Influence of lycopene and astaxanthin in feed on metabolic parameters of laying hens, yolk color of eggs and their content of carotenoids and vitamin A when stored under refrigerated conditions.

Orientating investigations were carried out in order to test the influence of oil extracts of lycopene (20, 40 and 60 mg/kg feed) and astaxanthin (10, 20 and 30 mg/kg feed) as feed additives on the metabolic parameters (glucose, creatinine, cholesterol) and enzyme activities (alanine aminotransferase, ALT; aspartate transaminase, AST) of laying hens. Eggs from these hens were stored at refrigerator temperatures of 4°C and 12°C for up to 30 days and analyzed for vitamin A, carotenoid and yolk color. 45 laying hens (Hy-Line W36 cross, 23 weeks of age) were divided in three groups of 15 birds each (control, lycopene fed group, astaxanthin fed group). Blood samples were taken from the hens and laid eggs were collected on days 31, 61, and 91 of the study. The eggs were stored for 30 days in refrigerators. Both lycopene and astaxanthin increased the content of glucose in serum (Р⟨0.05). The content of creatinine and cholesterol, and the activity of ALT, AST and alkaline phosphatase varied dose-dependently. With the exception of cholesterol, metabolite concentrations in the serum of laying hens fed different lycopene and astaxanthin doses did not exceed clinically accepted physiological levels. The carotenoid content and color of the egg yolks from laying hens fed astaxanthin was significantly higher (Р⟨0.05) compared to lycopene fed birds. Refrigerator storage of the eggs did not affect carotenoid content and egg yolk color compared to freshly laid eggs. Both feed additives showed a favorable effect on the metabolism of laying hens and the enrichment of egg yolks with carotenoids, astaxanthin significantly more (Р⟨0.05) than lycopene.