Dietary arachidonic acid improves the growth performance, anti-oxidant capacity and ovary development of female rice field eel broodstocks (Monopterus albus)

Arachidonic acid (ARA) is crucial for the growth, antioxidant capacity, and reproductive performance of fish. This study was conducted to assess the impact of dietary ARA on female rice field eel (Monopterus albus) broodstocks. A total of 600 eels, averaging 117.96 ± 3.65 g, were randomly distributed into 12 tanks, with each tank containing 50 fish. Four isonitrogenous and isolipidic diets comprising 0, 0.50%, 1.00%, and 1.50% ARA were formulated and fed to experimental fish for 10 weeks. Weight gain rates (WGR) increased significantly in 0.50% and 1.00% ARA groups compared to the control (ANOVA, P = 0.001; quadratic, P < 0.001). The lowest WGR and hepatosomatic index (HSI) values were observed in the 1.50% ARA group. Ovarian crude lipid content decreased in response to the increase of dietary ARA (P < 0.001). Serum alanine aminotransferase (ALT) activity was significantly reduced in 1.00% and 1.50% ARA groups (linear and quadratic, P < 0.01). Compared to the control, dietary addition of ARA up to 1.50% increased hepatic superoxide dismutase activity and decreased malondialdehyde content linearly and quadratically (P < 0.01). The ovarian ARA proportion was significantly increased in dietary ARA groups (P < 0.001). Dietary ARA increased the concentration of serum estradiol (E2), and contents of ovarian prostaglandin E2 (PGE2) and vitellogenin (VTG) (P < 0.05). The mRNA levels of ovarian cytochrome P450 (cyp19a1a), luteinizing hormone receptor (lhr), and hepatic vitellogenin (vtg) were significantly upregulated following ARA treatment (P < 0.05). In summary, dietary ARA supplementation increased the growth performance and ovarian deposition of ARA, and reduced the ovarian crude lipid content of M. albus. Dietary ARA may regulate the synthesis of steroid hormones and VTG by enhancing the PGE2 downstream signaling pathway, thereby promoting gonadal development in female M. albus broodstock. The optimal dietary ARA supplementation for female M. albus broodstock is suggested to be 10.00 g/kg.