Effect of Dietary Animal Tallow and Vegetable Oil on Fatty Acid Composition of Egg Yolk, Adipose Tissue and Liver of Laying Hens

Abstract

Effect of four levels of dietary animal tallow, soybean oil, sunflower oil and rapeseed oil on the changes in the fatty acid composition of liver, egg yolk and adipose tissue of laying hens was studied. Changes in the fatty acid composition were generally proportional to the respective fatty acid patterns of dietary fat. Linoleic acid from soybean, sunflower oil and rapeseed oil source was preferentially deposited in tissue and egg yolk with a simultaneous depression of oleic and palmitoleic deposition. Constant or increasing level of long chain saturated acid was found irrespective of dietary stearic acid level when hens were fed high linoleic acid diets.Animal tallow or low-fat decreased linoleic acid and increased oleic acid in tissue and egg yolk, indicating that linoleic acid was conserved in the body fat of laying hens and that oleic acid was preferentially synthesized from non-fat or fat precursors. High dietary levels of rapeseed oil suppressed the linoleic acid deposition and increased the oleic acid in the liver. Erucic acid of the diet was deposited in substantial amount in egg yolk and liver, whereas none was detected in adipose tissue.Linolenic acid from soybean oil was more actively deposited in egg yolk and tissue than from rapeseed oil. The metabolic fate of individual fatty acids from different fat sources and their interaction due to the fatty acid make-up of dietary oils were discussed.