Yolk cholesterol in eggs from various avian species.

Studies were conducted to establish the differences in yolk cholesterol concentrations in eggs from various avian species. Cholesterol was determined by a modification of the colorimetric procedure of Pearson et al. (1953). Species listed in increasing concentrations of cholesterol per gram of yolk, were guinea fowl, chicken, pheasant, quail, turkey, duck, goose, and dove with an overall range of 12.77 to 21.99 mg of cholesterol per gram of yolk. Significant differences in cholesterol concentrations also were found between domestic and wild genetic groups for turkeys and ducks. In a second study, eggs from 7 inbred lines of chickens showed significant differences in yolk cholesterol. The same general result was found in an analysis of eggs from 17 commercial test strains of chickens at two different ages. Yolk cholesterol tended to decrease as age of hen increased. These results confirm the possibility of genetically selecting for decreased yolk cholesterol if economic or other conditions warrant. The increased efforts required to decrease yolk cholesterol by this approach would undoubtedly be expensive.

A nutrient re-evaluation of shell eggs.

Most data on the nutrient composition of shell eggs were obtained before 1950. Since then, management systems for egg production and analytical methods for many components have changed. Freeze-dried whole egg, yolk and white samples were prepared from eggs obtained from a single source of 15 month old White Leghorns. The sample were packaged under nitrogen and held at -20 degrees C. until analyzed. Conversion factors are included for expressing the amount of each component on a per egg as well as a per 100 g. edible liquid basis. This re-evaluation of nutrient data included total solids, lipid, protein, cholesterol, ash, calories, amino acids, fatty acids, vitamins and minerals.