Effect of Diet Supplemented with Nano-Selenium on Reproductive Performance, and Sexual Hormones, Pathological Response of Nile Tilapia (Oreochromis niloticus).

This research aimed to examine the effects of different dietary levels of nano-selenium (NSE) on the reproductive performance, gonad hormones, histopathology, growth performance, feed utilization, and body indices in adult Nile tilapia, Oreochromis niloticus, broodstock for 90 days. The initial weights of the fish were 278.6 ± 5.5 (males) and 178.4 ± 1.6 (females). They were distributed randomly to 15 tanks with 20 fish in each tank (15 females and 5 males, sex ratio 3:1), with each treatment conducted with three replicates. The contents of NSE in five isocaloric and isonitrogenous practical feeds were 0 mg/kg (control), 1 mg/kg (T1), 2 mg/kg (T2), 3 mg/kg (T3), and 4 mg/kg (T4). Results show that the final weight (FW), weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), and feed conversion ratio (FCR) were significantly better in T2 and T1, followed by the control, in comparison with others. On the other hand, growth efficiency was decreased in T3 and T4 of both males and females. Referring to body indices and reproductive performance, females were higher than males in the hepatosomatic index (HSI), where the lowest treatment was the control and T4 for both males and females. Female Nile tilapia brood fish given NSE improved reproductive performance indicators (egg number, total egg, and fry number) when compared with the control. With increasing levels of NSE in the feed, the levels of testosterone and progesterone hormones were increased. The highest values for testosterone were in T4, followed by T3, then T2, T1, and the control. The same trend was observed across the progesterone treatments. Additionally, the results of histopathological examination indicate differences in tissues between different treatments as a result of the addition of NSE. These results indicate that NSE supplementation at low levels could lead to improved growth and reproductive efficiency of Nile tilapia.