Date of Award
Doctor of Philosophy
J. K. Bletner
O. E. Goff, J. T. Smith, K. M. Barth
A total of four experiments were conducted to determine the location of the site of absorption of xanthophylls, to determine the relationship of egg yolk color produced by various feed xanthophylls to the color of mayonnaise, and to study the effect of the level of dietary cow manure, age, ambient temperature and feed consumption of xanthophyll pigmentation of hens and egg yolks.
Increases in the level of blood xanthophylls and visual pigmentation of xanthophyll depleted hens were used to measure the absorption of xanthophylls. Surgical removal of either the duodenum, jejunum, ileum or large intestine resulted in a slight but significant decrease in absorption of xanthophyll when compared to the sham operated chicks and ligation of the ceca resulted in a slight increase. Only the removal of that section of the jejunum-ileum affected by E. maxima resulted in the chicks with no significant absorption when compared to chicks fed a diet free of xanthophylls. It is concluded that most absorption of xanthophylls in the chick takes place in this middle section of the jejunum-ileum.
Mayonnaise was made with yolks from hens fed diets containing no xanthophyll, 23 milligrams of xanthophyll per kilogram and the latter diet plus 66 milligrams of xanthophyll per kilogram from yellow, orange or red concentrate. The egg yolks appeared different, but no significant differences were found between the yolks from hens fed the diets with the added concentrates.
As measured by a triangle test, mayonnaise made from the egg yolks from hens fed the xanthophyll free diet had the lightest color. Mayonnaise made from egg yolks from hens fed the "layer" plus yellow concentrate and "layer" plus orange concentrate were not significantly different.
The red concentrate had the greatest carry-over effect. The color of mayonnaise depends on the kind and amount of xanthophylls present.
Dried cow manure was added at the rate of 0, 2.5, 5, or 10 kilograms per 100 kilograms of diets containing 0 and 23 milligrams of xanthophylls per kilogram to determine the effect on pigmentation. There was a high positive linear correlation between the amount of cow manure added and the amount of xanthophyll in the blood. There was a high negative linear correlation between pigmenting efficiency and the amount of manure added to the diet. Cow manure was a good source of xanthophylls, but its xanthophylls were not efficiently utilized.
The effect of age, temperature and amount of feed consumed on yolk pigmentation was studied. Both young and old hens were housed in rooms designed to simulate winter and summer temperatures. Half of the hens of each age group at each temperature had access to feed ad libitum and the other half received feed limited to 90 percent of that consumed in the hot rooms by hens on the ad libitum regime.
The hens in the "cool" rooms produced egg yolks with the greatest pigmentation. A four month difference in age was not a major factor in causing light colored yolks. However, egg yolk color generally became lighter as the hens grew older. In one trial limited feeding resulted in deeper pigmented yolks as measured by yolk xanthophyll levels. It is concluded that the reduction of the yolk xanthophyll levels during summer is associated more with high temperature per se, and less with aging and a drop in feed consumption as generally assumed.
Littlefield, Lloyd Henry, "The Site of Absorption of Xanthophylls and Factors Affecting Pigmentation of Chickens, Egg Yolks, and Products Made From Egg Yolks. " PhD diss., University of Tennessee, 1970.