Oral administration of Sargassum polycystum extracts stimulates immune response and increases survival against Aeromonas hydrophila infection in Oncorhynchus mykiss

Sargassum sp. extract improve hematological profile of tilapia fish ( Oreochromis niloticus)

Background: Strategies to increase body resistance and prevent disease in aquaculture include using vaccines, antibiotics, and probiotics. Today, the use of antibiotics with natural ingredients is becoming a trend. One of the natural ingredients that contain high antioxidants and antibiotics is Sargassum sp. Methods: This research was conducted from March to May 2022 at the Biotechnology Laboratory, Faculty of Fisheries and Marine, Universitas Riau, in two stages: 1) the sensitivity of extracts of Sargassum sp. and 2) the application of Sargassum sp. extract orally in tilapia ( O. niloticus). The parameters measured were clear zone, minimum inhibitory concentration, LD 50 test of leaf extract of Sargassum sp. in tilapia ( O. niloticus), hemoglobin levels, hematocrit, total leukocytes, total erythrocytes, leukocyte differentiation, and survival rate. Data on hematology parameters were tabulated and analyzed using a One-Way ANOVA followed by a Student Newman Keuls (SNK) test when deemed necessary. Results: The results showed that the extract of Sargassum sp. inhibited the growth of Aeromonas hydrophila bacteria with a clear zone of 6.5-15.0 mm, which is classified as resistant. At doses of 2000, 2500, and 3000 ppm, it did not cause death in fish for 96 hours (LD 50). Hematological parameters can be a sign of the health status of fish. Tilapia given Sargassum sp. in different doses gave an effect between treatments, both after 30 days of rearing and post-test against A. hydrophila bacteria (p<0.05). The results showed that the hematology of fish fed with Sargassum sp. extract was in the normal or healthy range. Healthy tilapia had erythrocyte counts ranging from 1.34-2.11×10 6 cells/mm 3, hematocrit 26.17-33.19%, hemoglobin 6.26-11.2 g/dL and total leukocytes 1.01-1.50×10 4 cells/mm 3 and total erythrocytes 5.88-9.13×10 4 cells/ mm 3. Conclusions: A dose of 3000 ppm provided the highest health improvement against A. hydrophila bacterial infection.

Dietary flaxseed (Linum usitatissimum) oil supplementation affects growth, oxidative stress, immune response, and diseases resistance in rainbow trout (Oncorhynchusmykiss)

This paper describes the effects of flaxseed (Linum usitatissimum) oil (FSO) as a feed additive on growth performance, oxidative stress, immunity, and disease resistance in rainbow trout (Oncorhynchus mykiss). Four-hundred-and-twenty rainbow trout individuals (mean weight: 25.66 ± 1.33 g) were fed with different doses of FSO (0.5, 1, and 1.5%) ad libitum two times a day for 9 weeks. At the end of the feeding, growth performance was evaluated and the fish were challenged with two different bacteria (Yersinia ruckeri and Aeromonas hydrophila). At the end of the 3rd, 6th, and 9th weeks, blood and tissue samples were collected from 9 fish per treatment to evaluate innate immune response, cytokine gene expression levels, antioxidant enzyme activities and lipid peroxidation levels, and digestive enzyme activities. Determination of haematological parameters and histological examination was also carried out to evaluate the general health status of the fish. Results showed that the final weight and specific growth rate of fish supplemented with FSO increased significantly (p < 0.05). FSO-supplemented fish showed higher resistance to Y. ruckeri infection than the control group (p < 0.05). However, survival rates of all groups in A. hydrophila challenge test were similar (p > 0.05). Among the investigated innate immune response parameters, the potential killing activity of phagocytes, myeloperoxidase activity, and lysozyme activity increased in the FSO-supplemented groups (p < 0.05). Almost all cytokine gene expression levels in the experimental groups up-regulated especially after 9 weeks of feeding in the head kidney and intestine (p < 0.05). Similarly, superoxide dismutase and catalase activities were found to be significantly higher in the FSO group than in the control (p < 0.05) whereas, the lipid peroxidation levels drastically declined as a result of the FSO supplementation (p < 0.05). These results suggest that FSO can improve growth, enhance immune response, and lower oxidative damage in rainbow trout when supplemented at the rates of 0.5-1.5% for 9 weeks.

Effect of dietary celery (Apium graveolens) on the growth performance, immune responses, and bacterial resistance against Vibrio anguillarum of European seabass (Dicentrarchus labrax)

In this study, we evaluated to reveal the effects of aqueous methanolic extract of celery (Apium graveolens) on the growth performance, immune responses, and resistance against Vibrio anguillarum in European seabass (Dicentrarchus labrax). For this purpose, twenty fish (initial mean weight of 4.80 ± 0.06 g) were placed into twelve tanks (400 L) in triplicate and fish were fed with control (C) and three different levels (0.01, 0.05, and 0.1 g/kg) of A. graveolens (AG) extract-containing diets (AG0.01, AG0.05, and AG0.1) for 30 days. Blood and tissue (kidney, spleen, and intestine) samples were taken from the fish every 10 days during the study to determine the immune responses of the fish. Respiratory burst activity (RBA) was significantly decreased in the AG0.1 group compared to all other groups on the 10th day of the study (P < 0.05). Significance was noticed in the RBA of fish in all AG groups compared to the C group (P < 0.05) on the 30th day of the experiment Lysozyme activity (LYS) was raised on the 10th day of the study in all celery groups compared to the C group (P < 0.05). No differences in the myeloperoxidase activity (MPO) were observed among the experimental groups (P > 0.05). The final mean weight (FMW) was not affected in any experimental groups (P > 0.05). However, in the AG0.05 group, the specific growth rate (SGR) increased, and the feed conversion ratio (FCR) decreased compared to other groups (P < 0.05). IL-1β in the kidney was highly elevated in the AG0.01 group on the 20th day of the study (P < 0.05). Similar results were observed on IL-6, IL-8, and TNF-α expression in the kidney (P < 0.05). Anti-inflammatory responses (IL-10 and TGF-β) also increased in all experimental groups and tissues compared to the C group (P < 0.05). COX-2 was upregulated on the 20th day of the study in all tissues (P < 0.05). At the end of the feeding trial, the survival rate of the AG0.1 group in fish infected with Vibrio anguillarum infection was higher than the C group. Dietary celery extract did not affect growth performance directly but increased innate immune responses and a high survival rate. Overall, compared to the control group, the growth, immunity, and resistance of European seabass fed with a diet containing 0.05 g/kg celery aqueous methanolic extract has been improved, and this could be used as an immunostimulant feed additive.

Cylindropuntia cholla aqueous root rich in phytosterols enhanced immune response and antimicrobial activity in tilapia Oreochromis niloticus leukocytes

"Cacti" are rich sources of phytochemicals with antioxidant activity, and their use is mainly focused on infusions in traditional medicine in Mexico. This study characterizes the chemical compounds found in Cylindropuntia cholla root by gas chromatography coupled to mass spectrometry (GC-MS) and determines the total content of polyphenols and flavonoids, as well as their antioxidant capacity. The immunostimulatory effect of aqueous C. cholla root extract (ACcr) was evaluated at concentrations of 50, 250, 500, and 1000 μg/mL in Tilapia peripheral blood leukocytes. The results obtained by the GC-MS analysis revealed the presence of phenolic acids, flavonoid and phytosterol derivatives as β-sitosterol and campesterol. The determination of the total polyphenol and flavonoid contents indicated that ACcr is abundant in polyphenols, showing an anti-radical capacity of scavenging free radicals, such as those of hydroxyl and superoxide, as well as an increase in lipid peroxidation inhibition capacity. Stimulation of tilapia leukocytes resulted in the increase of its phagocytic activity, respiratory burst, nitric oxide production, and superoxide dismutase activity. Finally, the results obtained for the first time allowed establishing the chemical profile of ACcr and its antimicrobial activity against three important pathogenic bacteria. The potential of this root is indicated as an additive in formulating antioxidant and immunostimulant supplements for the aquaculture and pharmaceutical industry.

Effects of white mustard (Sinapis alba) oil on growth performance, immune response, blood parameters, digestive and antioxidant enzyme activities in rainbow trout (Oncorhynchusmykiss)

A study was conducted to evaluate the effects of dietary supplementation of white mustard (Sinapis alba) oil (WMO) on growth performance, immune responses, digestive and antioxidant enzyme activities in juvenile rainbow trout (Oncorhynchus mykiss). For this purpose, fish (initial weight: 25.77 ± 0.13 g) were divided into four experimental groups in triplicate and fed ad libitum twice a day with diets containing WMO at 0 (control), 0.5, 1, and 1.5% of diet for 9 weeks. Three fish from each tank (n:9 per treatment) were sampled on 21st, 42nd, and 63rd days for further analyses. At the end of the feeding period, fish were challenged with Aeromonas hydrophila and Yersinia ruckeri in two separate experimental setups. Results showed that final weight, weight gain, and specific growth rate were significantly increased in all experimental groups compared to the control. Feed conversion ratio was similar among treatments. Respiratory burst and potential killing activity decreased in all experimental groups compared to the control (P < 0.05). Lysozyme and myeloperoxidase activities were elevated in all experimental groups at the end of the experiment compared to the control (P < 0.05). Cytokine gene expressions in the head kidney and intestine were elevated in all experimental groups compared to that of the control in general (P < 0.05). Hematological responses of the experimental fish groups were similar to that of the control (P > 0.05). Pepsin and trypsin levels decreased in all experimental groups (P < 0.05). In terms of antioxidant enzyme activities, significant improvement in liver superoxide dismutase, catalase, and glutathione s-transferase activities in all treatment groups were determined (P < 0.05). In addition, a significant decline in liver lipid peroxidation levels was recorded in all treated groups at all sampling times compared to the control (P < 0.05). At the end of this feeding trial, no significant differences (P > 0.05) were observed in survival against A. hydrophila among experimental groups compared to the control (P > 0.05). However, increased survival against Y. ruckeri was determined in experimental fish groups (P < 0.05). This study suggests that white mustard oil had a favorable effect on the overall health and growth of rainbow trout.

Effects of dietary marine sulphated polysaccharides (Algimun®) on growth performance, immune responses and disease resistance of juvenile gilthead seabream (Sparus aurata) to Photobacterium damselae subsp. piscicida

The present study evaluated the effects of a dietary mix of marine sulphated polysaccharides, named Algimun® (AL), supplementation to gilthead seabream (Sparus aurata) juveniles in terms of growth performance, immune responses, and resistance against Photobacterium damselae subsp. piscicida. A total of 240 fish (initial mean weight of 6.00 ± 0.03 g) was randomly separated into 12 tanks (400 L, 20 fish per tank) distributed in four replicates. Fish were fed three experimental diets: a basal diet (Control), and a basal diet with two inclusion rates of Algimun® as 3 g/kg (AL0.3) and 5 g/kg (AL0.5) for 30 days before bacterial infection with P. damselae subsp. piscicida. After a 30-day feeding-period, growth performance was significantly improved in AL0.3 and AL0.5 groups compared to the control group (P < 0.05). AL0.3 and AL0.5 groups showed significantly higher lysozyme activity and myeloperoxidase activity when compared to the control group (P < 0.05). The gene expression of immune mediators (IL-1β, IL-6, IL-10, IL-18, TNF-α and COX-2) was significantly upregulated in the intestine, spleen and head kidney in AL0.3 and AL0.5 groups when compared to the control group (P < 0.05). Eight days post-challenge, the survival rate against P. damselae subsp. piscicida was numerically higher in fish within AL0.3 and AL0.5 groups compared to control (+20%). The study findings suggest that marine sulphated polysaccharides (Algimun®) could be used as an immunomodulator in gilthead seabream to support animal's health and boost resistance in case of disease outbreak.

Effects of dietary Astragalus caudiculosus (Boiss & Huet, 1856) supplementation on growth, hematology, antioxidant enzyme activities, and immune responses in rainbow trout (Oncorhynchus mykiss Walbaum, 1792)

The potential dietary utilization of Astragalus caudiculosus (AC) in rainbow trout (Oncorhynchus mykiss) was investigated. Four different fish groups (control, AC1, AC2.5, and AC5) were assigned and received the AC-containing diet for 90 days at the rates of 0, 1, 2.5, and 5%, respectively. Results indicated that the growth performance of the AC supplemented fish improved significantly (P < 0.05). Among non-specific immune parameters examined, while lysozyme activity of the AC supplemented fish increased (P < 0.05), oxidative radical production decreased in AC1 and AC2.5 fish groups (P < 0.05) but did not differ in the AC5 group (P > 0.05) compared to the control. Moreover, myeloperoxidase activity was not affected by the AC supplementation (P > 0.05). All pro-inflammatory and anti-inflammatory cytokine gene expressions, except IL-1β, were up-regulated, especially in the fish groups fed with 2.5 and 5% AC supplemented feed (P < 0.05). AC administration caused an elevation in GPx and G6PDH activities, and a decrease in SOD, CAT, and lipid peroxidation (P < 0.05). Overall, AC extract was found to improve the growth, antioxidant status, and immune response of the fish.