Published online by Cambridge University Press: 21 September 2007
27 Creole and 27 Plymouth Rock×Rhode Island Red hens (cross) 47 months old were used to estimate the effect of three diets; commercial diet, corn+alfalfa and homemade diet on egg weight, white, yolk, egg shell, dry matter, protein, fat and ash content of the yolk; lipid fraction and fatty acid profile of the yolk was estimated too. Eggs were collected at 53 weeks of age, 30 eggs per treatment were randomly selected for laboratory analysis. No differences (P>0.05) were found on egg, white, yolk and egg shell weight between genetic groups; inside groups there was a significant effect of diet on yolk weight in both groups. There was no effect of diet and genetic group on yolk composition (P>0.05); however there was a trend of less content of dry matter and more ash with the homemade diet in both groups. There was a group effect (P<0.05) on cholesterol, cholesterol esters and lecithin content; inside groups there was a diet effect (P<0.05) on total lipid content and triglycerides. No differences (P>0.05) between groups were found for the fatty acid profile; inside groups stearic acid was higher (P<0.05) in the yolk of hens fed with no commercial diet and linoleic acid percentage was higher (P<0.05) with corn plus alfalfa diet. Results indicated that corn+alfalfa and homemade diet seem to alter the egg components, yolk lipids and fatty acid profile.