Optimal arachidonic acid supplementation enhances ovarian development and reproductive performance in female Redclaw crayfish (Cherax quadricarinatus)

Arachidonic acid (ARA) is an essential fatty acid for the gonadal development of aquatic animals. This study conducted a 10-week feeding trial to investigate the mechanism by which ARA modulates reproductive performance, focusing on its effects on ovarian development, lipid metabolism, steroid hormone synthesis, egg laying quantity, and nutrient deposition in eggs of female Cherax quadricarinatus broodstock. Five isonitrogenous (39 %) and isolipidic (9 %) diets with varying contents of ARA supplementation (0 % (Ctrl), 0.6 %, 1.2 %, 1.8 %, and 2.4 %) were formulated for female C. quadricarinatus broodstock (52.14 ± 0.25 g). Ovarian development and reproductive performance were evaluated after the 6th and 10th weeks of the trial, respectively. The results revealed that dietary 1.8 % ARA supplementation significantly enhanced the gonadosomatic index and increased the serum levels of progesterone and 17β-estradiol. Interestingly, the highest concentration of serum methyl farnesoate was observed in the control group. Histological analysis showed that 1.8 % ARA supplementation facilitated yolk granule deposition and accelerated oocyte maturation. Additionally, the 1.8 % ARA diet significantly improved the accumulation and transport of total cholesterol and triglycerides between the hepatopancreas and ovary. Serum metabolomics analysis indicated that arachidonic acid metabolism and neuroactive ligand–receptor interaction were significantly upregulated in the 1.8 % ARA group compared with the control. The relative contents of prostaglandin E₂, prostaglandin F_2α, and 14,15-deoxy-Δ12,14-PGJ₂ were notably increased. Moreover, dietary ARA supplementation significantly increased egg laying quantity and nutrient accumulation in fertilized eggs, with fatty acid deposition in the hepatopancreas, ovaries, and fertilized eggs being markedly influenced by dietary ARA levels. In conclusion, ARA supplementation in the diets of C. quadricarinatus broodstock improved lipid accumulation and steroid hormone synthesis by regulating prostaglandins, thereby promoting ovarian maturation and enhancing reproductive performance. The optimal dietary ARA addition for female C. quadricarinatus broodstock was determined to be between 1.675 % and 1.768 %.