Depletion of oxycarotenoid pigments in chickens and the failure of aflatoxin to alter it.

Aflatoxin, a demonstrated cause of pale bird syndrome in chickens, was investigated for its effects on the depigmentation of chickens placed on a diet low in carotenoids. Chickens were pigmented by feeding for 3 wk a white corn-soy diet supplemented with 50 micrograms free lutein and 0 or 4 micrograms aflatoxin/g diet. Then birds were switched to the same diets unsupplemented with lutein. At 0, 1, 2, 3, 6, and 9 days after switching, jejunal contents and mucosa, serum, liver, and toe web of 4 groups of 10 birds were removed for analysis of their carotenoids by high performance liquid chromatography. In control birds the order of decrease in total lutein was jejunal contents greater than jejunal mucosa greater than serum greater than liver greater than toe web. Aflatoxin did not alter the depletion process, except for minor retardation of lutein depletion in the mucosa and liver. Pharmacokinetic analysis of the data indicated that lutein depletion in the integument was accomplished through three sequential reactions (lutein diester----lutein monoester----lutein----serum lutein) and that aflatoxin had no effect on the reactions. These results imply that aflatoxin induces pale bird syndrome by interfering with the accumulation of pigment by chickens rather than by enhancing the depletion of pigment.

Carotenoid composition of serum and egg yolks of hens fed diets varying in carotenoid composition.

High performance liquid chromatography of yolks of hens fed a diet based on yellow corn, alfalfa, and soybeans revealed over 20 cartenoids. Lutein, lutein monester, lutein diester, 3'-oxolutein, cryptoxanthin, zeaxanthin, beta-carotene, and zeacarotene were identified by their retention times, visible absorption spectra, behavior on saponification, and their presence or absence when lutein was the primary carotenoid fed. Three weeks after placing the hens on a white corn-soy-based diet supplemented with lutein (20 micrograms/g diet), cryptoxanthin, zeaxanthin, and zeacarotene were undetectable in the yolk and lutein, lutein monoester, lutein diester, and 3'-oxolutein assumed new equilibrium concentrations. The data imply an esterification pathway and an oxidative pathway in laying hens for the metabolism of hydroxycarotenoids. Consideration of the concentrations and ratios of lutein and its metabolites in serum and yolk suggest a nonovarian site for the metabolism of lutein in laying hens.

Aflatoxin-impaired ability to accumulate oxycarotenoid pigments during restoration in young chickens.

The mechanism by which aflatoxin causes paling in chickens was investigated by measuring its effect on the restoration of pigments in 3-wk-old birds made pale by feeding a white corn-soy diet. Pigment restoration was accomplished by feeding the same diet supplemented with lutein (70 micrograms/g of diet), which is the major oxycarotenoid pigment in chicken diets and tissues. The oxycarotenoids (free, monoester, and diester forms of lutein) in the toe web, liver, serum, and jejunal mucosa of control and aflatoxin-fed (2 micrograms/g of diet) birds were measured by HPLC at 0, 1, 2, 3, 6, and 9 days of repletion. Aflatoxin caused a significant (P less than .05) depression of all forms of lutein in the toe web. In the liver, aflatoxin decreased lutein significantly (P less than .05) but increased lutein monoester and lutein diester. Lutein accumulation in serum and mucosa were inhibited significantly (P less than .05) starting on Days 2 and 3, respectively. These data imply that the normal accumulation of lutein from the diet proceeded into and through the mucosa to the serum to depot sites in the liver and integument, where lutein was acylated to its monoester, which was acylated to its diester. Further, aflatoxin inhibited, apparently independently, the accumulation of lutein by the mucosa, serum, liver, and integument. Pharmacokinetic analysis of the data indicated that both acylation steps in the integument were sensitive to aflatoxin, but the passage of lutein from serum into the integument was not affected.

Alterations in carotenoid metabolism during ochratoxicosis in young broiler chickens.

The mechanism by which ochratoxin impairs the ability of chickens to utilize dietary carotenoids for carcass pigmentation was investigated. Graded doses of pure ochratoxin A (0, .5, 1.0, 2.0, and 4.0 micrograms of toxin/g of feed) were incorporated into a white corn-soy diet supplemented with an efficiently used oxycarotenoid (110 micrograms free lutein/g) and fed to broiler chicks from day of hatch to 3 weeks of age. Concentrations of free lutein and its metabolites, lutein diester, lutein monoester, and oxolutein, in the jejunal contents, jejunal mucosa, serum, liver, and toe web from these birds were measured by high performance liquid chromatography. Based on the threshold level of ochratoxin required for an effect on the concentrations of carotenoids and on the severity of the effect, five separate loci for the action of ochratoxin on carotenoid metabolism were detected: dilution of carotenoids in intestinal contents, depressed uptake by intestinal mucosa, depressed transport in serum, altered accumulation in liver, and altered acylation steps in the integument.

Absorption, transport, and deposition in chickens of lutein diester, a carotenoid extracted from marigold (Tagetes erecta) petals.

Young broiler chickens were fed from hatching until 3 weeks of age with a white corn-soy diet amended with varying amounts of lutein diester to supply 0, 5, 10, 20, 40, and 80 micrograms free lutein/g diet. The lutein diester was added as a stabilized, microencapsulated extract of marigold (Tagetes erecta) petals. The concentrations of lutein diester, lutein monoester, and lutein in the contents of the jejunum and large intestine and in serum, liver, and toe web from these birds were measured by high pressure liquid chromatography. The contents of the jejunum and large intestine contained a mixture of lutein diester, lutein monoester, and lutein. The serum contained lutein (approximately 90%), lutein monoester (approximately 10%), and traces of lutein diester. The liver contained the three carotenoid classes in ratios reflecting the serum ratios. The ratios in toe web, an integumentary depot site, were reversed with lutein diester much greater than lutein monoester greater than lutein. The concentrations of each class in each tissue bore a linear relationship to the concentration of lutein diester in the diet. A simple explanation for these data is that the dietary lutein diester was hydrolyzed mainly to lutein, which was absorbed through the intestinal wall into the blood stream where it was transported to the liver, a storage site, and to the integumentary sites where it is esterified to lutein diester which is the main depot form.

Lutein as a model dihydroxycarotenoid for the study of pigmentation in chickens.

A model for the study of pigmentation in young chickens is described in which a white corn-soy based diet supplemented with varying amounts of free lutein (0, 5, 10, 20, 40, and 80 micrograms/g diet) was fed from hatching until 3 weeks of age. The carotenoid content of tissues dissected from chicks of the various groups was measured by high pressure liquid chromatography. In intestinal contents, three forms of lutein were found, with lutein monoester greater than free lutein greater than lutein diester. In the serum, free lutein (96%) and lutein monoester (4%) were found. In the liver, free lutein (80%), monoester (20%), and traces of diester were found. In the integument (toe web), diester greater than monoester approximately equal to free alcohol were found. In each tissue, the concentrations were directly proportional to the dietary concentration of free lutein. The simplest explanation of the data appears to be that part of the free lutein in the diet is esterified during its passage down the intestinal tract and, regardless of its status when absorbed, it is transported in the body as the free alcohol. When it enters depot sites such as the integument, lutein is deposited mainly as esters, presumably as the result of local enzymatic activity.