Retention of carotenoids in egg yolks of laying hens supplemented with heterotrophic Chlorella

Abstract

The present study investigated the effect of 1 and 2% feed supplementation with biomass of Chlorella grown through heterotrophic fermentation on the concentration of total and individual carotenoids in egg yolks. A total of twenty-four Hisex Brown laying hens aged 56 weeks were included in the experiment. The layers were kept individually in cages. They were divided into three groups of eight birds and fed a diet typical for laying hens. Control birds (C) received only a basal diet, while experimental diets (P1 and P2) were supplemented with 1 and 2% (i.e. 10 and 20 g/kg) dry disintegrated Chlorella biomass. Egg yolk deposition of total carotenoids was significantly (P < 0.01) increased by 46% (P1) and 119% (P2). The rising curves of total carotenoids reached their plateau during the fourth experimental week. The respective values oscillated around 25 mg (P1) and 40 mg (P2) per g of yolk during the following weeks. Lutein and zeaxanthin were equally deposited and they represented more than 90% of total carotenoids in yolk. The deposition of carotenoids significantly (P < 0.01) increased the colour characteristics of yolks measured using the Roche Yolk Colour Fan scale. Supplementation with Chlorella biomass significantly decreased the egg yolk weight of P2 in comparison with P1 (P < 0.05) and C (P < 0.01). These effects were probably related to lower feed consumption in these hens. The daily feed intake per hen, as well as its consumption per egg, was lower by 5–7 g in both supplemented groups. Recalculation of the diet consumption per kg of egg and yolk mass eliminated these differences. There were no differences among laying hens in plasma concentrations of triacylglycerol and cholesterol.