Dietary sulfated polysaccharides extracted from Caulerpa sp. and Padina sp. modulated physiological performance, antibacterial activity and ammonia challenge test in juvenile rainbow trout (Oncorhynchus mykiss).

Nowadays, the use of seaweed derivatives in aquaculture has drawn attention for their potential as an immunostimulant and growth promotor. The sulfated polysaccharide extracted (SPE ) from green (Caulerpa sp.; SPC) and brown (Padina sp.; SPP) seaweeds with two concentrations (0.05% and 0.1%); nominated in four groups: SPC0.05 , SPC0.1 , SPP0.05 , SPP0.1 and control group (free of SPE ) were used for juvenile rainbow trout (Oncorhynchus mykiss) diet. Fish (N: 150; 8.5 ± 0.2 g) were selected aleatory distributed in 15 circular tanks (triplicate for the group) and fed test diets for 56 days. The outcomes revealed that the supplementation of SPE up to 1 g kg-1 failed to show significant differences in the organosomatic indices as compared to the control group. The most inferior protein value of dress-out fish composition was observed in the fish fed the control diet, which was statistically lower than the SCP0.1 group (p < 0.05), while no significant difference was observed in other macronutrient composition among the treatments. Total monounsaturated fatty acid (MUFA) had lower trend in the carcass of fish fed SPE supplemented diets, so that lowest MUFA were observed in SPC0.05 group (p < 0.05; 25.22 ± 4.29%). The lowest value of docosahexaenoic acid was observed in the control diet compared to the SPE -supplemented diets (p < 0.05). The serum alternative complement pathway levels in all treatments tend to promote compared to the control treatment. A similar trend was observed for lysozyme activity. According to the results, the superoxide dismutase (SOD) value were highest in SPC0.05 and SPC0.1 compared to the other treatments (p < 0.05), while a further elevation of the SPE Padina sp. extracted level (SPP0.1 ) leads to a decrease in SOD value. Thiobarbituric acid reactive substances of plasma was indicated not to influence by sulfated polysaccharide extracts in the refrigerated storage. The lowest serum stress indicators were observed in fish fed SPP0.05 group postchallenge test. Taken together, our outcomes revealed that SPE of two species of seaweeds bestows benefits in some of the immunity and antioxidant system. Also, notable elevations in HUFA were observed in juvenile rainbow trout fed supplemented with SPE .

Dietary effects of a low-molecular weight fraction (<10 kDa) from shrimp waste hydrolysate on growth performance and immunity of rainbow trout (Oncorhynchus mykiss): Employing nanodelivery systems.

Aquaculture by-products have been of great interest for producing protein hydrolysates with multiple biological activities. The present experiment was carried out to evaluate dietary effects of a low-molecular fraction (<10 kDa) from shrimp waste hydrolysate in forms of unprotected and nanocapsulated on growth and immunity of rainbow trout. Therefore, six diets were designed including a control diet (no supplementation), D1 (1 g kg-1 of unprotected fraction), D2 (1 g kg-1 chitosan nanocapsules), D3 (1 g kg-1 liposome nanocapsules), D4 (1 g kg-1 of fraction-loaded chitosan nanocapsules), D5 (1 g kg-1 of fraction-loaded liposome nanocapsules). Fish (0.91 ± 0.15 g) were fed with experimental diets until apparent satiation for six weeks followed by a 5-day experimental challenge with Streptococcus iniae. Results revealed that growth is strongly affected in fish receiving the fraction with D4 treatment showing the highest weight gain, SGR, final weight and the lowest FCR (p < 0.05). Nanocapsules without fraction did not show remarkable effects when compared to control group. In terms of serum and mucus immune parameters of lysozyme, complement activity, myeloperoxidase activity, and total protease, fish from D4 group showed the highest measured values followed by D5 (p < 0.05). Key immune related genes of IL-6 and TNF-α were noticeably up-regulated in fish from D1, D4, and D5 groups, which were consistent with survival rate after 5 days challenge with Streptococcus iniae. All together, the present findings highlighted the application of chitosan and liposome nanocarriers in aquaculture and potential of low-molecular weight fraction (<10 kDa) from shrimp wastes hydrolysate to improve growth performance and immune status of rainbow trout.

Effects of Lactobacillus rhamnosus ATCC 7469 on Different Parameters Related to Health Status of Rainbow Trout (Oncorhynchus mykiss) and the Protection Against Yersinia ruckeri.

In the current study, we investigated the effect of a probiotic bacterium (Lactobacillus rhamnosus ATCC 7469) microencapsulated with alginate and hi-maize starch and coated with chitosan on improving growth factors, body composition, blood chemistry, and the immune response of rainbow trout (initial weight: 18.41 ± 0.32 g). Four experimental diets were formulated to feed fish for 60 days. They were control diet without any additive (C), diet added with beads without probiotic (E), a probiotic sprayed to the diet (L.r), and encapsulated probiotic supplemented diet (E-L.r). The results indicated that feeding with E-Lr significantly improved weight gain (84.98 g) and feed conversion ratio (0.95) compared to the other groups (P < 0.05). Also, fish fed E-Lr diet had a significantly higher value of whole-body protein (17.51%), total protein in the blood (4.98 g/dL), lysozyme (30.66 U/mL), alternative complement pathway hemolytic activity (134 U/mL), superoxide dismutase (203 U/mg protein), and catalase (528.33 U/mg protein) (P < 0.05) as compared to those fed the control diet. Similarly, a higher relative expression of immune-related genes such as interleukin-1 (Il-1) and tumor necrosis factor-alpha (TNF-1α) were reported in those fed E-L.r and L.r diets respectively. Interestingly, the fish fed dietary E-L.r had a significantly lower value of lipid in the whole body (4.82%) and cholesterol in the blood (160.67%) in comparison with those fed the control diet (P < 0.05). At the end of the experiment, all groups were challenged by Yersinia ruckeri where the survival rate of rainbow trout fed dietary E-L.r (70.36%) was statistically higher than that of the others (P < 0.05). Overall, the results suggested that encapsulated probiotic Lact. rhamnosus ATCC 7469 acted better than unencapsulated probiotic and has a potential to improve growth performance, flesh quality, and the immune response of rainbow trout.