Optimisation of Dietary Lipid in Genetically Selected Clarias magur in Term of Gonadal Growth, Reproductive Performance, and Expression of Reproduction-Related Genes.

A 90-day feeding trial was conducted in magur broodstocks (both male and female) using five iso-nitrogenous (36.14% CP), hetero-lipidic (4%-12%), and hetero-energetic (387.02-426.88 Kcal/100 g) semi-purified experimental diets: L4 (4% lipid), L6 (6% lipid), L8 (8% lipid), L10 (10% lipid), and L12 (12% lipid), each tested in triplicate. Gonadosomatic index (GSI) increased with dietary crude lipid (CL) up to 10%, peaking in the L8 and L10 groups before declining. Absolute fecundity was highest in L10, while relative fecundity peaked in L8. Visceral fat index (VFI) also increased with CL, reaching the highest levels in L10 and L12. Reproductive performance parameters, including egg weight and diameter, improved with increasing CL, with significantly higher values observed from L6 to L12. The Fertilisation (%) and hatching (%) rates were highest (p < 0.05) in the L8 and L10 groups. Third-day larval survival was greatest in L8, while seventh-day survival was significantly higher (p < 0.05) in both L8 and L10 groups. In females, serum glucose and Triacylglycerol (TAG) levels increased with higher lipid intake, peaking in the L10 and L12 groups, while the lowest values were recorded in L4. Estradiol and 11-keto testosterone (11-KT) levels remained unaffected (p > 0.05), whereas 17α, 20β-dihydroxy progesterone (17α,20β-DHP) increased significantly (p < 0.05) up to the 10% lipid-fed groups. Female follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) gene expressions were unchanged, but in males, FSHR expression peaked in L6 to L12, and LHR in L6 to L10. Cytochrome P450 aromatase (CYP19a1) expression was significantly higher (p < 0.05) in L6 and L8. Regression analysis indicated that the optimal dietary CL level for Magur broodstock, based on reproductive performance, ranges between 8.32% and 8.58%.