The present research was conducted to assess the influences of
starvation and refeeding on growth, nonspecific immunity and
lipid metabolic adaptation in Onychostoma macrolepis. To date, there have been no similar reports in O. macrolepis. The fish were randomly assigned into two groups: control group (continuous feeding for six weeks) and starved-refed group (
starvation for three weeks and then refeeding for three weeks). After three weeks of
starvation, the results showed that the
body weight (BW, 1.44 g), condition factor (CF, 1.17%), visceral index (VSI, 3.96%), hepatopancreas index (HSI, 0.93%) and intraperitoneal fat index (IPFI, 0.70%) of fish were significantly lower compared to the control group (BW, 5.72 g; CF, 1.85%; VSI, 6.35%; HSI, 2.04%; IPFI, 1.92%) (p < 0.05). After
starvation, the serum
triglyceride (TG, 0.83 mmol/L), total
cholesterol (T-GHOL, 1.15 mmol/L),
high-density lipoprotein (HDL, 1.13 mmol/L) and
low-density lipoprotein (
LDL, 0.46 mmol/L) concentrations were significantly lower than those in the control group (TG, 1.69 mmol/L; T-GHOL, 1.86 mmol/L; HDL, 1.62 mmol/L;
LDL, 0.63 mmol/L) (p < 0.05). The activities of intestinal digestive
enzymes (
amylase,
lipase and
protease) in the starved-refed group were significantly lower than those in the control group after three weeks of
starvation (p < 0.05). The highest activities of immune
enzymes such as
lysozyme (LZM),
acid phosphate (ACP), alkaline
phosphate (ALP),
superoxide dismutase (SOD),
glutathione peroxidase (GSH-PX) and
catalase (CAT) in the hepatopancreas were presented in the starved-refed group at second week, and significantly higher than those in the control group (p < 0.05). Meanwhile,
starvation significantly improved intestinal immune
enzymes activities (p < 0.05). the lowest TG contents and the highest expression levels of lipolysis genes including
hormone-sensitive lipase (HSL) and
carnitine palmitoyl
transferase 1
isoform A (CPT-1A) appeared in the hepatopancreas, muscle and intraperitoneal fat after
starvation, indicating the mobilization of fat reserves in these tissues (p < 0.05). After refeeding, the recovery of TG content might be mediated by the upregulation of the expression levels of lipogenesis genes such as
sterol regulatory element binding protein 1 (SREBP1) and
fatty acid synthase (FAS). Understanding the duration of physiological and metabolic changes in O. macrolepis and their reversibility or irreversibility to supplementary feeding response could provide valuable reference for the adaptability of O. macrolepis in large-scale culturing, proliferation and release.