Effects of genotype, age and feed on the fat components of egg yolk

Abstract: The aim of this study was to investigate if the hen’s genotype, age and diet affect fat components in egg yolk. The fat components measured were total fat content, phospholipids, cholesterol and the fatty acid profile. This trial involved 12 groups of laying hens housed in 8-hen cages enriched with perches, dust baths and nests. The genotype Lohmann Selected Leghorn (LSL) and the genotype Lohmann Brown (LB)was used. The hens were fed ad lib. with either a control diet or a diet containing 20 % hemp seed cake. Egg was collected when the hens were 32, 56 and 72 weeks old. The yolk was separated from the albumen. Total egg weight and yolk weight were registered. As expected the egg weight, yolk weight and total fat content increased with hen age. Hens of the genotype LB laid throughout the study heavier eggs than LSL-hens. The results showed that the cholesterol decreased with hen age. The hemp seed diet showed a tendency towards cholesterol lowering properties and also an effect on the fatty acid profile in the egg yolks. A significant increase of the poly unsaturated fatty acids linolenic acid and linoleic acid was seen in egg yolks from hens that had been eating the hemp seed diet. Neither genotype nor, age or diet effected the amount of phospholipids.