Possibility of Using Astaxanthin-Rich Dried Cell Powder from Paracoccus carotinifaciens to Improve Egg Yolk Pigmentation of Laying Hens

The study investigated egg quality aspects such as astaxanthin concentration, E/Z-isomer ratio, and yolk color in laying hens fed with astaxanthin-containing diets. Dried Paracoccus carotinifaciens cell powder (Panaferd-AX) and fine cell powder (Panaferd-P) were used as sources of astaxanthin, with average particle diameters of approximately 100 μm and 10 μm, respectively. Paracoccus carotinifaciens contains valuable rare carotenoids such as adonirubin and adonixanthin, and thus the concentrations of these carotenoids in egg yolk were also evaluated. The E/Z-isomer ratios of the egg yolk carotenoids were determined by normal-phase high-performance liquid chromatography (HPLC) with an improved solvent system. Feeding diets containing P. carotinifaciens resulted in increased concentrations of astaxanthin, adonirubin, and adonixanthin in egg yolk, as well as a marked increase in the yolk color fan score; values associated with the Panaferd-P-containing diet were higher than those associated with the Panaferd-AX-containing diet. For example, the astaxanthin concentration in egg yolks of hens fed with the Panaferd-AX- and Panaferd-P-containing diets for 21 days were 1.21 μg/g and 1.85 μg/g, respectively. This indicates that the pulverization treatment of the P. carotinifaciens powder increased the efficiency of carotenoid accumulation in the egg yolk. Moreover, more than 95% of astaxanthin in P. carotinifaciens was present as the all-E-isomer. However, approximately 25% of astaxanthin in egg yolk was present as the Z-isomers. In recent years, astaxanthin Z-isomers have attracted substantial attention as they exhibit a greater bioavailability and bioactivity than the all-E-isomer. These data are important not only for understanding egg yolk pigmentation but also for improving the nutritional value of hens’ egg yolk through the addition of P. carotinifaciens to their diet.