Dietary Synthetic Astaxanthin and Natural Astaxanthin From <i>Haematococcus pluvialis</i> and <i>Phaffia Rhodozyma</i> Improves the Growth, Antioxidant Capacity, Innate Immunity, and Pigmentation of Pacific White Shrimp ( <i>Litopenaeus vannamei</i>

This study evaluated the effects of dietary synthetic astaxanthin (SA), <i>Haematococcus pluvialis</i> (HP) and <i>Phaffia rhodozyma</i> (PR) on the growth performance, antioxidant activity, innate immunity, morphology, and pigmentation of juvenile <i>Litopenaeus vannamei</i>. Shrimp (1.15 ± 0.01 g) were fed with the control diet and astaxanthin diets containing 20 mg/kg of astaxanthin from three sources (SA, HP, and PR) for 56 days. The results indicated that, compared with the control group, growth performance was observably elevated in the HP and PR groups (<i>p</i> < 0.05). The astaxanthin (SA, HP, and PR) supplemented diets markedly elevated the activities of glutathione peroxidase (GPx) and GST in the intestine and hepatopancreas (<i>p</i> < 0.05), while observably reduced the MDA content (<i>p</i> < 0.05). The apoptosis rates in three astaxanthin groups were noticeably reduced in comparison with the control group (<i>p</i> < 0.05). Dietary astaxanthin (SA, HP, and PR) observably elevated the expression of the <i>Toll</i>, <i>IMD</i>, and <i>CAT</i> genes in the hepatopancreas (<i>p</i> < 0.05). Besides, dietary astaxanthin (SA, HP, and PR) noticeably improved the astaxanthin accumulation and pigmentation of shrimp (<i>p</i> < 0.05). The survival rates of shrimp challenged with <i>Aeromonas hydrophila</i> were markedly higher in the astaxanthin groups than in the control group (<i>p</i> < 0.05), and no significant difference was detected among three astaxanthin groups (<i>p</i> > 0.05). Moreover, our results suggested that natural astaxanthin (HP and PR) was more effective for enhancing growth and antioxidant capacity of shrimp. Nevertheless, no marked difference was detected between natural astaxanthin and SA in coloration performance and disease resistance.