Influence of β‐glucan on innate immunity and resistance of Lutjanus guttatus to an experimental infection of dactylogyrid monogeneans

Abstract

The present study investigated the effect of β-1,3/1,6-glucan on growth, haematology, innate immunity and resistance against dactylogyrids on the spotted rose snapper (Lutjanus guttatus). Fish were fed during 5 weeks with commercial diet (control group) and same diet supplemented with three levels of β-glucans (0·05%, 0·1% and 0·5%/kg feed). The results showed that at concentrations of 0·05% and 0·1%, fish growth was enhanced, and in weeks 2 and 4, an increase in cellular responses such as percentage of monocytes, neutrophils, respiratory burst activity and nitric oxide activity was observed. In diet with 0·5%β-glucans, changes were registered at the end of the experiment. At week 2, 0·05%β-glucans showed the best response to most of the analysed parameters. In a second trial, diet with 0·05%β-glucans was chosen to prove its effect on the resistance of infected fish with monogeneans. The results showed that fish reduce significantly the number of dactylogyrids, and parameters such as WBC, percentage of lymphocytes, neutrophils and eosinophils were increased. In addition, WBC and percentage of thrombocytes increased in the control (+). The β-glucans have the potential to be use in diet formulations of the spotted rose snapper and to limit the adverse effects of dactylogyrids.

Effect of β glucan dietary levels on immune response and hematology of channel catfish Ictalurus punctatus juveniles

“…Results from this research show a general improvement in some hematological and immunological parameters after β-1,3/1,6 glucan intake, especially during weeks 3 and 4. However, some hematological parameters (Ht and RBC) showed opposed results decreasing over experimental time, agreeing with other studies (Del Rio-Zaragoza et al, 2011) which also reported high leucocytes values using same β-1,3/1,6 glucan concentration (0.05%) supplemented to red snapper Lutjanus guttatus commercial diet, and also a decrease in Ht and RBC values after the first treatment week.…”

“…No significant variation on total serum protein values during the experiment on any different diet groups were observed, which is similar to that reported in other species (Dicentrarchus labrax, L. guttatus) fed with β-1,3/1,6 glucan supplemented diets using similar concentrations (SitjÀ-Bobadilla & Pérez-Sánchez, 1999;Bagni et al, 2005;Del Rio-Zaragoza et al, 2011). No difference (P > 0.05) on glucose levels between treated and control fish were observed, suggesting a proper response from fish to biological modifiers like β-1,3/1,6 glucans.…”

“…β-glucans (1,3/1,6) have been widely used to stimulate innate immune response, and to improve parameters like phagocyte activity, respiratory burst activity, nitric oxide, complement and lysozyme activity, as well as to increase the number of leukocytes (Ringø et al, 2011;Bridle et al, 2005) on salt and freshwater fish, such as Atlantic salmon Salmo salar (Bridle et al, 2005); rose snapper Lutjanus guttatus (Del Rio-Zaragoza et al, 2011); sea bass Dicentrarchus labrax (Bonaldo et al, 2009); grass carp Ctenopharyngodon idella (Kim et al, 2009); rainbow trout Oncorhynchus mykiss (Jaafar et al, 2011) and Nile tilapia Oreochromis niloticus (Cain et al, 2003). In this regard, channel catfish Ictalurus punctatus also seems to respond to β-glucan immunostimulation when whole yeast cells have been used to improve its immune system (Welker et al, 2007).…”

Effect of β-Glucans in Diets on Growth, Survival, Digestive Enzyme Activity, and Immune System and Intestinal Barrier Gene Expression for Tropical Gar (Atractosteus tropicus) Juveniles

“…The ensuing diseases generate great economic losses during culture; therefore, the use of immunostimulants has increased in the aquaculture industry [21], with the prebiotic β-1,3/1,6-glucan being one of the most frequently used [31]. Under present experimental conditions, the incorporation of this prebiotic in balanced feeds designed for A. tropicus did not result in an improvement of the somatic growth parameters (body weight, length, SGR, FCR, and K).…”

“…Studies conducted on different fish species, such as Atlantic salmon (Salmo salar, Linnaeus 1758) [18], rainbow trout (Oncorhynchus mykiss, Walbaum 1792) [15,19,20], spotted rose snapper (Lutjanus guttatus, Steindachner 1869) [21], common carp (Cyprinus carpio, Linnaeus 1758) [16,22,23], roho labeo (Labeo rohita, Hamilton 1822) [13,24], gilthead sea bream (Sparus aurata Linnaeus 1758) [25], sea bass (Dicentrarchus labrax, Linnaeus 1758) [26,27], Nile tilapia (Oreochromis niloticus, Linnaeus 1758) [28], silver seabream (Pagrus auratus, Forster 1801) [12], large yellow croaker (Pseudosciaena crocea, Richardson 184) [29], and southern bluefin tuna (Thunnus maccoyii, Castelnau 1872) [30] have reported that β-glucans act by modulating different parameters of the immune response and increasing resistance to diseases [8,12]. Therefore, the objective of the present study was to determine the effect of different oral doses of β-1,3/1,6-glucan on growth, survival, digestive enzymatic activity, and the expression of several genes associated with the immune system and the intestinal barrier function in juveniles of the tropical gar (A. tropicus).…”