Effect of alkoxy glycerol on growth performance, immune response and disease resistance in Nile Tilapia (Oreochromis niloticus)

Effects of Bacillus subtilis as a single strain probiotic on growth, disease resistance and immune response of striped catfish (Pangasius hypophthalmus)

The present study investigated the potential role of Bacillus subtilis as probiotic in striped catfish (Pangasius hypophthalmus). Fish (initial weight = 150.00±2.63g n = 180) were stocked in circular tanks. Four isonitrogenous (30%) and isolipidic (3.29%) diets were formulated having supplementation of B. subtilis at four different levels (P0; 0, P1: 1×106, P2: 1×108 and P3: 1×1010 CFU/g). Each treatment had three replicates, while each replicate had fifteen fish. The trial started on second week of July and continued for eight weeks. Growth, feed conversion ratio, crude protein content, the concentration of amylase and protease, the profile of both dispensable and non-dispensable amino acids in all four dietary groups increased with a gradual increase of B. subtilis in the diet. At the end of growth experiment, fish in all four groups were exposed to Staphylococcus aureus (5×105 CFU/ml). After S. aureus challenge, fish fed with B. subtilis responded better to damage caused by reactive oxygen species and lipid peroxidation and better survival rate. The catalase and superoxide dismutase level also increased in response to bacterial challenge in B. subtilis fed groups. On the other hand, the concentration of malondialdehyde gradually decreased in these groups (+ve P0 >P1>P2>P3). It is concluded that supplementation of B. subtilis as a probiotic improved the growth, protein content, antioxidant response and immunocompetency against S. aureus in striped catfish. The optimum dosage of B. subtilis, at a concentration of 1×1010 CFU/g, resulted in the most favorable outcomes in striped catfish. This single bacterial strain can be used as an effective probiotic in large scale production of aquafeed for striped catfish. Future studies can investigate this probiotic's impact in the intensive culture of the same species.

Evaluating local strains of soybean and corn cultivars in the diets of Nile tilapia (Oreochromis niloticus): growth and insulin-like growth factor 1, intestinal health, and inflammation features

Recently, the high cost of aquafeed affected fish farming feasibility in some countries, including Egypt. The imported soybean meal and corn ingredients consume a large amount of the hard currency, thereby increasing feed prices. Thus, the current study investigated the different sources of soybean and corn on the performances of Nile tilapia. Fish fed with the diet I (based on Egyptian soybean meal cultivar and cornmeal cultivar) or diet II (based on imported soybean meal cultivar and cornmeal cultivar) in a 90-day feeding trial. The results showed no marked effects on the growth performance, protein efficacy ratio, and FCR in the case of fish-fed diet I or diet II. No histological alterations were observed in the skeletal muscle, hepatopancreas, spleen, and intestines, while the diet I-fed group showed normal architecture of the above-listed organs. The expression of liver and muscle IGF-1 showed no changes in fish-fed diet I or diet II. No diet-related variations were observed in IL-1β expression in the spleen but increased regulation in the liver of the diet II group compared to the diet I group. Furthermore, significant upregulation of SOD and HSP70 genes were seen in the spleen and liver of the diet II-fed group. We conclude that the inclusion of the Egyptian soybean meal cultivar and cornmeal cultivar (diet I) did not reduce the growth performance and immune-related genes compared with the imported soybean meal cultivar and cornmeal cultivar (diet II).

Effect of diet enriched with Agaricus bisporus polysaccharides (ABPs) on antioxidant property, innate-adaptive immune response and pro-anti inflammatory genes expression in Ctenopharyngodon idella against Aeromonas hydrophila

The effect of Agaricus bisporus polysaccharides (ABPs) supplemented diet on growth rate, antioxidant capacity, innate-adaptive immune response, proinflammatory and antiinflammatory genes expression in Ctenopharyngodon idella against Aeromonas hydrophila is reported. In both normal and challenged groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets resulted in a significant weight gain and feed intake. The survival was 100% in normal fish fed without or with any ABPs diet; the challenged fish fed with 1.0 mg kg^-1 ABPs diet had 98.6% survival. The RBC and WBC counts, Hb, and Hct levels were significant in both normal and challenged groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets. A significant increase in total protein and albumin level was observed in both groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets. Significant increase in GPx, ROS, GR, GSH, PC, and MnSOD activity was observed in HK of both groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets; similarly both groups when fed with the same ABPs diets showed significant Lz, C3, and C4 activity. However, both groups fed with 1.0 mg kg^-1 ABPs diet showed significant β-defensin, LEAP-2A, IL-6, and NF-κB P65 mRNA expression. Similarly, IFN-γ2, IL-10, and TNFα mRNA expressions were significant in both groups fed with 1.0 mg kg^-1 ABPs diet. The results indicate that both normal and challenged C. idella fed with a 1.0 mg kg^-1 ABPs diet had better growth, antioxidant status, immune response, and pro-anti-inflammatory gene modulation against A. hydrophila.

Effects of Dietary Bovine Lactoferrin on Growth Performance and Immuno-physiological Responses of Asian Sea Bass (Lates calcarifer) Fingerlings

The aim of this study was to evaluate the effects of lactoferrin (Lf) on growth and feeding performance, biochemical and immune parameters in Asian sea bass (Lates calcarifer). A basal diet was supplemented with 0 (control), 400 (400 Lf), or 800 (800 Lf) mg Lf kg^-1 diet. The results indicate a significant increase in innate immune parameters when the diet was supplemented with 800 mg Lf kg^-1. The highest serum albumin value and the lowest serum glucose concentration were observed in 800 Lf group. The liver catalase activity in the 400 Lf and 800 Lf groups was lower than the control value. Moreover, malondialdehyde concentration in the liver of Asian sea bass was increased with increasing the dietary Lf supplementation. The results of the study suggest that supplementing diet with 800 mg Lf kg^-1 stimulates non-specific immune response in Asian sea bass. Nonetheless, selecting an appropriate dose can be difficult, especially since both the higher and the lower dose tested may result in adverse effects.

Inherent immunological parameters in kutum, Rutilus frisii, larvae obtained from the adult females with orange and green eggs

Kutum (Rutilus frisii) displays different egg colours during the spawning season, mostly due to the presence of carotenoid pigments. In this study, the authors investigated the relationship between the egg colour and muscle lipid of adult female kutum and the correlation between egg carotenoid content and the immune parameters of larvae. The results from this study highlighted the positive influence of egg carotenoid on post-fertilization stages, such as elevating the innate immune parameters in larvae.

Shrimp lectin (Md-Lec) conjugated copper sulfide nanoparticles enhance the elimination of aquatic pathogens in infected Nile tilapia (Oreochromis niloticus)

Lectins are known for their ability to bind to cell surface glycans, and are useful to develop a glycan-targeted drug delivery system. This study aimed to evaluate the capacity of pectin capped copper sulfide nanoparticles (pCuS NPs) to modulate the antibacterial activity of a lectin, Md-Lec, purified from the shrimp, Metapenaeus dobsoni. Fluorescence spectroscopy revealed that Md-Lec has the ability to form a complex with pCuS NPs. Haemagglutination assay showed that the carbohydrate binding site of the lectin was preserved even after complexing with pCuS. The minimum inhibitory concentrations (MICs) obtained for Md-Lec and pCuS NPs against the tested aquatic pathogens were 50 μg ml-1 and 12.5 μM, respectively. Interestingly, the MIC of Md-Lec-pCuS NPs complex was four fold lower than that of pCuS, which was attributed to the bacterial cell surface glycan recognization activity of Md-Lec. Zone of inhibition assay showed that the zone size was highest for the lectin conjugated nanoparticles. Mechanistic study revealed that Md-Lec-pCuS NPs affect the bacterial membrane integrity and produce a large volume of reactive oxygen species to kill the bacteria. The practical aspect of using this lectin-pCuS NPs complex was evaluated by treating bacteria infected Nile tilapia (Oreochromis niloticus). The bacterial load was much less in the lectin-pCus NPs complex treated fish; moreover, the fish fully recovered from the infection. It was concluded that the conjugate of antibacterial lectin and NPs is more effective than the individual components.

Humoral and skin mucosal immune parameters, intestinal immune related genes expression and antioxidant defense in rainbow trout (Oncorhynchus mykiss) fed olive (Olea europea L.) waste

A six-week feeding trial was carried out to evaluate the effects of inclusion of dietary olive waste cake (OWC, 0, 0.5, 2.5 and 5 g kg^-1 diet) on performance, antioxidant condition and immune responses of rainbow trout (Oncorhynchus mykiss) (2.5 ± 0.1 g). Supplementing diet with 2.5 and 5 g OWC kg^-1 diet significantly enhanced serum and mucosal lysozyme activity in fish. Regarding mucosal immunity, fish fed 2.5 and 5 g OWC kg^-1 diets had higher skin mucus total Ig concentrations than other groups. In relation to antioxidant status, those in 2.5 g OWC kg^-1 and the control groups exhibited the highest and the least liver superoxide dismutase and glutathione peroxidase activities, respectively. Furthermore, the activity of liver glutathione S transferase in fish fed 2.5 and 5 g OWC kg^-1 diets was higher than the other treatments. In respect to gut cytokines gene expression, our findings demonstrated dietary OWC did not influence interlukines-1β and 10 genes expression, but relative expression of IL8 gene gradually up-regulated with increasing dietary OWC level. Moreover, fish fed 0.5 g OWC kg^-1 and the control diets had the highest and the lowest gut tumor necrosis factor-α gene expression values, respectively. The relative expression of transforming growth factor-β significantly down-regulated in gut of fish fed 2.5 and 5 g OWC kg^-1 diets compared to other groups. Supplementing diet with OWC pronouncedly improved growth and feed conversion ratio in fish compared to the control. Overall, the findings of this study suggested that inclusion of 2.5 g OWC kg^-1 diet can improve growth rate, oxidative stress status, humoral and skin mucosal immune responses in O. mykiss fingerlings and it can be considered as a functional feed additive for this species.

Growth performance and hemato-immunological responses of Nile tilapia (Oreochromis niloticus) exposed to deltamethrin and fed immunobiotics

The use of feed additives in aquatic animals improves health conditions and well-being under pesticide toxicity. Thus, this study was aimed at evaluating the effect of an immunobiotic mixture (IM) on the growth performance, hemato-biochemistry, and immunity of Nile tilapia exposed to subacute deltamethrin (DMT). Fish were distributed into four groups: groups 1 and 2 were fed a control diet, while groups 3 and 4 were fed IM. Groups 2 and 4 were exposed to DMT (15 μg/L) in rearing water. The results revealed that DMT-exposed fish exhibited significantly lower final body weights, weight gain, specific growth rate, and survival rate (P < 0.05), while IM feeding resulted in improved growth performance and survival rate in fish with or without DMT toxicity. After 15 and 30 days, DMT-treated fish showed a significant increase in blood urea and bilirubin as well as hepatic enzymes (alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase) (P < 0.05), while supplementation of the IM mixture significantly lowered these levels in Nile tilapia. Blood total protein, globulin, albumin, white blood cells, red blood cells, hemoglobin, phagocytic index, and phagocytic and lysozyme activities were significantly decreased in tilapia subjected to DMT (P < 0.05), while supplementation of the IM mixture significantly increased these levels. Fish fed IM without DMT exposure showed the lowest cortisol and glucose levels, while fish exposed to DMT without IM showed the highest levels (P < 0.05) after 15 and 30 days. To conclude, IM supplementation exhibited defensive effects against DMT toxicity in Nile tilapia by improving growth performance, hematology, blood biochemistry, and immunity.