Dietary garlic supplementation positively affects the immunological system of juvenile cobia Rachycentron canadum reared in net pens during winter

Abstract

The objective of the present study was to evaluate the effect of garlic (Allium sativum) in the diet of juvenile cobia Rachycentron canadum reared in near shore net pens during winter in the coast of Rio de Janeiro (Brazil). Fish (172 ± 19 g and 31.1 ± 1.4 cm) were stocked in 6 cages (n=40 per cage). Two moist diets were prepared, a control diet without garlic and an experimental diet formulated to include 1% dry garlic. Fish were reared on these diets for 68 days, and at the end of the trial. Growth and survival were not affected by garlic inclusion (P>0.05). On the other side, significant differences (P<0.05) were observed for hematological and immunological parameters. The number of monocytes, thrombocytes, and the neutrophil:lymphocyte ratio were higher (P<0.05) in the control compared to the garlic supplemented diet. Whereas lymphocytes counting and phenotypic expression of lymphocyte receptors CD3 and CD4 were higher in diets containing garlic. Supplementation with 1% of garlic in the diet is recommended to boost the immune system and minimize stress of cobia juveniles farmed in near shore net pens during the winter.