Effect of including dried microalgae Cyclotella menegheniana on the reproductive performance, lipid metabolism profile and immune response of Nile tilapia broodstock and offspring

Cyclotella menegheniana is a diatom microalga often found in both marine and freshwater environments, characterized by a high-quality nutritional profile, including fatty acids, protein, and carotenoids, it is also a promising bioresource for improving food and animal feed nutrition. In this study, two separate experiments were conducted. In the first experiment, the utility of including C. menegheniana in the diet was evaluated for its impact on the reproductive efficiency, hematobiochemical biomarkers, and oxidative enzymes of broodstock Nile tilapia, Oreochromis niloticus, fish fed diet T2 (with 10 g kg(-1) C. menegheniana supplementation) recorded the highest (P < 0.05) gonadosomatic index (GSI) for female tilapia, whereas fish fed diet T3 (with 15 g kg(-1) C. menegheniana supplementation) recorded significantly higher (P <0.05) values of egg diameter, egg volume, sperm motility, and sperm concentration compared to the remaining dietary treatments. In addition of 15 g kg(-1) C. menegheniana significantly improved hemoglobin (Hb) and hematocrit (Htc) values of male and female broodstock. The content of triglyceride decreased in the blood of the broodstock fed diets supplemented with C. menegheniana. The lowest level of ALT and AST for male was observed in T3 group, while the highest one (P < 0.05) was in the control group. Complements component (C3), (C4) and IgM were significantly (P < 0.05) higher in fish fed diet T2 and T3 compared with other treatments. The final body weight, weight gain and specific growth rate of fries (F1 generation-II experiment) produced by fish received 15 g C. menegheniana significantly increased (P < 0.05), while fish received either 10 or 15 g C. menegheniana significantly improved (P <0.05) feed conversion ratio and protein efficiency ratio. In addition, fish received diets enriched with C. menegheniana significantly improved fry survival rate. In conclusion, the use of C. menegheniana as a feed additive stimulates the immune system and improves the blood and reproductive parameters of Nile tilapia broodstock, and it has a positive influence on the growth and feed conversion of Nile tilapia offspring