Figure 4 - available from: Fish Physiology and Biochemistry
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Simplified diagram of purine nucleotide catabolism in fish, resulting in production of hydrogen peroxide (H2O2) that can be: (1) reduced to H2O by glutathione peroxidase given adequate glutathione SH:SS ratio maintained by the pentose phosphate pathway, or (2) used to oxidise haemoglobin to methaemoglobin molecules that link to form Heinz bodies, modified from Sanchez-Muniz et al. (1982) and Berg et al. (2015)
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Yeast is a potential alternative to fish meal in diets for farmed fish, yet replacing more than 50 % of fish meal results in reduced fish growth. In a 4-week experiment, 15 rainbow trout (Oncorhynchus mykiss) were cannulated and fed three diets each week: 30 % fish meal as a control (FM); 60 % replacement of fish meal protein, on a digestible basis...
Citations
... However, several countries have strict legislation on the use of feed additives (Baets et al., 2009). Thus, food additives based on the yeast Saccharomyces cerevisiae or its co-products were tried in order to stimulate growth and act as an immunomodulator in Labeo rohita (Twary and Patra, 2011), Huso huso (Hoseinifar (Abdel-Tawwab et al., 2008;Amin et al., 2015), Piaractus mesopotamicus (Biller-Takahashi et al., 2014;Hisano et al., 2018), Rutilus frisii (Rufchaie and Hoseinifar, 2014), Solea senegalensis (Batista et al., 2016), Oncorhynchus mykiss (Huyben et al., 2017), Brycon amazonicus (Montoya et al., 2018) and Arapaima gigas (Dias et al., 2019). Much of this research has expressed not only the importance of the effects of immunostimulants, but also improvements in performance, survival and feed conversion (Twary and Patra 2011; Batista ...
... One of the main challenges of fish farming is to increase weight gain, survival rates and fish growth. The yeast Sacharomyces cerevisiae has been recommended as a dietary supplement due to its high protein content, immunostimulating effects and improvements in the performance of farmed fish (Huyben et al., 2017;Dias et al., 2019). In the present study, A. gigas received different treatments with prebiotics derived from the yeast S. cerevisiae. ...
... In fish, the ingestion of lipopolysaccharide-based immunostimulates from the yeast cell wall has advantages and is a useful method of exposure in large-scale fish farming. And then it was evaluated in some research (Hoseinifar et al., 2011;Tewary and Patra, 2011;Rufchaie and Hoseinifar, 2014;Amin et al. 2015;Mannopo et al., 2015;Huyben et al. 2017;Hoshino et al. 2017 The evolution of fish farming depends on the intensification of production systems, so factors such as water quality, stocking density, food and health are relevant to the system's productivity (Aubin et al., 2017). In intensive fish farms, the nutrition and health of aquatic organisms are essential, as the opportunistic bacteria found in the environment can modify the microbiotaof fish and cause outbreaks of mortality in production, as occurred in the present study. ...
The study aimed to evaluate the effect on zootechnical performance and survival of pirarucu juveniles (Arapaima gigas) submitted to prebiotic supplementation in their diet. Were 120 juveniles of A. gigas acquired, acclimated in water-boxes with continuous aeration and water flow, and fed ad libitum four times a day, with a diet containing 55% crude protein. The 25.5 ± 3.5 g fish were distributed in 12 water-boxes of 500L (3 water-boxes/treatment and 10 fish/water-box). Juveniles were subjected to control (without prebiotics) and also subjected to three treatments A, B and C. The parasites found were observed under optical and scanning electron microscopy (SEM). Fish were distributed in completely randomized design water-boxes. The data obtained were evaluated by the Shapiro-Wilk and Bartlett’s tests (α=0.05). Then, they were submitted to ANOVA, and contrasted by the Tukey’s test (α=0.05). While the treatments were contrasted with each other by Dunn's test (α=0.05). The water quality parameters were kept adequate for A. gigas cultivation. In treatments, zootechnical performance and survival rate differed from each other, and were better than the control (p<0.05). Treatment A expressed the highest final weight 77.32 ± 10.23g (p<0.05), and the control had the lowest final weight 20.08 ± 6.64g. The average weight gain was different between treatments (p<0.05), which presented better results than the control (p<0.05). Treatments A and C expressed the highest mean weight gain 49.90 ± 8.95 and 54.17 ± 4.12 g (p<0.05), respectively. The final biomass was different between treatments, which showed better results than the control group (p<0.05). Survival rate was not different between treatments (p>0.05). However, the control presented the lowest rate of 13.33%, due to trichodinid infestation. Supplemented prebiotics were beneficial for weight gain, final biomass, apparent feed conversion and survival of pirarucu juveniles.
... In the current study, fish were left undisturbed for 48 h, which resulted in low basal cortisol levels. This is consistent with earlier studies where cortisol restored to basal levels within 24-48 h post stress in salmonids Huyben et al., 2017;Pickering & Pottinger, 1989;Procarione et al., 1999;Yousaf et al., 2022). Furthermore, basal cortisol levels in undisturbed adult Atlantic salmon have been reported in the range of 4.23-59.49 ...
A swim tunnel is to fish as a treadmill is to humans, and is a device used for indirect measuring of the metabolic rate. This study aims to explore the fish stress (if any) during the critical swimming test routines (fish handling, confinement, and swimming) using heart rate (fH, heartbeat per minute) bio‐loggers in farmed Atlantic salmon (Salmo salar L.). In addition, the recovery dynamics of exercised fish using fH were explored for 48 h post swim tests. Continuous fH data were acquired following the surgical implantation and throughout the trials, such as during fish handling, swim tests (critical swimming speed, Ucrit), and 48 h post swim tests. After 3 weeks of surgical recovery, fH stabilized at 46.20 ± 1.26 beats min⁻¹, equalizing a ~38% reduction in fH recorded post‐surgical tachycardia (74.13 ± 1.44 beats min⁻¹). Interestingly, fH was elevated by ~200% compared to baseline levels not only due to the Ucrit (92.04 ± 0.23 beats min⁻¹) but also due to fish handling and confinement in the swim tunnel, which was 66% above the baseline levels (77.48 ± 0.34 beats min⁻¹), suggesting fish stress. Moreover, significantly higher plasma cortisol levels (199.56 ± 77.17 ng mL⁻¹) corresponding to a ~300% increase compared to baseline levels (47.92 ± 27.70 ng mL⁻¹) were identified after Ucrit, predicting post‐swim test stress (physiological exhaustion). These findings reinforce the importance of fish acclimation in the swim tunnel prior to the swimming tests. However, fH dropped over the course of the 48‐h post‐swim test, but remained comparatively higher than the basal levels, suggesting fish should be given at least 48 h to recover from handling stress for better fish welfare. This study further explored the influence of fish tagging on Ucrit, which resulted in reduced swimming capabilities of tagged fish (1.95 ± 0.37 body lengths s⁻¹) compared to untagged fish (2.54 ± 0.42 body length s⁻¹), although this was not significant (p = 0.06), and therefore future tagging studies are warranted.
... In the present study, heat-treating C. sake resulted in a decrease in Hb and Hct coinciding with an increase in plasma potassium compared to the untreated yeast, which suggests hemolysis (Santos and Hall, 1990). The high content of purine nucleotides of yeast may lead to the production of hydrogen peroxide that can damage red blood cells and yeast inclusion has been shown to induce hemolytic anemia in rainbow trout (Bontemps et al., 1986;Huyben et al., 2017). However, the nucleotide content was likely similar in both heat-treated and untreated yeast. ...
... But dietary 30 g/kg YC addition increased the MDA content and decreased the activities of SOD and T-AOC significantly in liver of P. ussuriensis compared with dietary 20 g/kg YC addition. As we know, yeasts contain higher levels of nucleic acids and indigestible polysaccharides [25], but too high levels of nucleic acids and polysaccharides cannot be safely metabolized in fish to generate harmful hydroxyl radicals, which can destroy antioxidant system and contribute to oxidative stress [41,42]. The results in the present study manifested that the proper YC supplementation (20 g/kg) in diet would enhance the antioxidase activities, thereby inhibiting the activity of oxygen free radicals and preventing oxidative damage; however, excessive YC addition may lead to an adverse impact for antioxidant capacity. ...
An 8-week feeding trial was conducted to evaluate the effects of dietary yeast culture (YC) supplementation on growth performance, antioxidant activity, nonspecific immunity, and disease resistance of Pseudobagrus ussuriensis (average initial weight 6.01 ± 0.01 g ). Four isonitrogenous and isolipidic diets were formulated to contain 0 (Y0), 10 (Y1), 20 (Y2), and 30 (Y3) g/kg YC, respectively. After the feeding experiment, the challenge test of injecting Aeromonas hydrophila was executed. Results showed that appropriate YC supplementation level in the diet could improve growth performance, digestive enzyme activities, nonspecific immunity capacity, antioxidant capacity, and disease resistance of P. ussuriensis. And the highest weight gain, feed intake, specific growth rate, and IGF-1 gene expression level were observed in fish fed the Y2 diet. The activities of protease and amylase in intestine in fish fed the Y2 diet were enhanced compared with that in fish fed the Y0 diet significantly ( P < 0.05 ). Simultaneously, fish fed the Y2 diet had significantly higher serum lysozyme activity and significantly lower serum alanine amino transferase activity ( P < 0.05 ). Dietary 20 g/kg YC supplementation increased the activity of catalase and total antioxidant capacity in liver and reduced malondialdehyde content in the liver and intestine of P. ussuriensis significantly ( P < 0.05 ). Fish fed the Y2 diet had the highest disease resistance under the condition of A. hydrophila challenge ( P < 0.05 ). The quadratic regression analysis based on weight gain against dietary YC levels indicated that the appropriate dietary YC supplementation level is 13.4 g/kg diet.
... These results argue against the long-term use of bacterial meals as a protein source for At the end of the feeding trial, HY-fed fish showed a decrease in mean Ht (25.2 ± 5.1%) compared to the control group (29.3 ± 5.6%, p = 0.005), suggesting the occurrence of mild hemolytic anemia; fish fed with HY-diet grew faster than the others under normal rearing conditions, but they might be susceptible to hypoxia. Similarly, hemolytic anemia was observed in rainbow trout fed with a diet in which 60% of the fishmeal was replaced by yeast meal (Huyben et al., 2017). In general, yeast contains a high level of nucleic acids, mainly RNAs, and catabolism of these dietary nucleic acids may cause a high concentration of plasma uric acids in fish; these might have an effect on protein, fat, carbohydrate, and uracil metabolism (Agboola et al., 2021). ...
... In general, yeast contains a high level of nucleic acids, mainly RNAs, and catabolism of these dietary nucleic acids may cause a high concentration of plasma uric acids in fish; these might have an effect on protein, fat, carbohydrate, and uracil metabolism (Agboola et al., 2021). Although fish can catabolize plasma uric acids, the process can generate hydrogen peroxide, a reactive oxygen species that may damage erythrocytes and cell membranes if antioxidant levels are insufficient (Huyben et al., 2017;Sánchez-Muniz et al., 1982). In our liver transcriptomic analysis (KEGG-GSEA), we found that expression of genes related to "Peroxisome", "Metabolism of xenobiotics by cytochrome P450", "Pentose and glucuronate interconversions", and "Purine metabolism" were upregulated in the HY-fed group compared to the control group (adjusted p = 0.008, 0.031, 0.031, and 0.033, respectively). ...
The rising price of fishmeal and the need for sustainable use of fishery resources have encouraged efforts by the aquaculture industry to identify alternative protein sources including plants and single cell organisms. This is particularly the case for the tiger pufferfish, Takifugu rubripes, which is fed a high level of fishmeal as the protein source. In this study, we compared four possible replacement diets: in three diets, fishmeal was reduced from 77% to 47% and replaced mainly by plant (PP), bacterial (BAC), or yeast (LY)-derived ingredients; in the fourth, reduced to 20% and replaced mainly by yeast (HY). Growth performance, blood chemistry, transcriptomic responses in the liver, and resistance to the parasite Heterobothrium okamotoi were compared in 360 cultured tiger pufferfish (9.8 months old at the start of the experiment). After a 3-month feeding trial, the HY-fed fish showed increased standard lengths (p = 0.015) and body weights (p = 0.004) compared to control fish fed the standard FM (77% fishmeal) diet. At the end of the feeding trial, FM-fed fish had a mean hematocrit (Ht) of 29.3 ± 5.6%; HY-fed fish had the lowest mean Ht of 25.2 ± 5.1% (p = 0.005). Mean total cholesterol levels in BAC-, LY- and HY-fed fish were lower than in control fish (p = 0.008, 0.004, and 0.024, respectively). In contrast, no significant difference was found for triglyceride, total protein, and glucose levels among the groups. Subsequently, 150 individuals were subjected to artificial infection with H. okamotoi; no significant differences were found for mean parasite counts and Ht values between fish fed the experimental diets and the control fish. Analysis of gene expression in the liver showed that the gene hmgcra was significantly up-regulated (based on a log2 fold change threshold) in HY-fed fish compared to FM-fed fish. Overall, the analyses indicate that a low fishmeal diet in which 71% of fishmeal is replaced mainly by yeast meal (i.e., containing 40% of yeast meal in total mass) may be a suitable replacement for the commercial FM diet as it promotes growth but does not induce severe deleterious effects.
... Some of the ingredients with stress buffering functional properties are great sources of alternative proteins (e.g., microalgae and yeasts); however, the practiced inclusion rates are very low and irrelevant, in terms of protein replacement. Studies have reported the effects of yeasts, as an alternative protein source (Table 3), on acute thermal stress [185,186], hypoxia [185], air exposure [187], handling by net chasing [188], and confinement [189], as well as how the yeast inclusion mitigates stress effects, though the results are not always in agreement. Juvenile Nile tilapia (21 g) that were fed diets with up to 7% yeast (S. cerevisiae) for 84 days had better growth performance and higher survival to acute heat stress, regardless of the inclusion rate [185]. ...
... However, it is evident that responses are species-, ingredient-, and dosage-specific and there is no "one fits all" solution, supporting the need for further research in precision nutrition to nutritionally target fish specific needs. ↔ FAA levels (after stress) ↑ Met; SAR (before stress) [189] ↔ Without differing from control; ↓ significantly lower than the control; ↑ significantly higher than the control; AC50 = The effect of insect meal in the stress response has been largely overlooked. Despite the intensification of studies regarding the utilization of this alternative protein, only few studies have addressed a possible effect on the stress response (and not in a direct manner). ...
Aquaculture has been challenged to find alternative ingredients to develop innovative feed formulations that foster a sustainable future growth. Given the most recent trends in fish feed formulation on the use of alternative protein sources to decrease the dependency of fishmeal, it is fundamental to evaluate the implications of this new paradigm for fish health and welfare. This work intends to comprehensively review the impacts of alternative and novel dietary protein sources on fish gut microbiota and health, stress and immune responses, disease resistance, and antioxidant capacity. The research results indicate that alternative protein sources, such as terrestrial plant proteins, rendered animal by-products, insect meals, micro- and macroalgae, and single cell proteins (e.g., yeasts), may negatively impact gut microbiota and health, thus affecting immune and stress responses. Nevertheless, some of the novel protein sources, such as insects and algae meals, have functional properties and may exert an immunostimulatory activity. Further research on the effects of novel protein sources, beyond growth, is clearly needed. The information gathered here is of utmost importance, in order to develop innovative diets that guarantee the production of healthy fish with high quality standards and optimised welfare conditions, thus contributing to a sustainable growth of the aquaculture industry.
... A recent study showed that tagging did not affect chronic stress physiological parameters such cortisol, glucose and lactate in sea bass and sea bream (Alfonso et al., 2020). In salmonids, plasma cortisol levels took 24-48 h to re-attain resting pre-stress levels after the stress applied Huyben et al., 2017;Pickering and Pottinger, 1989;Procarione et al., 1999). In terms of carbohydrate metabolism, fish blood glucose and lactate levels elevate upon stress (Hontela et al., 1996;Santos and Pacheco, 1996) whereas in present study lactate levels significantly elevated after stress in crowding (test 1) and grading (test 2) stressors. ...
Atlantic salmon are one of most studied cultured species, still continuous fish welfare monitoring is a challenge during commercial farming operations. Although, mortality is the terminal indicator of fish welfare, but without further explanation, this parameter is of limited use. Fish welfare on-site can be monitored by using implantable DST milli-HRT bio-loggers that record heart rate, electrocardiography and temperature. These heart rate loggers gave us the opportunity to monitor fish welfare under common farm handlings in free-swimming farmed Atlantic salmon (~1 kg). Three different stress tests such as crowding (test 1), grading (test 2) & vaccination (test 3) were performed on three separate fish groups three weeks post-surgery. Heart rate and biochemical parameters (blood plasma and mucous) including cortisol were measured and compared in pre-stressed (T0), stressed (T1) and post-stressed (T48) fish. A modified loggers anchoring technique was used where two separate thin sutures were threaded at front hole of the logger and knot them through the skin/muscle for anchoring as it improved the fish welfare during surgery. Surgical wound showed complete skin/peritoneal apposition with regenerated skeletal muscle, fibrosis, lymphocyte-like cells and vascularization at the site three weeks post-surgery. Following surgery, heart rate (fH) was elevated (˃70 beats min⁻¹) which stabilized 3 days post-surgery in tests 1 & 3. However, it took at least 10 days to stabilize fH in case of test 2. All three stress tests inflicted tachycardia suggesting aquaculture practices incur stress in farmed Atlantic salmon. Heart rate was raised at stress (range 62–78 beats min⁻¹) as compared to pre-stress levels (range 44–48 beats min⁻¹) that corresponds to 42–77% elevation in all three tests. Cortisol levels were upregulated following tests but only significantly different in test 3. This study reveals that physiological responses (heart rate) should be combined with histological evaluation of surgical healing before utilizing the heart rate (fH) data. Upon handling, fish should be given enough time (˃48 h) to stabilize fH levels before commencing to other tests/handlings. In conclusion, heart rate can be used for continuous fish welfare monitoring under farming conditions.
... Over the past few decades, many conventional methods have been applied to analyse the gut microbiota of fish 54 but recently with the development of molecular techniques such as next-generation sequencing (NGS), a rapid and low-cost technique, research on the gut microbiota of fish has evolved rapidly 46 . Like humans and other mammals, there is little doubt concerning the importance of the intestinal microbiota for fish health 22,55,56 , however, dysbiosis of the intestinal microbiota could also be related to growth impairment, dysregulation of immune functions and disease development in fish 57,58 . A recent study 22 , has reported the modulatory effects of alternative protein sources on the intestinal microbiota in barramundi but possible links between diets, growth, and gut functions is fragmentary and incomplete. ...
The effects of feeding different levels of poultry by-product meal (PBM) replacing fishmeal (FM) protein, supplemented with tuna hydrolysate (TH) and Hermetia illucens (HI) larvae, on the growth, fillet quality, histological traits, immune status, oxidative biomarker levels and gut microbiota of juvenile barramundi, Lates calcarifer were investigated for six weeks. Barramundi were fed four isonitrogenous and isolipidic diets in which a FM based diet was used as the Control diet (Diet1) and compared with other non-FM diets containing 80%, 85% and 90% PBM along with the concurrent supplementation of 5% and/or 10% TH and HI larvae meal. These treatment diets were designated as 80PBM 10TH+10HI (Diet2), 85PBM 5TH+10HI (Diet3) and 90PBM 5TH+5HI (Diet4). The growth and condition factor of fish fed 80PBM 10TH+10HI and 85PBM 5TH+10HI were significantly higher than the Control. Total saturated, monounsaturated and polyunsaturated fatty acid retention in the fish muscle increased in fish fed PBM-based diets, supplemented with TH and HI larvae meal, with no adverse effect on post-harvest characteristics such as texture and colour of fish fillets. Improvement in serum total bilirubin and total protein content was found in all fish fed TH and HI larvae supplemented PBM. Similarly, immune response showed a significant increase in fish fed non-FM test diets than the Control. In the distal intestine, supplementation of any quantities of TH and HI larvae to PBM led to an increase in the microvilli density and neutral mucins while the number of goblet cells in the skin were unchanged. Liver, kidney, and spleen histology demonstrated a normal structure with no obvious changes in response to all test diets. Bacterial diversity increased in fish fed Diets 2 and 3 with a high abundance of Proteobacteria in Diets 1 and 4 and Firmicutes in Diets 2 and 3. The fish on test diets showed a lower abundance of genus Vibrio. Fish fed TH and HI larvae supplemented PBM diets showed lower infection rate to V. harveyi than the Control. Collectively, concurrent supplementation of TH and HI larvae could improve the quality of PBM diets with positive effects on growth, fillet quality, intestinal health, immunity, and disease resistance. Due to a favourable nutritional profile, compatible with the nutritional requirement of most aquaculture species 1 , the aquaculture industry has traditionally relied on fishmeal (FM) as the main protein source 2. Since this dietary protein source is considered environmentally and ecologically unsustainable, there is societal and economical pressure on the aquaculture industry to search for alternative protein ingredients. Efforts have been dedicated over the past few decades to utilize plant-feedstuffs to replace FM 1 however the resulting growth performance OPEN
... However, this method requires some sacrificial fishes. Alternatively, a direct blood measurement was utilized to measure the nutrient bioavailability in the fish [151,152]. ...
Digestive systems in human, animals, and fish are biological reactors and membranes to digest food and extract nutrients. Therefore, static and dynamic models of in-vitro digestion systems are developed to study e.g. novel food and feed before in-vivo studies. Such models are well developed for human, but not to the same extent for animals and fish. On the other hand, recent advances in aquaculture nutrition have created several potential fish meal replacements, and the assessment of their nutrient digestibility is critical in the application as a fish meal replacement. Using an in-vitro method, the assessment of an ingredient digestibility could be faster and less expensive compared to using an in-vivo experiment. An in-vitro method has been widely used to assess food nutrient digestibility for humans; however, its application for fish is still in the early stages. Both the human and fish as monogastric vertebrates share similar gastrointestinal systems; thus, the concept from the application for humans could be applied for fish. This review aims to improve the in-vitro digestion protocol for fish by adapting the concept from then study for humans, summarizing the current available in-vitro digestion model developed for human and fish in-vitro digestion study, identifying challenges specifically for fish required to be tackled and suggesting an engineering approach to adapt the human in-vitro gastrointestinal model to fish. Protocols to conduct in-vitro digestion study for fish are then proposed.
... Yeast is an exceptional SCP since it contains a moderate protein level, is abundant in lysine, has low toxic potential, can be cultivated on a wide range of substrates and is relatively easy to produce [146][147][148]. Yeast is a source of many essential B vitamins and has a balanced amino acid profile, except for sulphur-containing amino acids. ...
... Work on the application of fungal SCP resources in the diets of salmonids has been an especially prolific area of research in recent years [41,58,59,148,149]. The use of yeast as a dietary protein for farmed fish is not a new concept, as studies have investigated this possibility since the 1970s. ...
Single-cell ingredients (SCI) are a relatively broad class of materials that encompasses bacterial, fungal (yeast), microalgal-derived products or the combination of all three microbial groups into microbial bioflocs and aggregates. In this review we focus on those dried and processed single-cell organisms used as potential ingredients for aqua-feeds where the microorganisms are considered non-viable and are used primarily to provide protein, lipids or specific nutritional components. Among the SCI, there is a generalised dichotomy in terms of their use as either single-cell protein (SCP) resources or single-cell oil (SCO) resources, with SCO products being those oleaginous products containing 200 g/kg or more of lipids, whereas those products considered as SCP resources tend to contain more than 300 g/kg of protein (on a dry basis). Both SCP and SCO are now widely being used as protein/amino acid sources, omega-3 sources and sources of bioactive molecules in the diets of several species, with the current range of both these ingredient groups being considerable and growing. However, the different array of products becoming available in the market, how they are produced and processed has also resulted in different nutritional qualities in those products. In assessing this variation among the products and the application of the various types of SCI, we have taken the approach of evaluating their use against a set of standardised evaluation criteria based around key nutritional response parameters and how these criteria have been applied against salmonids, shrimp, tilapia and marine fish species.
