Effects of lipid sources in the diet of laying hens on the fatty acid profiles of egg yolks.

The effects of different dietary lipids on the fatty acid profiles of eggs produced by 20- and 54-wk-old Dekalb laying hens were investigated. The 4 treatments were based on the lipid source added to the diet: soybean oil, sunflower oil, linseed oil, or control (no added oil). The experimental design was a simple random-sample design using a 4 × 2 factorial arrangement (4 treatments and 2 ages). The fatty acid composition of the yolks of eggs produced by the laying hens was analyzed. The fatty acid profiles found in the egg yolks were the same as those provided in each diet. Eggs laid by hens fed the diet containing soybean oil had a large amount of n-6 polyunsaturated fatty acids (PUFA), whereas eggs laid by hens fed the diet containing linseed oil had the highest percentage of n-3 PUFA. A decrease in PUFA deposition in egg yolks was observed as the laying hens got older. Eggs of hens fed the diet containing linseed oil presented an n-6:n-3 ratio of 2.01 in younger chickens and 2.17 in older ones. The trans fat percentages found in the egg yolks of all treatments were very low. It was concluded that the quantity of fatty acids present in the egg yolk may be altered according to the source of lipids in the diets; the addition of linseed oil to the ration of laying hens resulted in the production of n-3-enriched eggs and excellent n-6:n-3 ratios, and the egg yolks had insignificant amounts of trans fat, irrespective of the different lipid sources added to the diets or the age of the chickens.