A newly isolated strain of Haematococcus pluvialis JNU35 improves the growth, antioxidation, immunity and liver function of golden pompano ( Trachinotus ovatus )

The green alga Haematococcus pluvialis JNU35 is enriched in astaxanthin, linoleic acid and linolenic acid. H. pluvialis JNU35 can be used as an immunostimulant in aquatic feed. Here, the role of H. pluvialis JNU35 in mediating growth, antioxidation, immunity and liver function of Trachinotus ovatus was examined through feeding test. HP0, HP1 and HP5 diets containing 0, 10 and 50 g/kg H. pluvialis JNU35 were prepared for 6‐week feeding. It is shown that the supplement of H. pluvialis JNU35 in diet significantly triggers fish growth through elevating activities of digestive enzymes, food intaking, villus length and upregulating growth hormone and insulin‐like growth factor. H. pluvialis JNU35 supplementation protected from oxidative stress through the Nrf2‐ARE pathway and thus elevated activities of antioxidant enzymes. Meanwhile, H. pluvialis JNU35 supplementation protected liver function by declining lipid deposition, inhibiting hepatocyte apoptosis, upregulating anti‐inflammatory cytokines and downregulating pro‐inflammatory cytokines. Non‐specific immune ability of fish was also promoted by regulating expressions of complement 4, c‐type lysozyme and heat shock protein 70 in HP1 and HP5 diets. The blood health state of fish was improved by H. pluvialis JNU35 supplementation. In conclusion, H. pluvialis JNU35 promoted growth, antioxidation, immunity and liver function in T. ovatus .