| Brown eggs have a significant share of the world market. They are preferred in countries such as China, France, Spain, Korea, Australia, and the United Kingdom; and their market share is on the rise. Although shell color is independent of the egg's composition, consumers in many parts of the world are willing to pay more for brown eggs. Shell color is affected by factors such as genetics, disease or other sources of stress, and hens' age. Vanadium may be introduced into poultry diets in poor quality phosphate supplements. The objectives of this study were to quantify the changes in eggshell color with hens' age and dietary vanadium using machine vision; and to measure the albumen quality and foaming properties of eggs from hens fed diets containing different concentrations of supplemental vanadium.; Eggs from commercial egg-type layers were collected on three consecutive days, every month, for 9 months. A machine vision system coupled with color analysis software was used to obtain the L*a*b* values of each eggshell. Lightness (L*) increased and redness (a*) decreased with time; the changes in yellowness (b*) were not substantial. The L*a*b* values adjusted for the increase in egg size with hens' age were found to be practically constant in time, providing quantitative support for the hypothesis that eggs from older hens are paler.; Dietary supplemental vanadium (15--100 ppm) also increased L* and decreased a*, with no change in b*. Foam stability and Haugh units decreased significantly due to vanadium (30--100 ppm). Eggshell color and foam stability, but not Haugh units, benefited from Vitamin C supplemented at 100 ppm to the vanadium (15--30 ppm) diets after vanadium toxicosis had developed. Vitamin E (100 IU) or beta-carotene (100 ppm) did not alleviate any of the already established effects of vanadium (15--30 ppm). 500 IU Vitamin E or 500 ppm beta-carotene or a mixture of 100 ppm Vitamin C, 100 ppm beta-carotene and 100 IU Vitamin E added to diets simultaneously with 15 ppm vanadium prevented any change in eggshell color.; The alleviating effects of any supplement are important for those conditions under which it would be economical to use phosphate sources containing high levels of vanadium. |
