Effects of natural and synthetic immunostimulants on growth, feed utilization, immune status, and disease resistance against vibriosis in sea bream (Sparus aurata)

Abstract

The objective of this study was to explore the effects of black seed (Nigella sativa) and AQUA-IMMUNOPROTECT® on growth, feed utilization, serum constituents, and disease resistance against vibriosis in gilthead sea bream juveniles. The research involved three groups: TC (control) received a basal diet, TSI (received a basal diet with 2% AQUA-IMMUNOPROTECT®), and TNS (received a basal diet with 2% N. sativa). The experiment period extended for 2 months. Results revealed a significant rise in erythrogram (RBCs, HB, and PCV %), leucogram (total differential leucocytic count), serum total protein, and globulin in gilthead sea bream treated with 2% Nigella sativa supplemented diets after an 8-week trial. No substantial variations were found in liver enzymes, urea, uric acid, and creatinine between the groups. Respiratory burst activity was notably greater in the N. sativa group after 2 months of feeding compared to the other groups. In the experimental challenge, the control group experienced higher mortality rates than the other groups following an IP injection of V. harveyi at a dose of 106 CFU per 0.5 ml/fish (106 fish/challenge). Overall, the findings of this research indicate that N. sativa can enhance non-specific immunity and minimize susceptibility and pathogenicity to V. harveyi in gilthead sea bream.