An understanding of how to nurture and/or modulate the different components of the immune system is crucial for the prevention and control of diseases in animal husbandry. It is well established that ...proper nutrition is essential for maintenance of normal growth and health of all animals including aquatic species. As such, nutritious diets and appropriate feeding regimes play critical roles in intensive aquaculture. In recent years, heightened attention has been given to the development of nutritional strategies that positively influence immunity and disease resistance of cultured organisms to reduce disease-related economic losses. The availability of specific nutrients to immune cells plays a key role on how well those cells perform against a foreign invader. In this sense, research with several fish species has established that not only immunocompetence can be compromised by deficiencies of various nutrients, but that dietary supplementation of some nutrients in excess of minimum requirement levels for optimal growth has been shown to significantly enhance immune responses and disease resistance. For instance, findings from recent studies indicate an important role of key amino acids and their derivatives, like arginine and glutamine, or vitamins, such as vitamin C and E, in modulating immune responses such as increasing phagocytosis and pathogen killing capacity, as well as increasing antibody production and immunological memory. In addition, administration of non-nutritive compounds in the diet has become recognized as a viable means of enhancing immunocompetence of various aquatic species, mainly by the provision of cellular fractions such as β-glucans, complex oligosaccharides (mannanoligosaccharides, fructooligosaccharides or sulfated polysaccharides) or yeast and algae extracts. These compounds may act like Pathogen Associated Molecular Pattern (PAMP) molecules, interacting with the innate immune system through their Pattern Recognition Receptors (PRRs) and increasing their capability for detecting and recognizing potential pathogens and readily triggering immune responses. This article will review the broad range of dietary constituents which have been shown to affect immunocompetence and health of aquatic species and how they may influence components of the immune system. Further advancements in nutritional modulation of the immune response hold promise as an effective and relatively inexpensive alternative in combating diseases in aquaculture.
•Disease resistance of fish can be influenced by nutritional strategies.•Specific nutrients in excess of minimum requirement enhance immune response and memory.•Provision of non-nutritive compounds increases non-specific protection.•Dietary constituents that affect immunocompetence and health of aquatic species are reviewed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A current priority in the aquaculture industry is the replacement of fishmeal with alternative feedstuffs, including plant-based protein ingredients, to ensure its sustainability. However, most ...plant-based feedstuffs have a wide variety of anti-nutritional factors, which may impair nutrient utilization, interfering with fish performance and health. The use of exogenous enzymes as feed additives to improve nutrient digestibility of plant-based feedstuffs has been researched extensively in poultry and swine. In aquaculture, the use of phytase to improve phosphorus utilization has emerged quite readily. However, the use of carbohydrase enzymes has not been as nearly as common in aquatic species, despite their promising effects in improving nutrient digestibility by hydrolyzing non-starch polysaccharides present in plant feedstuffs. Based on the information gathered in this review, supplementation of exogenous carbohydrases to plant-based fish diets should improve nutrient digestibility and reduce nutrient excretion. On the other hand, the effects of exogenous carbohydrases on fish performance are still unclear due to the difficulty in cross-study comparisons. Overall, based on the information gathered in this review, it is clear that research on exogenous carbohydrase supplementation in aquaculture nutrition is not extensive. According to promising results and opportunities found in other non-ruminant animals, and favorable effects found in aquaculture species studied to date, it may be significant to increase research on this subject because it could be a useful tool to improve and sustain commercial aquaculture.
•Exogenous enzymes may improve nutrient digestibility of plant-based fish diets.•Carbohydrases hydrolyze non-starch polysaccharides present in plant feedstuffs.•Stability and performance of exogenous enzymes may still improve for them to be more readily incorporated in fish diets.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This study aimed to elucidate the effects of selenium-loaded chitosan nanoparticles used as a dietary supplement on Nile tilapia (Oreochromis niloticus) antioxidant and growth responses. First, ...chitosan-based nanoparticles containing selenium (Se) were synthesized using the ionotropic gelation method and their physicochemical characteristics, controlled release profile, and antioxidant activity properties were investigated. Thereafter, the effects on glutathione peroxidase and antioxidant activities (by radical scavenging activity), growth, and whole-body composition of Nile tilapia were evaluated when they were fed with Se-loaded chitosan nanoparticles and compared with other selenium dietary supplements. Se-loaded chitosan nanoparticles showed high entrapment efficiency (87%), spherical shape, smooth surface, and broad size distribution. The controlled release of Se consisted of an initial burst followed by a gradual release over 48 h. Se-loaded nanoparticles presented significantly higher antioxidant activity compared to free Se. A 60-day feeding trial was conducted to compare the effects of supplementing different dietary Se sources, including selenomethionine (as organic source), sodium selenite (as inorganic source), and Se-loaded chitosan nanoparticles (Se-Nano and Se-Nano x1.5) on antioxidant and growth responses of Nile tilapia. A basal diet without Se supplementation was used as the control. The dietary supplementations with different Se sources (free and encapsulated selenium) lead to significant improvements in final weight and feed efficiency of Nile tilapia fingerlings. However, dietary treatments did not affect whole-body protein and lipid content. Diets containing Se-Nano and Se-Nano x1.5 were more effective than sodium selenite and selenomethionine in preventing oxidative stress and improving antioxidant activity in Nile tilapia. Overall, Se-loaded nanoparticles presented a great potential as an efficient source for delivering dietary Se to Nile tilapia, directly affecting the growth performance, feed efficiency, oxidative stress, and antioxidant activity of this species.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dietary nucleotides have been shown to benefit many physiological and nutritional functions in higher vertebrates and fish. Therefore, a 6-week feeding trial was conducted to evaluate the effects of ...graded levels of a commercial nucleotide product on growth performance, immune responses and intestinal morphology of juvenile red drum (initial average weight of 7.1
g). The basal diet was formulated to contain 40% protein, 10% lipid and a digestible energy level of 3.5
kcal
g
−1. Two levels of nucleotide (Ascogen P
®, 0.5% and 1% of diet) were added to the basal diet with menhaden fishmeal and menhaden oil adjusted to provide isonitrogenous and isolipidic diets. Nucleotide supplementation tended to improve weight gain and survival of red drum, but not at a significant level. Neutrophil oxidative radical anion production and serum lysozyme activity tended to be higher for fish fed diets supplemented with nucleotide, while extracellular superoxide anion production of head kidney macrophages from fish fed diets with 1% nucleotide was significantly (
P
<
0.05) increased, although no significant differences were observed between fish fed 0.5% nucleotide diet and the basal diet.
Nucleotide supplementation significantly (
P
<
0.05) increased fold height in the proximal intestine, and enterocyte height in the pyloric caeca, proximal and distal enteric sections. A significantly (
P
<
0.05) higher microvilli height was observed in all evaluated enteric sections of fish fed with diets supplemented with nucleotides. It is therefore possible to use dietary nucleotides supplementation to significantly enhance the intestinal structure of red drum. Likewise, nucleotides in the diet may improve some components of the non-specific immune response of this sciaenid fish.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Continued growth and intensification of aquaculture production depends upon the development of sustainable protein sources to replace fish meal in aquafeeds. This document reviews various plant ...feedstuffs, which currently are or potentially may be incorporated into aquafeeds to support the sustainable production of various fish species in aquaculture. The plant feedstuffs considered include oilseeds, legumes and cereal grains, which traditionally have been used as protein or energy concentrates as well as novel products developed through various processing technologies. The nutritional composition of these various feedstuffs are considered along with the presence of any bioactive compounds that may positively or negatively affect the target organism. Lipid composition of these feedstuffs is not specifically considered although it is recognized that incorporating lipid supplements in aquafeeds to achieve proper fatty acid profiles to meet the metabolic requirements of fish and maximize human health benefits are important aspects. Specific strategies and techniques to optimize the nutritional composition of plant feedstuffs and limit potentially adverse effects of bioactive compounds are also described. Such information will provide a foundation for developing strategic research plans for increasing the use of plant feedstuffs in aquaculture to reduce dependence of animal feedstuffs and thereby enhance the sustainability of aquaculture.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The effects of four prebiotics (fructo-oligosaccharide, Bio-MOS®, transgalacto-oligosaccharide and GroBiotic®-A) on digestive enzymes and intestinal morphology were studied in juvenile hybrid striped ...bass (Morone chrysops×M. saxatilis) and red drum (Sciaenops ocellatus) using two separate 8-week feeding trials. Red drum were fed experimental diets with the four prebiotics each individually supplemented at 1 % and hybrid striped bass were fed diets supplemented with GroBiotic®-A at 1 and 2 %. Both trials were conducted with each diet fed to apparent satiation twice per d to three replicate groups of fifteen juvenile fish. For histomorphological analysis, gastrointestinal tract (GIT) samples from three randomly selected fish per tank were taken at 4 and 8 weeks for hybrid striped bass and at 8 weeks for red drum. For both trials, GIT samples from two randomly selected fish per tank were taken at 4 and 8 weeks and analysed for pepsin, trypsin, chymotrypsin, aminopeptidase, α-amylase, lipase, and both acid and alkaline phosphatase activities. The results of the histological evaluation indicated that the inclusion of prebiotics was adequate to elicit structural changes in the GIT of both species. On the other hand, no significant changes in the enzyme activities were detected at week 8 in both species. However, there was a transient effect of Bio-MOS® supplementation on the activities of aminopeptidase, α-amylase and alkaline phosphatase at week 4 in red drum only. Thus, previously observed improvements in nutrient digestibility by these fish in response to prebiotic supplementation appear to be mostly related to changes in GIT structure as opposed to the enhancement of digestive enzyme activity.
Various studies with fish species indicate that dietary arginine (Arg) and glutamine (Gln) supplementation may support an enhanced performance beyond simply improving weight gain. Therefore, a ...feeding trial was conducted to determine the effects of dietary Arg or Gln on growth performance, immune responses and intestinal morphology of juvenile hybrid striped bass, Morone chrysops×Morone saxatilis (4.1±0.02g, initial average weight). The basal diet was formulated from menhaden fishmeal and solvent-extracted soybean meal to contain 45% crude protein and 10% lipid. Arginine and Gln were singularly added to the basal diet at either 1% or 2% or both amino acids were added in combination at 1% to formulate experimental diets with adjustments in glycine to maintain all diets iso-nitrogenous. Fish were fed the experimental diets for a period of 8weeks, at the end of which final weight, specific growth rate and feed efficiency were significantly (P<0.05) higher in fish fed diets supplemented with Arg at either 1 or 2%, Gln at 1%, Arg and Gln both at 1%, but not in those fed the diet supplemented with Gln at 2%.
Arginine and/or Gln supplementation tended to improve neutrophil oxidative radical production, but not significantly (P>0.05). However, significantly higher serum lysozyme activity was observed in fish fed the diet supplemented with Arg at either 1 or 2% and Gln at 1%. Intracellular superoxide anion production by hybrid striped bass macrophages also tended to increase, while extracellular superoxide anion production was significantly improved by supplementation of Arg at 1% and Gln at either 1 or 2% of diet.
Morphometric analyses demonstrated positive effects of both dietary Arg and Gln on histo-morphological measurements in different portions of the gastrointestinal tract of hybrid striped bass. The 1% Arg diet resulted in the greatest increases in size of the chosen enteric structures, but the other four experimental diets also significantly improved the scores for various intestinal portions compared to fish fed the basal diet.
Results from the present experiment demonstrate the importance of dietary supplementation of both Arg and Gln in improving growth performance, eliciting positive changes to several components of the innate immune system, and also benefiting the intestinal functionality of hybrid striped bass.
► We test Arg/Gln supplementation to improve immune response in hybrid striped bass. ► Several indicators of this response were improved upon supplementation. ► Other parameters displayed positive trends with Arg and/or Gln dietary enrichment. ► Intestinal structures and likely nutrient absorption were also positively affected.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In aquaculture species, organic acids and their salts have been shown to trigger beneficial effects on mineral absorption, nutrient digestibility and growth performance by reducing the pH in the ...digestive tract through H+ ion deposition. Therefore, the aim of this study was to determine if calcium lactate (CaLac), citric acid (CA) and potassium diformate (KDF) can improve growth performance of juvenile red drum (Sciaenops ocellatus) and if improved performance is in part due to an increase in digestive enzyme activities. A basal diet was formulated to contain 40% crude protein and six experimental diets were prepared by supplementing the basal diet with 1.5% or 3.0% CaLac, 0.75% or 1.5% CA and 0.75% or 1.5% KDF. One hundred eighty juvenile red drum were stocked in 110-L glass aquaria (20 fish/aquarium), and diets were fed to fish in triplicate aquaria at a rate approaching apparent satiation, twice daily, for 8weeks in two separate trials. At the end of each feeding trial, growth performance indicators were obtained and four fish per aquarium were euthanized to measure pH of the digestive tract contents as well as to evaluate the digestive enzyme activities. The pH of the experimental diets was lowered by the addition of 0.75% CA (pH5.63), 1.5% CA (pH5.36) and 1.5% KDF (pH5.79) when compared with the basal diet (pH6.15). Moreover, the pH values of the stomach contents were correlated with the pH of the experimental diets. Additionally, based on the weight gain results, it seems that organic acids at a 1.5% dose can improve growth performance in juvenile red drum, although only the weight gain in the 1.5% CA treatment (1547%) was significantly higher than the basal treatment (1357%). This enhanced performance may be in part due to an increment in the activity of digestive enzymes, because pepsin activity, pancreatic enzyme activities (trypsin and lipase) and intestinal enzyme activities (leucin-aminopeptidase and phosphatases) were higher with the inclusion of organic acids in the diet.
•The effects of a dietary inclusion of organic acids in juvenile red drum performance were evaluated.•1.5% citric acid inclusion improved growth performance of red drum.•Organic acids increased the activity of digestive enzymes in red drum.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A dietary requirement for the sulfonic acid taurine has been documented in many marine species. However, it has not been well studied in hybrid fish with freshwater and marine genes, such as the ...hybrid striped bass (Morone chrysops x M. saxatilis). Therefore, an 8-week feeding trial was conducted to evaluate the effects of various levels of dietary taurine on growth performance, health, and body composition of juvenile hybrid striped bass. Four diets were formulated from practical ingredients and supplemented with DL-methionine at 0.54% of dry weight to meet the hybrid striped bass' established total sulfur amino acid requirement of 1.0% of dry diet, and taurine was supplemented incrementally at 0, 0.5, 1, and 2% of dry weight. Two additional diets were prepared without DL-methionine supplementation to be marginally deficient in methionine (0.49% by weight) and either supplemented with or without taurine at 1% dry weight to evaluate the potential interactions between methionine and taurine. Diets containing increment levels of taurine were determined to show no significant (P > .05) differences in terms of weight gain, feed efficiency (FE), whole-body composition, hepatosomatic index (HSI), intraperitoneal fat ratio (IPF ratio), or muscle yield. However, hybrid striped bass fed the methionine-deficient diets had significantly (P < .05) reduced percentage weight gain and FE as well as reduced muscle yield and HSI compared to fish fed the methionine-supplemented diets. Interestingly, taurine inclusion at 1% in the diet containing 0.49% methionine increased weight gain and feed efficiency of fish compared to those fed the diet without supplemental taurine or methionine. These results indicated that growth performance and body composition of hybrid striped bass did not respond to taurine supplementation when dietary methionine was adequate but did respond when dietary methionine was limiting.
•Taurine supplementation up to 2% of dry diet increased plasma taurine concentrations in hybrid striped bass.•Taurine supplementation up to 2% of dry weight in a methionine-sufficient diet did not significantly enhance growth performance.•Taurine supplementation in a methionine-deficient diet increased growth performance similar to a methionine-sufficient diet indicating sparing of the sulfur amino acid requirement.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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