction. This resulted in a reduced Delta(9) desaturase index [MUFA/(SFA + MUFA)] in the nonmembrane lipid fraction of pigs fed either the corn oil or tallow diets. Thus, in spite of marked effects on fatty acid composition and the Delta(9) desaturase index, CLA had no effect on adiposity in early weaned piglets fed high fat diets.