Evaluating the possible feeding strategies of selenium nanoparticles on the growth rate and wellbeing of European seabass (Dicentrarchus labrax)

The study aimed at evaluating the possible feeding strategies of selenium (Se) nanoparticles on the performances of European seabass (Dicentrarchus labrax). The first group fed the basal diet continuously (control) while the second group offered Se (1 mg/kg diet) every day (R1). The third group fed the basal diet one day then Se diet every other day (R2), and the fourth group basal diet for two days then fed Se diet every two days (R3). The FBW, WG, and SGR were significantly improved in the R1 group than fish in the other groups (P < 0.05). The FCR was significantly reduced by feeding Se nanoparticles to fish in R1, R2, and R3 groups than the control with the lowest being in R1 group (P < 0.05). The R1, R2, and R3 groups had enhanced values of Hb, RBCs, and WBCs (P < 0.05). Additionally, the blood total protein and globulin of fish fed in R1, R2, and R3 groups was significantly higher than the control (P < 0.05). Phagocytic index, phagocytic, lysozyme activities were significantly higher in fish fed Se nanoparticles (R1, R2, and R3 groups) than fish fed the basal diets (P < 0.05). The anti oxidative related indices (SOD, CAT, and GPx) were enhanced in fish of R2 group while the concentration of MDA was reduced (P < 0.05). Further, the level of MDA was decreased in fish of R1 group that fed dietary Se nanoparticles every day. The relative expression of liver GH, IGF-1, IL-8, and IL-1 beta genes were significantly upregulated in fish of R1, R2, and R3 groups while HSP70 gene was reduced (P < 0.05). In conclusion, fish fed dietary Se nanoparticles at 1 mg/kg either daily, every other day, or every other two days had enhanced growth rate, feed efficiency, haemato-biochemical indices, immunity, antioxidative responses, and anti-inflammatory impacts on European seabass.