The objective of this study was to determine the effects of feeding high levels of corn distiller's dried grains with solubles (DDGS) on egg production, internal quality of eggs, chemical composition and important nutrients content of egg yolk. Four diets were formulated to contain 0, 17, 35 or 50% corn DDGS in a corn and soybean meal base. A total of 240 54 -week-old single-comb White Leghorn laying hens were randomly allotted with 2 birds per cage with three consecutive cages representing an experimental unit (EU). Each EU was assigned to one of the four dietary treatments according to a completely randomized design. Hens were fed for a 24-week experimental period after transition feeding to gradually increase corn DDGS inclusion over a four-week period. After the first 12-wk period, the diets were reformulated to meet amino acid requirements.

Egg production was recorded daily and feed consumption was measured weekly. Egg component, yolk color, Haugh unit during storage, and shell breaking strength were measured every two weeks. Chemical composition and nutritional components in egg yolk were measured every two weeks. Chemical composition of egg yolk including protein, lipids, and moisture was determined. The nutritional components in egg yolk, including fatty acid composition, and the content of cholesterol, lutein, and choline were measured.

Egg production, egg weight, egg mass, feed intake, and feed efficiency were adversely affected by the highest level of DDGS (50%) in the diet before diet reformulation. Once diets were reformulated with increased concentrations of lysine and methionine, differences among the dietary treatments were reduced and the performance of the 50% DDGS diets was improved significantly, and no differences in egg production, egg weight and feed intake among DDGS treatments were found during the last 6 weeks of study. DDGS diets positively affected the internal quality of eggs during storage. Yolk color increased linearly as DDGS concentration increased, and Haugh unit was improved from 50% DDGS diet treatment group. Shell breaking strength was not influenced by DDGS diets. Shell weight percentage increased at 50% dietary DDGS level. Egg yolk from hens fed highest DDGS-containing diet tended to have higher fat content and lower protein content. Total polyunsaturated fatty acids were significantly increased by DDGS diet. The contents of choline and cholesterol were initially higher in 50% DDGS treatment group, but the difference among four DDGS treatments reduced in the later period, especially no difference was found during the last 4 weeks. Lutein content increased linearly as DDGS levels increased.

It was concluded that up to 50% of DDGS could be included in the layer's diet without affecting egg weight, feed intake, egg production, and egg internal quality as long as digestible amino acids were sufficient in DDGS-added diets. Moreover, this study indicated that feeding high levels of DDGS can increase the content of lutein and polyunsaturated fatty acids in egg yolk, but may not influence the content of cholesterol and choline.