The present study investigated the effects of dietary prebiotic galactooligosaccharide [(GOS), 1%], probiotic (Pediococcus acidilactici) [7.57 log CFU g-1] and synbiotic (GOS + P. acidilactici) on antioxidant enzymes activity and disease resistance of rainbow trout (15.04±0.52 g). After 8 weeks feeding on the experimental diets, liver catalase (CAT ), glutathione S-transferases (GST), glutathione reductase (GR) activities, and malondialdehyde (MDA) levels were measured. Thereafter, all fish were challenged by Streptococcus iniae. Probiotic, prebiotic and synbiotic had no significant effect on liver MDA level compared to the control group (P>0.05). However, CAT , GST and GR activities were significantly higher in the fish fed probiotic, prebiotic and synbiotic, compared to the control group (P<0.05). The highest CAT and GST activities were observed in the fish fed diet supplemented with synbiotic. There were no significant differences in GR activity among different groups (P>0.05). Bacterial challenge showed that feeding on probiotic, prebiotic and synbiotic remarkably increased resistance against S. iniae (P<0.05), with the highest resistance observed in the synbiotic group. The results indicated that although both GOS and P. acidilactici significantly increased antioxidant defence and improved disease resistance, combination of GOS and P. acidilactici had an additive effect. Combination of GOS and P. acidilactici is recommended to increase trout antioxidant capacity and streptococcosis.
The present study investigated possible effects of dietary malic acid on the expression of immunity, antioxidant and growth related genes expression as well as skin mucus immune parameters in common carp. Common carp (Cyprinus carpio) fingerlings were fed diets supplemented with different levels (0 [control], 0.5%, 1%, 2%) of malic acid (MA) for 60 days. The results revealed highest expression levels of immune-related genes (tnf-alpha, il1b, il8 and lyz) in skin of common carp fed 2% MA (P < 0.05). Regarding 1% MA treatment comparison with control group, significant difference was noticed just in case of lyz (P < 0.05). Evaluation of growth related genes expression revealed no significant difference between treatments (P > 0.05). The study of antioxidant related genes (gsta and gpx) in common carp skin fed with MA, showed significant difference between treated groups and control (P < 0.05). Carps fed with 2% MA had highest alkaline phosphatase activity in skin mucus compared other treated groups and control (P < 0.05). There were no significant difference between 0.5% and 1% and control (P > 0.05). The study of total protein and total immunoglobulin (Ig) in common carp skin musus revealed no alteration following MA treatment (P > 0.05). The present data demonstrated that feeding with MA altered immune and antioxidant genes expression in skin mucus of common carp.
In this study, the basal diet was supplemented with ethanolic extract of purslane (Portulaca oleracea L.) and the possible effects on growth performance, anti-oxidative, and immune activities of grass carp were evaluated. Fish with initial weight 1.23 ± 0.11g were randomly divided into four groups (triplicates) and fed purslane extract at 0% (T0), 0.5% (T1), 1% (T2), and 1.5% (T3) for 56 days. At the end of the feeding trial, the results showed that growth parameters were enhanced in T1 groups compared to the control group (P<0.05). Lipase activity in T1 and T2 groups increased, whereas no significant changes were noticed in cases of amylase and protease activities (P>0.05). Catalase and superoxide dismutase activities were enhanced in all groups fed the supplemented diets in comparison with the control group (P<0.05). However, no significant alteration was noticed in the case of glutathione peroxidase activity following the administration of purslane extract (P>0.05). A significant increase in total immunoglobulin level was noted in the T1 group, but lysozyme activity was higher in T1 and T2 groups compared to the control group (P<0.05). In conclusion, supplementation of grass carp diet with the purslane ethanolic extract, especially at 0.5%, can improve growth performance, lipase activity, the antioxidant enzyme activities as well as the immune response of grass carp fingerlings.
The present study evaluated the effects of dietary inulin on growth performance, body composition, serum, biochemical, and mucus immune factors; as well as innate immune responses of rainbow trout fry challenged with Aeromonas hydrophila. Four diets were prepared using a commercially available fish feed as a basal diet and different levels of prebiotic inulin incorporation; 0 (control), 1, 2, and 3%; referred to as C, T1, T2, and T3, respectively. The findings of the 60-day feeding trial showed that inulin inclusion affected final weight, food conversion rate (FCR), and specific growth rate (SGR) compared to that of the control group (P < 0.05), in which the lowest FCR was observed in T3. Body composition analysis revealed that inulin significantly increased protein content and decreased lipid levels, especially in the T1 and T2 groups. The lowest ash level was noticed in T2 (P < 0.05). Blood total protein, albumin, globulin, cholesterol, and glucose were not affected by inulin supplementation (P > 0.05). Analysis of humoral immune responses showed that the inulin supplements significantly increased lysozyme and complement activities (P < 0.05), as well as higher red blood cell count (RBC) and hemoglobin (Hb) in fish, fed 2% inulin, while no significant differences were observed among other treatments (P > 0.05). The mucosal parameters; including lysozyme, alkaline phosphatase (excluding ACH50); protease activities; and total Immunoglobulin (IgM) improved significantly (P < 0.05), particularly in the T2 group. The T2 group also demonstrated the highest survival rate among all groups. The present findings indicate that dietary administration of inulin promotes growth and biochemical parameters, as well as serum immunity and mucosal immune responses of rainbow trout, in which a 2% inclusion produced the best results.
The present study investigated the possible effects of including salt of short chain fatty acid, sodium acetate (SA), on skin mucus immune parameters and immune, antioxidant and growth-related genes expression in common carp. There is a little data available about the effective role of SA on immune, antioxidant and growth related genes expression as well as skin mucus immune parameters. The aim of this study was to analysis the effect of SA intake on these factors using common carp (Cyprinus carpio) as model organism. Two hundred and forty healthy common carp (mean weight = 15 ± 0.9 g) supplied and randomly stocked into 12 fiberglass tanks 200 L (20 fish per tank) assigned to four treatments and triplicates. The study was performed in a completely randomized design. The treatments were feeding carps with experimental diets containing different levels (0.0 [control], 0.5, 1 and 2%) of SA. The skin mucus total immunoglobulin and total protein levels in fish fed 2% SA showed significant increase compared to the control group (P < 0.05). Results showed a significant increase in the GH gene expression in 1 and 2% SA treatments (P < 0.05). The carps were fed with diet content 2% SA showed significantly increase in IGF-1 expression (P < 0.05). The expression of GSTa, and GPX (antioxidant genes) revealed a significant increase in the GSTa (fish fed SA at 1% and 2% levels) and GPX gene expression with fish fed 2% SA (P < 0.05). Supplementation of fish diet with SA induce slight elevation in the intestine of all immune-related genes (TNF-α, IL-1β, IL8 and Lyz) compared to the control group (P > 0.05). However, Lyz gene significantly up-regulated in 1 or 2% SA treatments. These results confirmed beneficial effects of SA as a feed additive in common carp culture.