Plant protein (PP) sources are generally used in high levels in fish diets. Mostly, PP sources are deficient in taurine; hence, there is a need for its supplementation to fish fed high PP diets. ...Therefore, effects of dietary taurine were examined on growth performance, feed utilization, immunity, and antioxidant parameters of African catfish,
Clarias gariepinus
(B.). Fish (10.3 ± 0.4 g) were fed on diets (40% crude protein) containing different taurine levels of 0 (control), 10, 20, 30, or 40 g/kg diet for 12 weeks. Fish fed a taurine-free diet (the control) with high PP sources showed poor growth as compared with these fed taurine-enriched diets where taurine stimulatory effects were observed on fish growth and feed intake. Feed conversion ratio and fish survival rate were not significantly differed among different treatments. Fish fed taurine-enriched diets showed also higher levels of serum glucose, cholesterol, total protein, albumin, globulin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, urea, and creatinine over that fed the control diet. Furthermore, lysozyme and respiratory burst activities as well as superoxide dismutase and catalase activities were significantly elevated in fish fed taurine-enriched diets (
P
< 0.05) and their highest levels were observed in fish fed 30 g/kg diet. Additionally, taurine deposition in fish muscles was positively correlated with dietary taurine levels (
P
< 0.05). The present study concludes that taurine is a limiting factor for growth, immunity, and antioxidants responses of African catfish fed high PP-based diets and it should be incorporated in its diets with an optimum level of 20 g/kg diet.
Selenium (Se) is an important micronutrient that has been used in aquafeeds for the normal growth, welfare and health of aquatic animals. Through nanotechnology, Se can be converted into ...nanoparticles that are more bioavailable, utilized and absorbed by aquatic animals. However, this is still a new and emerging area of research in aquafeeds. This paper aims to review the effect of Se and Se nanoparticles (Se‐NPs) application in aquafeeds on aquatic animals. Specifically, different compounds of Se, requirement levels by different species, effects on animal growth, physiology, antioxidant capacity and immune response have been highlighted. The review shows that the application of Se in aquafeeds could improve the growth performance, physiology, antioxidant enzymes, immunity and disease resistance in aquatic animals. However, the effectiveness could be highly influenced by the source of Se, aquaculture species and administration quantity. Through nanotechnology, the utilization and absorption of Se could be improved while reducing its toxicity. Therefore, Se‐NPs present an efficient way to utilize nutrients in aquafeeds. Important gaps, however, exist in the current knowledge, particularly with regard to the response of shrimps and crustaceans to dietary supplementation of Se and Se‐NPs as most of the existing studies have focused on fish species. Also, some species of economic importance and life stages have not been investigated, which hinders the embracement of nanotechnology in aquafeeds production.
Microbial diseases cause economic loss in aquaculture on a global scale, and the use of commercial antibiotics for disease treatment produces undesirable side effects. As many medicinal herbs have ...evolved a potent defense against pathogenic bacteria, there is a growing interest in these herbs as sources for natural antibacterial agents. In this context, this study was undertaken to evaluate the effect of turmeric powder (TP), Curcuma longa, on the performance and innate immunity of common carp, Cyprinus carpio L., and its challenge against Aeromonas hydrophila infection. Fish (1.4 ± 0.06 g) were fed 0.0 (control), 1.0, 2.0, or 5.0 g TP/kg diet up to satiation twice daily for 10 wk. After the feeding trial, fish of each treatment were intraperitoneally injected by pathogenic A. hydrophila, and they were kept under observation for 10 d during which the daily mortality was recorded. The growth‐promoting effect of TP was monitored and observed where fish growth and innate immunity increased significantly as dietary TP levels increased. According to the regression curve, the most suitable TP level for optimal fish growth and health was found to be 2.0 g/kg. On the other hand, TP inclusion in the fish diet did not significantly affect fish body contents. The obtained results indicate that TP supplementation is a promising immunostimulant, which could improve fish performance and innate immunity and prevent common carp aermoniosis at a level of 2.0 g/kg diet.
Water quality encompasses the water physical, biological, and chemical parameters. It generally affects the fish growth and welfare. Thus, the success of a commercial aquaculture project depends on ...supplying the optimum water quality for prompt fish growth at the minimum cost of resources. Although the aquaculture environment is a complicated system, depending on various water quality variables, only less of them have a critical role. One of these vital parameters is dissolved oxygen (DO) level, which requires continuous oversight in aquaculture systems. In addition, the processes of natural stream refinement require suitable DO levels in order to extend for aerobic life forms. The depletion of DO concentration (called hypoxia) in pond water causes great stress on fish where DO levels that remain below 1–2 mg/L for a few hours can adversely affect fish growth resulting in fish death. Furthermore, hypoxia has substantial effects on fish physiological and immune responses, making them more susceptible to diseases. Therefore, to avoid disease outbreak in modern aquaculture production systems where fish are intensified and more crowded, increasing attention should be taken into account on DO levels.
The occurrence of pathogenic bacteria, Aeromonas hydrophila, in farm‐raised fish requires urgent attention. Continuous and indiscriminate use of antibiotics as growth promoters and disease control ...agents in aquaculture have been discouraged because of the risk of development of antibiotic‐resistant bacterial strains. There is steady interest in the use of botanicals, such as clove, Eugenia caryophyllata, buds extract (ECBE), as alternatives. Hence, the present study evaluated the effect of dietary ECBE supplementation on the growth performance, physiological, antioxidant, and immunity biomarkers of African catfish, Clarias gariepinus. Fish (11.7 ± 0.5 g) were fed diets containing 0.0 (control), 5.0, 10.0, or 15.0 g ECBE/kg diet up to apparent satiation twice daily for 12 weeks. After the feeding trial, fish from each treatment were challenged with A. hydrophila infection by intraperitoneal injection and kept under observation for 14 days to record any abnormal clinical signs and daily mortality. The results demonstrated that fish performance and feed intake were significantly enhanced with increasing ECBE levels, and its optimum level is 15 g/kg diet. Further, the dietary ECBE increased significantly the intestinal villi length/width and absorption area in a dose‐dependent manner. There are significant progressive increases in the values of red blood cells, hemoglobin, hematocrit, white blood cells, platelets, lymphocytes, and heterocytes, while monocytes, eosinophil, and basophils decreased significantly due to dietary ECBE in a dose‐dependent manner. Highest glucose, cholesterol, total protein, globulin, and albumin‐globulin ratios, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), urea, and creatinine values were found in fish fed 15 g ECBE/kg diets, while lowest values were recorded in fish fed the control diet. Despite the high AST and ALT values, no visible lesions or damage were observed in the liver cells of fish fed ECBE‐enriched diets. In addition, the inclusion of ECBE in fish diets enhanced the antioxidant and immunity capacity. Fish mortality after the bacterial challenge was higher in fish fed the control diet (82.3%) than those fed ECBE‐enriched diets. The lowest fish mortality was observed in fish fed the 15 ECBE/kg diet (4.7%) Correction added on 16 November 2018: this section has been revised for clarity..
In the present study, Indian shrimp, Penaeus indicus, were fed on diets supplemented with basil (Ocimum basilicum) oil (BO) to observe the growth performance, antioxidant and innate immune responses, ...and the resistance against Vibrio parahaemolyticus infection. The animals (5.0–5.5 g) were fed on diets supplemented with 0.0 (control), 1.0, 2.5 and 5 g BO/kg diet over 90 days. After the feeding trial, animals were intramuscularly injected by V. parahaemolyticus and observed for 96 h for mortality or any abnormal signs. Growth‐stimulating effects of dietary BO supplementation on final weight, weight gain percentage, specific growth rate and feed intake were observed. No significant differences were found in feed conversion ratio, protein efficiency ratio, protein productive value and animal survival. Feeding the animals on BO‐enriched diets did not significantly affect the chemical proximate composition of animals’ muscles. Increased values of total protein, albumin and globulin were observed in BO‐fed animals; meanwhile, aspartate and alanine aminotransferases as well as creatinine and urea levels significantly decreased in animals fed 2.5–5.0 g BO/kg diet. Activities of superoxide dismutase, catalase, glutathione peroxidase, lysozyme and phenol oxide activity significantly (p < .05) increased in the BO‐fed fish, with highest values in treatments of 2.5–5.0 g/kg diet. The dietary BO supplementation significantly (p < .05) decreased levels of malondialdehyde and nitrous oxide. After the bacterial challenge, 66.7 percent of animals in the control group were dead. The BO‐fed animals were more resistant against bacterial challenge especially at levels of 2.5–5.0 g/kg diet, which showed high relative percentage of survival (80.0–86.7 percent). In conclusion, dietary BO supplementation with levels of 2.5–5.0 g/kg diet proved beneficial effects to Indian shrimp where growth performance, antioxidant systems and innate immunity were stimulated. It also promoted the challenge of Indian shrimp against V. parahaemolyticus infection.
Immunostimulatory feed supplements have an increasingly interest in aquaculture management. Generally, an individual supplement was used in fish diets but it is expected that the use of ...multi‐supplements may show synergistic enhancements in fish performance, health, and immunity. Therefore, the present investigation was carried out to evaluate the use of dietary probiotic Lactobacillus plantarum and whey protein concentrate (WPC) in practical diets for Nile tilapia, Oreochromis niloticus. Hence, probiotic L. plantarum, WPC and their mixture were incorporated into a basal fish diet (300 g/kg crude protein) as follows: T1 = a basal control diet, T2 = a basal diet containing L. plantarum, T3 = a basal diet containing 1.0 g WCP/kg diet and T4, T5 or T6 = basal diets containing probiotic L. plantarum + 1.0, 2.0 or 3.0 g WCP/kg diet, respectively. Fish (15.2 ± 0.6 g) were fed on one of the tested diets up to apparent satiation twice a day for 60 days. After that, fish were intraperitoneally injected with pathogenic bacteria Aeromonas sobria and fish mortality was observed for 10 days postchallenge. Fish growth and feed intake were significantly improved by dietary probiotic L. plantarum (T2) and/or WPC (T3) over the control group (T1), and highest fish performance was observed in T5–T6 fish groups. Similarly, highest values of haematocrit, glucose, total proteins, albumin, and globulin were significantly observed in T5–T6 fish groups. Likewise, fish fed dietary probiotic L. plantarum (T2), WPC (T3), and their mixture (T4–T6) showed antioxidants and immune‐stimulating activities better than the control group. Fish fed the control diet were more susceptible to A. sobria infection showing highest fish mortality (75.0%). Meanwhile, dietary probiotic L. plantarum (T2), WPC (T3), and their mixture (T4–T6) enhanced significantly the fish resistance to A. sobria infection resulting in maximum values of relative percent of fish survival (73.3%–80.0%) in T5–T6 groups. The present investigation recommended the use of probiotic L. plantarum with 2.0 g WPC/kg diet to improve the growth, antioxidant, immunity responses and tolerance of Nile tilapia to A. sobria infection.
The microbial phytase, derived from Buttiauxella gaviniae, Yersinia mollarettiv and Hafnia spp., is proven to be safe for avian and porcine feeding and promotes their overall growth performance. ...Here, we have evaluated microbial phytase's effects on the growth, bone mineral content, antioxidant status, immune responses and the resistance of African catfish (Clarias gariepinus) fed with high soybean meal‐based diets against Aeromonas hydrophila infection. Five isonitrogenous diets (40% protein) were supplemented with different levels of microbial phytase ranging from 0 as a control to 250, 500, 750 and 1000 FTU/kg diet. African catfish (n = 300; 8.5 ± 0.3 g) were allocated in 15 50‐L tanks (in triplicates) and were fed on the prepared tested diets for 12 weeks. After the end of the feeding period of 12 weeks, 10 fish from each replicate was intraperitoneally infected with A. hydrophila (0.5 × 105 CFU/ml) and monitored for 14 days. Dietary phytase levels linearly and quadratically improved the growth performance of African catfish and stimulated feed intake. Bone levels of calcium, phosphorus, magnesium and zinc were also positively modulated in phytase‐fed fish, especially at 750–1000 FTU/kg diet. Similarly, counts of red and white blood cells as well as haemoglobin, packed cells volume, platelets, lymphocytes and heterocytes were significantly modulated in all fish fed with phytase‐supplemented diets. Higher levels of serum total protein, albumin and globulin were also observed in fish fed with a 750–1000 FTU/kg diet of phytase. Conversely, aspartate and alanine aminotransferase activities were lower in fish fed with a 750–1000 FTU/kg diet of phytase, compared to those fed the control diet. Moreover, antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), reduced glutathione levels and immune responses (lysozyme, respiratory burst, protease and alkaline phosphatase activities) biomarkers were linearly and quadratically elevated, while malondialdehyde values were linearly and quadratically decreased in fish groups fed with phytase‐based diets. After administering A. hydrophila, 60.0% of the fish fed the control diet perished, while no mortalities were observed in fish fed with 750–1000 FTU/kg diets. Taken together, the current study reveals that dietary phytase could improve the growth performance, blood profile, bone mineralization, antioxidant activities, immunity and overall protection of African catfish against A. hydrophila infection. Dietary phytase may be efficiently used in the feeding of African catfish to enhance their overall performance and mitigate health conditions with optimum level of 900 FTU/kg diet.
The dietary effects of the green microalga Tetraselmis suecica (TS) on the growth, digestive enzymes, immune and antioxidant responses, genes expression, and disease resistance of Nile tilapia ...(Oreochromis niloticus) fingerlings were investigated. This microalga was mixed with the diet' ingredients at doses of 0.0 (the control), 5, 10, 15, and 20 g/kg diet and then fed to fish daily for 84 days. After the feeding trial, fish were experimentally challenged with Aeromonas sobria, infection and fish mortalities were recorded for another 10 days. Dietary TS significantly (p < 0.05) enhanced growth, digestive enzymes activities, and blood proteins, particularly at the level of 15 g/kg diet. Feeding the fish on 15 TS/kg feed exhibited highest mRNA expressions of GH and IGF‐1 genes as well as SOD, CAT, and GPx genes compared to other TS groups. Moreover, highest levels of hepatic antioxidant and immune indices were found in the treatment of 15 g TS/kg feed. Significant downregulation of IL‐1β and IL‐8 genes expression and significant upregulation of IL‐10 gene expression were observed in TS‐fed fish, principally in fish groups fed on 15−20 g TS/kg feed. Conversely, hepatic malondialdehyde levels, blood glucose, and the activities of transaminases (ALT and AST) were significantly (p < 0.05) decreased in fish fed with 15−20 g TS/kg diet. Serum bactericidal activity against A. sobria was significantly higher in TS‐fed fish groups, and its highest levels were found in treatments of 15−20 g/kg diet. Of interest, the survival rates of fish groups fed diets with 10−20 g TS/kg feed were higher after the challenge with A. sobria infection than the control group. Accordingly, we can conclude that supplementing fish diets with a 15 g TS/kg diet enhanced the growth, antioxidant and immune activities, and resistance of Nile tilapia fingerlings to possible A. sobria infection.
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