The Efficiency of Dietary Nano-Formulation of Laurencia obtusa Extract in Terms of the Growth Performance, Antioxidant Activity, and Immune Response of Juvenile Nile Tilapia (Oreochromis niloticus)

This study evaluated the effects of using Laurencia obtusa (L. obtusa) extract nanoparticles as a feed additive for the Nile tilapia (Oreochromis niloticus) juveniles. Four diets (30% protein) were prepared; three diets were supplemented with L. obtusa extract nanoparticles (LENPs) at concentrations of 0.25, 0.5, and 1 g kg−1, represented by LENP1, LENP2, and LENP3, respectively. The fourth diet served as the control. The fish, averaging 19.85 ± 1.35 g, were fed experimental diets for a duration of 60 days. The growth performance, antioxidant activity, immune parameters, digestive enzymes, and antioxidant and immune genes expression were evaluated. Results indicated that growth parameters were not affected by LENP incorporation compared to the control. All antioxidant biomarkers showed a significant increase in all groups compared to control, particularly LENP2 and LENP3, while levels of MDA and nitric oxide exhibited a considerable decrease in all groups than control. Concurrently, in terms of immunity impact, immunoglobulin levels exhibited substantial enhancement, as levels of IgM demonstrated significant increases, recorded maximum values in LENP2 and LENP1, respectively. Total protein, albumin, and globulin recorded the highest level in LENP3. Regarding blood indices, particularly RBC,s count, hemoglobin, packed cell volume (PCV) and mean corpuscular volume (MCV), all experimental groups showed a significant increase (P< 0.05) compared to the control.  Liver and kidney function exhibited non-significant changes compared to the control. Digestive enzymes values showed a significant rise compared to the control group. A substantial upregulation of GPX and SOD gene expression levels was recorded in LENP3 fed groups in both liver and spleen. A similar pattern was observed for interleukin1 beta (IL-1β) and interleukin-10 (IL-10), with elevated levels in the spleen compared to the liver. In conclusion, L. obtusa nanoparticles at different concentrations were effective in positively modulating O. niloticus physiological and immune parameters, with a non-significant effect on fish growth after 60 days feeding trial.