The role of carotenoids in breeding poultry

Carotenoids are essential ingredients in animal feed. They are not only important as pigments but serve as health promoting antioxidants and as a precursor of vitamin A. Because of their importance in visual perception of animal products, such as eggs, and their central role in health and well being of the animal, carotenoid content needs to be carefully monitored. Carotenoids are present in the animal kingdom, yellow, orange and red and are typically associated with birds such as seagulls and pink floyds. The colour carotenoids give to a numbers of birds affects some biological functions such as sexual behaviour and health indicators. The observation that many avian species in the wild naturally deposit very high concentrations of carotenoids into their yolks could imply that these pigments are there for a purpose. Amongst natural antioxidants, carotenoids play important roles in avian reproduction by maintaining antioxidant defences of the spermatozoa and embryonic tissues. Increased carotenoid concentration in the chicken embryo decreased the susceptibility of the tissues to lipid peroxidation. Dietary supplementation with antioxidants exerts a positive effect on fertility in aging hens by increasing their capacities for sperm retention at the sperm storage tubule level. Carotenoids in the diet of the laying hen are incorporated into the egg yolk and subsequently into the liver and other tissues of the chicken embryo. By transferring large amounts of dietary yellow and red carotenoids to the egg yolk, the mother provides protection for the developing embryo against oxidative damage. Indeed, eggs from wild birds contain carotenoid levels which are 3-10 times higher than the common levels in commercial eggs. In wild birds, loss of egg yolk or skin pigmentation is associated with disease, sickness or nutritional deficiencies. The antioxidant and immunostimulatory effects of carotenoids are especially important during the immediate post-hatch period, and important for the viability of the offspring. Maternal effects persist for at least the first week after hatching, thereafter the progeny’s diet becomes the main determinant of its carotenoid status. Since the antioxidant and immunostimulatory roles of carotenoids are likely to be especially important during the immediate post hatch period, maternal dietary intake of carotenoids may have important ramifications for the viability of the offspring.