Exploring the effect of dietary nano selenium and/or Vitamin E and their interplay on reproductive physiology of Nile tilapia broodstock: Insights into spawning performance, haemato-biochemical profile, gene expression and gonadal architecture.

This research was conducted to explore the dietary effects of selenium nanoparticles (NSe), Vitamin E (VE) and their mixture supplementation on reproduction capacity, haemato-biochemical responses, spawning performance, gene expression and gonadal histology of Nile tilapia (Oreochromis. niloticus) broodstock. Fish brooders were allocated into four treatments in triplicates and served the formulated diets: basal diet (Control, G₀), 1 mg NSe kg⁻¹ (G₁),100 mg VE kg⁻¹ (G₂) and an inclusion of 1 mg NSe kg⁻¹ + 100 mg VE kg⁻¹ (G₃). Diets were fed to Nile tilapia (215 ± 34.56 g) stocked at a male: female ratio of 1: 3 for 60 days. The results revealed that hematological parameters (RBCs, WBCs, PCV, Hb), total protein, globulin and albumin were significantly increased (P < 0.05) in fish group fed dietary combination of 1 mg NSe kg⁻¹ + 100 mg VE kg⁻¹. While other indices (MCV, MCH, MCHC) remained unaffected among the different treated groups (P > 0.05). Optimum liver function enzyme activity and the highest reproductive hormones (MT, FSH, LH and progesterone) concentrations were found in the dietary inclusion of 1 mg NSe kg⁻¹ + 100 mg VE kg⁻¹. Organo-somatic indices, egg diameter and expression of reproductive genes (vasa, nanos1a, nanos2, dnd1, pum1, amh and VTG) are boosted (P < 0.05) in 1 mg NSe kg⁻¹ + 100 mg VE kg⁻¹ showing that this blend is required for the optimal reproductive capacity. Reproductive performance (mean fry number per female and mean fry weight) increased and gonadal architecture were improved in NSe-supplemented groups, with the highest recorded level in fish fed NSe/VE blend. In conclusion, our results revealed that dietary supplementation with 1 mg NSe kg⁻¹ and/or 100 mg VE kg⁻¹ can be effectively used for reproductive performance of Nile tilapia. The inclusion of NSe and VE at 1:100 mg/kg incorporated into fish diet seems to have a synergistic effect required for supporting haemato-biochemical indices and enhancing the overall spawning performance of Nile tilapia broodstock by increasing concentrations of sexual hormones, improving egg diameter, boosting gonadal puberty and up-regulating the expression of reproductive-related genes.