Krill Meal Enhances Antioxidant Levels and n-3 Fatty Acid Content of Egg Yolk from Laying Hens Fed a Low-Pigment Diet

Effect of Dietary Carotenoid on Egg Yolk Color and Singlet Oxygen Quenching Activity of Laying Hens

The effects of dietary carotenoids on egg yolk were investigated in this study. Forty Rhode Island Red (RR) and 40 Silky Fowl (SF) hens that were 60 weeks old were used. Hens of each breed were randomly divided into four dietary groups. One group was fed a basal diet (crude protein 17%, metabolizable energy 2800 kcal/kg) only, whereas the other groups received a specific additive, namely, paprika extract, marigold petal extract, or Paracoccus cell powder, in addition to the same basal diet. The color and carotenoid content of egg yolk and singlet oxygen quenching activity were measured after 4 weeks. The total carotenoid content, zeaxanthin content, and singlet oxygen quenching activity in the yolk differed significantly between breeds and between diets (two-way ANOVA). The lutein content in egg yolk was affected by breed and diet, as well as by the interaction between these two factors. Regarding the Roche Yolk Color Fan values, only the effect of diet was significant. In terms of objective egg yolk color, there was a significant difference in lightness and yellowness between breeds. The total carotenoid content was higher in SF than in RR in all the groups. Likewise, the levels of zeaxanthin and lutein in the yolk were higher in SF than in RR (P<0.05). The results of the present study suggest that dietary carotenoids are effective feed additives for laying hens, especially SF, to improve the color and singlet oxygen quenching activity of egg yolk.

The effect of astaxanthin and lycopene on the content of fatty acids in chicken egg yolks

Carotenoids that do not have provitamin activity – lycopene and astaxanthin can accumulate in the yolks of chicken eggs and give them colour, as well as affect the metabolism of lipids and fatty acids, which determine the biological value and functional capacity of such products. The aim of this study was to determine the fatty acid composition of egg yolk lipids by adding oily extracts of lycopene (20, 40 and 60 mg/kg feed) or astaxanthin (10, 20 and 30 mg/kg feed) to the diet of laying hens. 45 High Line W36 chickens at the age of 24 weeks were used for the experiment. It was found that the addition of lycopene at doses of 20, 40 and 60 mg/kg and astaxanthin at doses of 10, 20 and 30 mg/kg of feed for 30 days did not significantly affect the ratio of saturated and most monounsaturated fatty acids in egg yolks and Σ SFA and Σ MUFA. Lycopene at a dose of 20 mg/kg of feed reduced the content of cis-11-eicosenoic acid, and astaxanthin at a dose of 10 mg/kg of feed reduced the content of palmitoleic acid by increasing the proportion of cis-10-heptadecenoic acid in the lipids of egg yolks. Addition of lycopene to the feed of laying hens at a dose of 20 mg/kg of feed caused a decrease in the particles of linoleic, which belongs to ω6 PUFA, and cis-eicosenoic acids. Astaxanthin enrichment of the diet of laying hens at a dose of 30 mg/kg reduced the proportion of cis-4,7,10,13,16,19-docosahexaenoic acid, which belongs to ω3 PUFA, in the lipids of the yolks. Σ PUFA decreased in the lipid fraction of yolks only under the influence of lycopene supplements at a dose of 20 mg/kg of feed. Feeding of laying hens with lycopene and astaxanthin supplements did not affect Σ ω3 PUFA and Σ ω6 PUFA. Lycopene at a dose of 20 mg/kg decreased, and astaxanthin at a dose of 30 mg/kg of feed increased ω3/ω6 PUFA in lipids of egg yolks. The results of the research can be used to select oils in combination with carotenoids of natural origin in the diet of chickens during the creation of a model of enrichment of egg yolks by individual representatives of ω3 PUFA and ω6 PUFA.