β-Carotene-enriched Artemia as a natural carotenoid improved skin pigmentation and enhanced the mucus immune responses of platyfish Xiphophorus maculatus

The present study investigated the effects of enriched Artemia franciscana with beta-carotene of Dunaliella salina on color, skin carotenoid, and mucosal immune responses of platyfish, Xiphophorus maculatus. To this end, one hundred and eighty platyfish with an initial weight of 0.9 +/- 0.03 g were randomly assigned into four groups in triple and were daily fed on three times. The first and second groups were fed with commercial food (control) and unenriched A. franciscana (Un-EA), respectively. In addition, the third and fourth groups were fed with enriched A. franciscana with castor oil (oil-EA) and enriched A. franciscana with beta-carotene (beta-carotene EA) for 8 weeks, respectively. Based on results, the highest amount of carotenoids (112.4 +/- 22.79 mu g g(-1)) was significantly observed in the group fed with beta-carotene EA while the lowest amount (24.31 +/- 2.36 mu g g(-1)) was found in the group fed Un-EA. As regards lysozyme, total immunoglobulin, and alkaline phosphatase activity of the mucus, the highest amounts were detected in fish with beta-carotene EA as 84.5 +/- 19.09 mg dL(-1), 6.4 +/- 0.41 mg dL(-1), and 477 +/- 39.59 U L-1, respectively. Based on skin colorization results, the group fed with beta-carotene EA had no significant difference regarding the transparency, yellow color, and opacity, while a* index significantly increased in this group in comparison with the control group. However, the Hue index significantly decreased in the beta-carotene EA group compared with the control group. In conclusion, A. franciscana enriched with beta-carotene of D. salina enhanced the mucosal immune responses and improved the skin carotenoids as well as a* index in platyfish X. maculatus.