Quality and oxidative stability of eggs laid by hens fed marigold extract supplemented diet

Abstract

The research objective was to determine the influence of marigold extract and storage duration on the indicators of egg quality and on the oxidative stability of eggs. The 5-wk long research was carried out on 300 laying hens. Laying hens were divided into control group (C-without marigold extract supplementation) and 2 experimental groups (E1-supplemented 1 g/kg of marigold extract and E2-supplemented 2 g/kg of marigold extract to diet). The eggs were analyzed on 2 occasions, as fresh eggs (1 D after collecting in the facility) and after 28 D of storage in a refrigerator on +4°C. On both occasions, there were 30 eggs analyzed per each group. Statistical analysis of the research results proved influence of marigold extract supplementation and storage duration on the weight of eggs (P < 0.05) and on the eggshell thickness (P < 0.001), but they did not have any influence on other indicators of external egg quality. Storage duration affected (P < 0.001) all indicators of internal egg quality, whereas supplementation of marigold extract influenced (P < 0.001) only the pH value of yolk. Supplementation of marigold extract influenced (P < 0.001) the yolk color intensity. There was a significant increase in the value of yolk color, starting with 9.63 in the C group and raising to 12.77 (E1) and 13.50 (E2) in fresh eggs. Yolk color of stored eggs was more intensive than the yolk color of fresh eggs in all 3 groups (P < 0.001). Supplemented marigold extract did not influence the obtained results of lipid oxidation in yolks, whereas storage duration had influence (P < 0.05) on oxidation intensity. The most favorable value of oxidation in fresh eggs was determined in the E2 group (0.545 μg MDA/g), and in stored eggs in the E1 group (0.615 μg MDA/g). Based on the research results, it was concluded that the supplementation of marigold extract had favorable influence on the yolk color intensity and on the oxidative stability of eggs without having negative influence on other egg quality indicators.

Keywords: egg quality; lipid oxidation; marigold extract; storage duration; yolk color.