The role of carotenoids in the biofortification of table chicken (Gallus gallus L.) eggs with ω-3 polyunsaturated fatty acids, vitamin e, and selenium

Abstract

Natural fortification of plant and animal derived foodstuffs with essential nutrients (biofortification) is regarded by modern nutritional science as an effective alternative for the synthetic food additives. Biofortified eggs are usually enriched with one or two target micronutrients via layer diets. However, the nutrition of the large part of the World’s population (both adult and infant) is characterized by the simultaneous deficiencies of different micronutrients: vitamins, carotenoids, minerals, and polyunsaturated fatty acids (PUFAs). The combined enrichment of foodstuffs with balanced set of the essential nutrients can compensate for these deficiencies and control the secondary deficiencies of the nutrients which can become deficient due to the changes in the diets of the patients. In the study presented the combined biofortification of table chicken eggs with four deficient micronutrients with different chemical and physiological properties was examined. The trial was performed in 2019 on four treatments of cage-housed Leghorn laying hens (Gallus gallus L., cross SP 789, 30 birds per treatment) during 60 days of the productive period. The concentrations of ω-6 and ω-3 PUFAs (from flaxseed oil and cake) in the diet for control treatment 1 were 2.18 and 1.97 %, respectively, ω-6/ω-3 ratio 1.11:1; the diet was also supplemented with vitamin E (150 ppm, as concentrated D-α-tocopherol) and selenium (0.5 ppm as 1:1 mixture of organic (Sel-Pleх®) and inorganic (sodium selenite) forms); the background concentration of carotenoids in this diet was 7.5 ppm. Treatments 2, 3, and 4 were fed the same diet additionally supplemented with 10; 14 and 18 ppm of carotenoids (as extract of the marigold, Tagetes erecta), respectively. The supplementation with carotenoids of diets containing the constant combination of other three target micronutrients (that we have studied in our previous trials) did not significantly affect the egg production (45.1-46.9 eggs per hen during 60 days of the trial), feed conversion ratios (1.58-1.63 kg of feed per 10 eggs and 2.43-2.50 kg of feed per 1 kg of eggs laid), and egg weight and morphology (average egg weight 65.0-65.2 g, yolk weight 18.1-18.3 g, albumen weight 39.3-39.7 g, eggshell weight 7.0-7.1 g) in layers. The eggs simultaneously fortified with the four micronutrients can be the valuable source of luthein, selenium, PUFAs, and vitamin E in human diet; these eggs could be also used as a component of multi-ingredient functional foodstuffs. The concentration of carotenoids in eggs increased with the increase in their concentration in layer diets. The increase in the concentration of the carotenoids in yolk enhanced the intensity of yolk coloration 1.66-1.84-fold, improving the market appearance and consumer attractibility of the eggs. The concentration of the four target micronutrients (per 100 g of edible part of the eggs) in the eggs from the treatment fed the highest dietary level of carotenoids were 0.7 mg for carotenoids, 62 μg for selenium, 10 mg for vitamin E, 417 mg for ω-3 PUFAs (with ω-6/ω-3 ratio 3.1:1), 3.96; 1.62; 4.37 and 2.42 times higher, respectively, in compare to “standard” (non-fortified) eggs. The daily consumption of one fortified egg will provide a consumer with 7.5 and 12 % of recommended daily consumption of ω-6 and ω-3 PUFAs, respectively, as well as 9; 39; 51 and 8 % of recommended daily consumption of vitamin A, vitamin E, selenium, and easily digestible carotenoids (primarily, lutein), respectively.