Effect of Dietary Fat and Protein on Lipid Composition and Oxidation in Chicken Muscle

Abstract

SUMMARY— Samples of white muscle ( pectoralis major ) were taken from 100 male, broiler‐type chickens which had been reared to 58 days of age on rations differing in protein level (16 or 24%) and in type of supplemental fat (5% of coconut oil, beef tallow, safflower oil or menhaden oil). Lipids were extracted from each sample and fractionated into (1) neutral lipids, (2) cephalin, and (3) lecithin. The fatty acid content of each fraction was determined by gas liquid chromatography (GLC). Lipid oxidation was measured by a 2‐thiobar‐bituric acid (TBA) method after storing each carcass for 12 days at 2°C. Values for all measurements were statistically analyzed for dietary effects and for possible correlations between composition and oxidation rates. All of the factors were significantly influenced by diet, except total lipids, cephalin, and four of the lecithin fatty acids. Correlation coefficients between TBA values and level of each lipid component were obtained after treatment effect was statistically removed. The 22‐carbon fatty acids with 4 or 5 double bonds in cephalin and lecithin, and linoleic acid in neutral lipids and lecithin were positively correlated with TBA values.