Growth Performance Of Rainbow Trout Research Articles

Mechanism of Ligilactobacillus salivarius GX118 in Regulating the Growth of Rainbow Trout (Oncorhynchus mykiss) and Resistance to Aeromonas salmonicida Infection

Lactic acid bacteria Ligilactobacillus salivarius has been shown to be a substitute for antibiotics in the treatment of bacterial disease in high animals. However, its beneficial mechanism in fish farming is still unclear. This study evaluated the antagonistic effects of the Ligilactobacillus salivarius GX118 strain on Aeromonas salmonicida and its regulation of rainbow trout growth in vivo and in vitro. The results found that GX118 produces an antibacterial substance that can directly destroy the cell wall of A. salmonicida. Whole-genome sequencing of GX118 revealed that Enterolysin A is a type III bacteriocin with antibacterial properties. An in vivo experiment showed that the supplementation of GX118 in diet competitively inhibited the colonization of A. salmonicida in the intestine. In addition, it was able to improve the growth performance of rainbow trout within a 21-day feeding experiment. The supplementation of GX118 increased the diversity of gut microbiota, in which the abundance of Bacteroidota, Blautia, and Rhodobacteraceae increased. In addition, the use of GX118 activated the expression of IFN-γ and NF-κB genes and reduced the expression level of IL-6 and IL-8, thus exhibiting a certain effect on activating the immunity of rainbow trout. This study provides a scientific basis for the development of antibacterial probiotics in the healthy farming of rainbow trout.

Effects of dietary pectin on the growth performance, intestinal barrier, and antioxidant status of juvenile rainbow trout (Oncorhynchus mykiss)

To evaluate the effects of dietary pectin on growth performance, intestinal barrier, and antioxidant status of juvenile rainbow trout (Oncorhynchus mykiss), 10-week feeding trial was conducted. Five isoproteic and isoenergetic diets were formulated to contain 0% (P0), 4% (P4), 8% (P8), and 16% (P16) pectin as well as 0.02% pectinase (PE) at the expense of wheat starch, respectively. Dietary inclusion of 416% pectin linearly promoted the feed intake and growth performance but depressed the feed efficiency, but significant differences were only observed between the P16 and P0 groups. Similarly, dietary inclusion of 816% pectin significantly increased the foregut trypsin and amylase activities but decreased the foregut and midgut sucrase activity. The midgut muc2 gene expression level was significantly down-regulated by the inclusion of 16% pectin. Dietary inclusion of 2% pectin increased the abundance of Proteobacteria and Stenotrophomonas but reduced the abundance of Actinobacteria, Bacteroides and Helicobacter; while the lowest values of observed species, Chao1 and ACE indices of intestinal flora were found in the P8 group. Fish fed with the P8 diet exhibited the lowest plasma catalase and midgut glutathione S-transferase activities as well as malondialdehyde content, but the highest midgut malondialdehyde content. Dietary inclusion of 816% pectin significantly depressed the plasma growth hormone (GH), insulin-like growth factor-1 (IGF-1) and mechanistic target of rapamycin contents as well as alanine aminotransferase activity, the hepatic adenosine monophosphate deaminase and glutamate dehydrogenase (GDH) activities. Dietary treatment with 0.02% pectinase did not affect the growth performance, but depressed the foregut sucrase activity, the midgut amylase and sucrase activities, increased the plasma GH and IGF-1 contents as well as hepatic GDH and aspartate aminotransferase activities. In conclusion, high-dose of dietary pectin (816%) may promote the feed intake and intestinal digestive enzyme activities and thereby improve the growth performance of rainbow trout.

Exploring the effects of dietary inulin in rainbow trout fed a high-starch, 100% plant-based diet

BackgroundHigh dietary carbohydrates can spare protein in rainbow trout (Oncorhynchus mykiss) but may affect growth and health. Inulin, a prebiotic, could have nutritional and metabolic effects, along with anti-inflammatory properties in teleosts, improving growth and welfare. We tested this hypothesis in rainbow trout by feeding them a 100% plant-based diet, which is a viable alternative to fishmeal and fish oil in aquaculture feeds. In a two-factor design, we examined the impact of inulin (2%) as well as the variation in the carbohydrates (CHO)/plant protein ratio on rainbow trout. We assessed the influence of these factors on zootechnical parameters, plasma metabolites, gut microbiota, production of short-chain fatty acids and lactic acid, as well as the expression of free-fatty acid receptor genes in the mid-intestine, intermediary liver metabolism, and immune markers in a 12-week feeding trial.ResultsThe use of 2% inulin did not significantly change the fish intestinal microbiota, but interestingly, the high CHO/protein ratio group showed a change in intestinal microbiota and in particular the beta diversity, with 21 bacterial genera affected, including Ralstonia, Bacillus, and 11 lactic-acid producing bacteria. There were higher levels of butyric, and valeric acid in groups fed with high CHO/protein diet but not with inulin. The high CHO/protein group showed a decrease in the expression of pro-inflammatory cytokines (il1b, il8, and tnfa) in liver and a lower expression of the genes coding for tight-junction proteins in mid-intestine (tjp1a and tjp3). However, the 2% inulin did not modify the expression of plasma immune markers. Finally, inulin induced a negative effect on rainbow trout growth performance irrespective of the dietary carbohydrates.ConclusionsWith a 100% plant-based diet, inclusion of high levels of carbohydrates could be a promising way for fish nutrition in aquaculture through a protein sparing effect whereas the supplementation of 2% inulin does not appear to improve the use of CHO when combined with a 100% plant-based diet.

Effects of dietary corn and protein levels on physical properties of extruded feed pellets and growth performance of rainbow trout, Oncorhynchus mykiss

AbstractThe dietary protein levels and source of starch are factors in the economical production of feeds, which may change the physical quality of extruded pellets and the growth performance of fish. Eight feeds contained two protein levels and four levels of wheat flour substitutions by corn, as a 2 × 4 factorial experimental design, were produced by a twin‐screw extruder machine and fed to 800 rainbow trout. The results showed corn grain reduced expansion ratio, water stability at 120 and 260 min, starch gelatinization (SG), and apparent degradability, while bulk density (BD) and oil leakage of feed pellets increased. The high protein diets displayed the most BD, lower oil leakage, SG, and elastic modulus. The high protein feeds improved the final body weight, weight gain, specific growth rate, and feed conversion ratio (FCR) of fish. The corn grain reduced the FCR and promoted the trout's protein efficiency ratio. Lipid proportions of fish livers corresponded to hepatosomatic index and serum concentrations of aspartate aminotransferase and alanine aminotransferase. In general, corn, as the starch source in the high and low‐protein extruded feeds, can be replaced at levels of 33%–66% of wheat flour without adverse effects on the physical characteristics of feed pellets and the growth performance of rainbow trout.

Effects of dietary arachidonic acid supplementation in low fishmeal and fish oil-free diets on growth performance, inflammatory response, gut histology, and non-specific immunity in sub-adult rainbow trout, Oncorhynchus mykiss

Arachidonic acid (ARA) is becoming increasingly important due to significant reductions in fishmeal (FM) and fish oil (FO), the primary sources of ARA, in aquafeeds. ARA is an essential omega-6 fatty acid in some fish species and plays a wide range of physiological roles. However, studies reported to date have demonstrated contrasting findings concerning the effects of ARA in fish growth and health, regardless of the fish's trophic level. Additionally, limited research has addressed energy allocation during reproduction and growth in sub-adult rainbow trout as they approach reproductive maturity. Therefore, a study was conducted to evaluate the effects of different levels of ARA on growth performance, the fatty acid composition of whole-body and ovary, intestinal inflammatory gene expression, gut histology, antioxidant activity, and non-specific immunity in sub-adult rainbow trout (Oncorhynchus mykiss). Four isonitrogenous (51% crude protein), isolipidic (15% crude lipid), and isocaloric (23 MJ/kg) diets were formulated and supplemented with ARA-enriched oil (40%), resulting in analyzed ARA levels of 0.10 (ARA0.10), 3.95 (ARA3.95), 7.67 ARA(7.67), and 14.8% (ARA14.8) of total fatty acid, respectively. Rainbow trout (307 ± 3.64 g) were fed to apparent satiation three times a day for 12 weeks to assess growth performance, feed utilization, and intestinal inflammatory response. The fish were then exposed to acute stress to evaluate circulating cortisol, prostaglandin E2, antioxidant activity, and non-specific immune response. The 12-week growth trial demonstrated that dietary ARA did not affect rainbow trout growth performance and feed utilization during the final grow-out. Whole-body fatty acid profiles reflected those of the diets except for eicosapentaenoic acid (EPA) content being significantly lower in the ARA14.8 group than in the ARA0.10 and ARA3.95 groups. EPA and docosahexaenoic acid (DHA) contents in the ovary were less affected by dietary ARA supplementation, likely reflecting the selective deposition of those fatty acids in embryonic development. The expression of tnf-α was significantly downregulated in ARA7.67 and ARA14.8 groups relative to other treatment groups, and only distal intestinal villus height was significantly increased in the ARA3.95 group, suggesting that dietary ARA supported intestinal health. Plasma superoxide dismutase, catalase, and lysozyme activity significantly increased in both pre- and post-stress groups due to incremental increases in dietary ARA. These results suggest that a moderate level of dietary ARA in low FM and FO-free enhances innate immune function and antioxidant responses while supporting intestinal health in sub-adult rainbow trout.

Effect of Dietary Soy Protein Source on Effluent Water Quality and Growth Performance of Rainbow Trout Reared in a Serial Reuse Water System.

Juvenile rainbow trout (125 ± 0.8 g) were fed a fishmeal control diet (C), a high soy protein concentrate diet (SP), a high soybean meal diet (HiS), or a diet with high levels of fermented soy protein concentrate (fSP) for 12 weeks in a tank system capable of receiving 1st and 3rd use water from a serial-reuse production hatchery. Water quality was generally lower in 3rd use compared to 1st use water and after passing through tanks (inflow vs. outflow). Total dissolved solids were significantly higher (p = 0.003) for 3rd use compared to 1st use water, and values were also higher (p < 0.001) for the fSP diet. Turbidity and ammonia were highest in tanks for trout fed the HiS and fSP and SP and fSP diets, respectively, but were characterized by high variation, which likely prevented the detection of significant differences. Weight gain (p < 0.001) and survival (p = 0.008) were significantly lower for trout in 3rd use compared to 1st use water. Trout fed the HiS diet were generally in poorer physiological condition with lower body fat stores (p = 0.05) and lower growth rate (p < 0.001) and survival (p = 0.05) compared to the other diets, which were similar. The expression of several stress-associated genes (FK506, DIO2, REGPS, Cyp1a, G6PH, GADD45a, and IRF-1) in the liver and gill showed that diet and water source affected their regulation. Replacement of FM by SP providing 50% of dietary protein promotes acceptable growth performance compared to an FM diet and was superior to HiS. The impacts of soy protein concentrate on water quality under commercial production conditions, however, require further study.

Growth performance of Rainbow Trout in reservoir tributaries and implications for steelhead growth potential above Skagit River dams

AbstractObjectiveIn the Pacific Northwest (USA), Pacific salmon Oncorhynchus spp. populations have been declining significantly for decades, prompting stakeholders to respond with a variety of conservation and restoration measures. One such measure being considered in the Skagit River basin (Washington, USA) is the introduction of steelhead Oncorhynchus mykiss (anadromous Rainbow Trout) above the impassable Gorge, Diablo, and Ross dams to bolster their populations. Because freshwater growth is key to survival at subsequent life stages, we evaluated current trends in size and growth of Rainbow Trout among key tributaries to Gorge, Diablo, and Ross reservoirs using empirical data collection and bioenergetics modeling.MethodsFor nine candidate streams, a bioenergetics model was used to assess how temperature and prey consumption affected growth performance of Rainbow Trout between annuli 1 and 2, and 2 and 3. Thermal scenarios were created to evaluate how fish growth responded to temperature variability while total annual consumption was constrained within empirical growth estimates. We then compared these results to back‐calculated size thresholds established by size‐at‐age observed in wild steelhead adults that returned to the Skagit River below the dams.ResultOf the streams proposed for introductions, there was one instance (McMillan Creek) in the nominal simulations where growth met or exceeded the size at annulus 2 or 3 of a returning adult steelhead (24.9 g at annulus 2 and 50.3 g at annulus 3). Modeled growth under different thermal scenarios showed that colder temperatures (0.1–10.7°C, Canyon Creek) produced higher growth than under the nominal or warm scenarios (2.0–15.3°C, Canyon Creek), as well as one additional tributary where size at annulus 2 or 3 (±2 SE) was comparable to the threshold established by adult steelhead below the dams (Big Beaver Creek, annulus 3).ConclusionThese results suggest Rainbow Trout growth is most limited by prey availability in the examined upper Skagit tributaries.

Effects of dietary probiotics and probiotics combined with enzymes on growth performance of rainbow trout (Oncorhynchus mykiss)

Effects of dietary probiotics and probiotics combined with enzymes on growth performance of rainbow trout (Oncorhynchus mykiss)

Effects of Dietary Protein and Lipid Levels on Growth, Metabolism, Antioxidative Capacity, and Fillet Quality of Adult Triploid Rainbow Trout Farmed in Net Cage.

The research is aimed at investigating the effects of dietary protein and lipid levels on adult triploid rainbow trout growth performance, feed utilization, digestive and metabolic enzyme activities, antioxidative capacity, and fillet quality. Nine diets containing three dietary protein levels (DP) (300, 350, and 400 g kg-1) and three dietary lipid levels (DL) (200, 250, and 300 g kg-1) were prepared using a 3 × 3 factorial design. In freshwater cages, 13,500 adult female triploid rainbow trout (3.2 ± 0.1 kg) were cultured for 77 days. Triplicate cages (500 fish per cage) were used as repetitions of each experimental diet. The findings revealed that as DP increased to 400 g kg-1 and DL raised to 300 g kg-1, the weight gain ratio (WGR) elevated significantly (P < 0.05). However, when DP ≥ 350 g kg-1, WGR was similar in the DL250 and DL300 groups. As DP raised to 350 g kg-1, the feed conversion ratio (FCR) notably decreased (P < 0.05). In the DP350DL300 group, lipids had a protein-sparing impact. High DP diet (400 g kg-1) generally improved fish health status by increasing antioxidant capacity in the liver and intestine. A high DL diet (300 g kg-1) showed no harmful effect on hepatic health based on plasma levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and antioxidant capacity in the liver. For fillet quality, a high DP diet could increase fillet yield, improve fillet hardness, springiness, and water-holding capacity values, and inhibit the production of off-flavors caused by n-6 fatty acids. A high DL diet could increase odor intensity, and EPA, DHA, and n-3 fatty acid concentrations decrease the thrombogenicity index value. The maximum fillet redness value was discovered in the DP400DL300 group. Overall, for adult triploid rainbow trout (≥3 kg), the minimum recommended DP and DL according to growth performance were 400 and 250 g kg-1, respectively; DP and DL based on feed utilization were 350 and 200 g kg-1, respectively; DP and DL based on fillet quality were 400 and 300 g kg-1, respectively.

Effect of dietary butyric acid, Bacillus licheniformis ‎ (probiotic), and their combination on hemato-biochemical indices, antioxidant enzymes, immunological parameters, and growth performance of Rainbow trout (Oncorhynchus mykiss)

This study was performed to investigate the effects of dietary butyric acid, probiotic (Bacillus licheniformis‎), and their combination on hematology and biochemical indices, liver antioxidant enzymes, immune parameters, and growth performance of rainbow trout (Oncorhynchus mykiss). Three hundred healthy rainbow trout fish (average initial weight = 13.33 ± 0.20 g) were fed four isonitrogenous (40.99 g kg-1 crude protein) diets. The first diet (D1) was control. The other three diets D2, D3and D4 were supplemented with 2.2. × 107 CFU g-1B.licheniformis, 2 % butyric acid and 2 % butyric acid + 2.2. × 107 CFU g-1B.licheniformis diet, respectively. The results indicated that fish receiving diets 3 and 4 have the highest hematology parameters, total protein, albumin, and globulin. No significant difference (P > 0.05) was observed in the serum level of alanine aminotransferase (ALT), alkaline ‎phosphatase (ALP), ‎ and liver superoxide dismutase (SOD) activity among experimental diet groups. The liver catalase (CAT) and glutathione peroxidase (GPX)‎ activity were significantly in fish fed with diets 2, 3, and 4 (P < 0.05). The most improvement in total immunoglobulin (Ig) concentration, lysozyme, and serum bactericidal activity were observed in fish fed with diets 3 and 4 (P < 0.05). The challenge test showed that the order of resistance to S. agalactiae infection was in fish fed with diets 3, 4, and ‎2, respectively. The fish fed with diet 4 exhibited the lowest feed conversion ratio and the highest final body weight, weight gain, and specific growth rate (P < 0.05). In general, this study showed that dietary administration of butyric acid alone or ‎combined with B. licheniformis provides promising results as a functional feed for the ‎rearing of rainbow trout.‎

Physiological response of rainbow trout (Oncorhynchus mykiss) to graded levels of novel Chlorella sorokiniana meal as a single fishmeal alternative or combined with black soldier fly larval meal

Chlorella meal is a potential single-cell protein source for fishmeal replacement in aquafeed. However, it is still challenging to incorporate Chlorella meal in diets of carnivorous fish at high inclusion level due to its rigid cell wall and lower nutritional quality compared with fishmeal. This study was conducted to investigate novel cell wall-ruptured Chlorella sorokiniana GT-1 meal alone or combined with black soldier fly larval meal (BSFM) as substitute ingredient to dietary fishmeal for rainbow trout, Oncorhynchus mykiss. Nine isonitrogenous (43% crude protein) and isolipidic (17% crude lipid) diets were formulated: a control diet (fishmeal-based) and eight experimental diets replacing fishmeal by 25%, 50%, 75% and 100% with C. sorokiniana meal; 25%, 50%, 75% and 100% with C. sorokiniana meal + BSFM blended with 50:50 ratio (C. sorokiniana meal + BSFM). A total of 540 fish (initial body weight of 67.65 g) were randomly distributed to 27 tanks (20 individuals/tank) with the nine diets in triplicate. The fish were hand-fed experimental diets to apparent satiation twice daily for 8 weeks. The results showed improved growth performance and feed intake in rainbow trout fed a C. sorokiniana meal-based diet (C5). The C. sorokiniana meal-based diet also resulted in higher villi height and greater muscular layer thickness of the proximal intestine, improved intestinal barrier integrity, and healthier gut microbiota with increased Lactobacillus and decreased Acinetobacter compared with the controls. There was no improvement in growth performance of rainbow trout fed a diet based on a mixture of C. sorokiniana meal and BSFM (C9), and no significant difference was observed between C9 and the control group. However, decrease in intestinal inflammation and improvement of bacterial diversity were observed by blending C. sorokiniana meal and BSFM. In addition, shifts in amino acid metabolism and elevation of fatty acid metabolism were found in C5 and C9. Upregulation of mechanistic target of rapamycin (mTOR) pathway-related genes in liver and intestine was also observed in C5 and C9. The findings suggest that the novel C. sorokiniana meal as a single substitute ingredient or combined with BSFM has the potential to replace dietary fishmeal at high inclusion levels in rainbow trout.

Taurine supplementation in plant-based diets for juvenile rainbow trout (Oncorhynchus mykiss): Effects on growth performance, whole body composition, and histomorphological features

Taurine supplementation in plant protein-based diets has been reported to improve growth performance, feed utilization, whole body composition, and gut integrity in carnivorous fish species, but data in rainbow trout are quite scarce. This study aimed to investigate the effects of plant protein-based diets supplemented with different levels of taurine on rainbow trout growth performance, whole body composition, and histomorphological traits of the intestine and main organs. In a 71-day trial, 340 juvenile rainbow trout were randomly distributed to 5 dietary treatments (4 replicate tanks/diet, 17 fish/tank): two control diets (a fishmeal-based diet [positive control; C+] and a soybean meal-soy protein concentrate-based diet [negative control; C-]), and three experimental diets in which the C-diet was supplemented with 2.5, 5 and 10 g/kg of taurine (T2.5, T5 and T10, respectively). At the end of the trial, growth parameters were assessed, and whole fish (12 pools of 3 fish/diet) and gut, liver and kidney samples (12 fish/diet) were collected for whole body composition and histomorphological analyses, respectively. Liver (8 fish/diet) was also sampled for taurine quantification. The fish fed the T10 diet showed higher weight gain, protein efficiency ratio, and specific growth rate – as well as decreased feed conversion ratio – when compared to the C+ group only (P < 0.05), thus suggesting a main effect of the taurine source on the response. The T2.5 rainbow trout showed lower moisture content and increased ether extract and ash contents than the other dietary treatments (P < 0.001). Higher crude protein content was also observed in fish fed the C- and T10 diets in comparison with the other groups (P < 0.001). Hepatic taurine levels were increased in the C+ group when compared to the C-, T2.5 and T5 diets (P < 0.05), with higher contents being also identified in the T10 group than the C- diet (P < 0.01). Differently, gut morphometric indices and histopathological features of the gut, liver, and kidneys were unaffected by dietary taurine supplementation (P > 0.05). In conclusion, dietary taurine supplementation in juvenile rainbow trout fed vegetable protein-based diet is capable of influencing the growth performance and the whole lipid content of the animals, without affecting the histomorphological traits of the intestine, the liver and the kidneys. In particular, the 2.5 and 10 g/kg supplementation levels seem to be capable of exerting the most pronounced effects in terms of composition of the fish body mass and growth parameters, respectively.

Shiitake Mantar Ekstraktı İlaveli Yemlerin Gökkuşağı Alabalığında (Oncorhynchus mykiss) Büyüme, Non-Spesifik İmmun Parametreler ve in-vitro Aeromonas hyrophila Enfeksiyonuna Karşı Direnç Üzerine Etkileri

The activity of Lentinula edodes (shiitake) medicinal mushroom extract were examined on the non-specific immune response and biometrical performance of rainbow trout (Oncorhynchus mykiss). Fish (20 g initial weight) were divided into 3 treatment groups (60 fish/group) and duplicated groups for 6 weeks having two experimental diets supplemented with 1-2% shiitake extract and a control diet. During the feeding process, immunological, biochemical, and biometrical observations were determined using the fish and blood samples taken at weeks 1, 2, 3, 4, 5, and 6, respectively. The results of immunological, biochemical, and biometrical parameters evaluation determined that the maximum influence occurs in rainbow trout fed with 2% shiitake extract. The amount of respiratory burst activity in the blood of fish in the trial groups significantly increased in each diet on the 2nd and 6th weeks compared to controls. The amount of total protein, bactericidal activity were significantly increased in fish being fed a mushroom supplemented diet. Cholesterol level decreased in fish blood, which fed with 2% shiitake extract supplemented diet at 3rd and 6th weeks. These results support the findings that the non-specific immune responses of rainbow trout was stimulated in fish by feeding shiitake medicinal mushroom extract yielding positive results in measured parameters compared to the control group also enhancing the overall growth performance of rainbow trout.

In Vitro and in Vivo Characterization of Inosine Monophosphate Delivered by a Nanoparticle in Rainbow Trout

AbstractRainbow Trout Oncorhynchus mykiss are a commonly farmed fish worldwide and, as such, are of economic importance in many countries. Inosine monophosphate (IMP) has been shown to have a positive effect on Rainbow Trout growth performance and overall health. The aim of the current study was to test whether a novel phytoglycogen nanoparticle (NP) was nontoxic and if it could enhance the positive effects of IMP on Rainbow Trout health at the cellular and whole‐animal level. The NP used in this study is derived from sweet corn and can act as a carrier, delivering its payload to the cell. The NP was chemically modified to covalently bind IMP. The effects of four experimental groups were tested on Rainbow Trout at the in vitro and in vivo level: untreated control, NP alone, IMP alone, and IMP covalently conjugated to the NP (IMP‐NP). The effects of the four experimental groups were measured at the cellular level using a Rainbow Trout intestinal epithelial cell line (RTgutGC). Cellular metabolism was significantly increased in RTgutGC when treated with IMP‐NP for 24 and 48 h compared with NP or IMP alone. These treatments did not result in a compromised cell membrane, with the exception of minimal membrane integrity loss at 48 h with the higher doses of IMP‐NP. During the 48‐h time frame, enhanced metabolism did not result in enhanced cell proliferation. A pilot study was performed in Rainbow Trout to test the safety of the NP to fish. Over an 8‐week feeding trial, no mortalities were observed. Additionally, intestinal villi density increased with IMP‐NP and NP treatments, while villus height and width were unaffected. This study introduces the use of a phytoglycogen‐based NP as a novel delivery system for IMP that is able to increase metabolism at the cellular level and is nontoxic in Rainbow Trout.

Chitosan Polymeric Nanoparticles as a Carrier of &lt;i&gt;Thymbra spicata&lt;/i&gt; Hydroalcoholic Extract: Effect on Growth Parameters in Rainbow Trout (&lt;i&gt;Oncorhynchus mykiss&lt;/i&gt;)

This study aimed to investigate the effect of using chitosan polymeric nanoparticles (CNPs) on improving the efficiency of hydroalcoholic extract of Thymbra spicata (TS) on the growth parameters of rainbow trout (Oncorhynchus mykiss) fed with the experimental diets containing different levels of TS extract with and without CNPs. Thymbra spicata loaded chitosan polymeric nanoparticles (TSCNPs) were prepared by ionic gelation methods in the presence of sodium tripolyphosphate (TPP). The fourier transform infrared spectroscopy (FT-IR) of TSCNPs showed that the strong peaks due to hydroxyl groups (OH) and alcohol and amine (NH) were shifted to 3427 cm−1, and peak wide has expanded due to increased hydrogen bonds. The FT-IR results were proved the interaction of CNPs and TS extract. The scanning electron microscope (SEM) imaging showed a spherical shape, smooth and homogeneous structure for nanoparticles. In zetasizer results, nanoparticles size average, poly dispersity index (PDI), zeta potential (ZP), and zeta average (d.nm) were 86.1 nm, 0.21, 31.3 mV, and 83.3, respectively. In energy dispersive spectroscopy (EDS) results, the major compounds of TSCNPs included C, O, Al, Cl, Mg, K, and Ca. At the UV-Visible spectrum, the absorption of TS extract based on the absorption of flavonoids was observed at 430 nm. Obtained results showed that the encapsulation efficiency (EE) of the nanoparticles was 94.1%. In vitro, a gradual and acidic dependent period of 120 h was observed in TS release conditions. After eight weeks of feeding, the addition of 400 mg kg-1 diet of TSCNPs resulted in significant improvement in the final weight, final length, specific growth rate (SGR), and survival (S) (P &lt; 0.05). This research suggests that loading Thymbra spicata hydroalcoholic extracts on chitosan polymeric nanoparticles increased the efficiency of plant extract compared to extract pure form and improved the growth performance in rainbow trout.

The First Commercially-Scaled Study on the Influence of Long Dark and Light Photoperiod Manipulation on the Egg and Larvae Performance of Rainbow Trout (Onchorhynchus mykiss)

Engin, S., 2022. The first commercially-scaled study on the influence of long dark and light photoperiod manipulation on the egg and larvae performance of rainbow trout (Onchorhynchus mykiss). Journal of Coastal Research, 38(1), 196–203. Coconut Creek (Florida), ISSN 0749-0208. Spawning success, number of eyed-egg, and larval growth performance of rainbow trout are largely affected by a variety of biotic and abiotic factors. The photoperiod is important in initiating or suppressing breeding timing and gonadal maturation that varies by species. The aims of this study were to investigate the effect of two different commercial photoperiod manipulations on the growth of total eyed eggs, egg diameter, and larvae under specific fish farm conditions. The control group (outdoor broodstock ponds and natural sunlight) fish were fed using a commercial broodstock feeding protocol in September and transferred to the hatchery in February for spawning. The female and male broodstocks were exposed to direct photoperiod (Experimental Group 1: M1), and for the adapted photoperiod (transition from light to dark periodically, Experimental Group 2: M2) they were exposed to 18 hours of light and 6 hours of darkness between January and April. The M1 group were exposed to a direct application of 18 hours of dark and 6 hours of light, and a transition from light to dark for 18 hours and from dark to light for 6 hours was applied to M1 that was completed over 48 days with a daily decrease of 17 minutes. The results of the trials showed that larval growth was higher in the groups treated with long light and long dark, 18 hours light/6 hours dark and 18 hours dark/6 hours light compared to the control group, and statistically significant difference between larval survival rate and daily weight gain was observed between all three groups (p < 0.05). As a result, at the end of the photoperiod, applications and larvae breeding performed for one year under commercial operating conditions were compared, and larvae with higher survival and growth rates were obtained with long light and long dark application.

Evaluation of an Innovative and Sustainable Pre-Commercial Compound as Replacement of Fish Meal in Diets for Rainbow Trout during Pre-Fattening Phase: Effects on Growth Performances, Haematological Parameters and Fillet Quality Traits.

Simple SummaryThe study aims to define the potential and sustainable use of pre-commercial product ITTINSECT™ APS V1 as fish meal replacement in the diets of rainbow trout Oncorhynchus mykiss. For this, a 60 days feeding trail was performed by using diets with different replacing rate of fishmeal (0 (ITTM0), 25 (ITT25), 50 (ITT50), 75 (ITT75) and 100 (ITT100) %) with ITTINSECT™ APS V1. At the end of the feeding trial, significantly higher growth performance was observed in the group fed with the diet with a 25% and 50% substitution of fish meal by ITTINSECT™ APS V1. Moreover, the growth-related gene expressions analyzed in muscle tissue had significantly higher gene expression levels for these two diets (25% and 50% substitution) when compared to the control. The hematology values were found to be identical, whereas other parameters (such as serum total protein, globulins and glucose levels, or some immune-related gene expression) had different results among the experimental groups. In conclusion, replacement of fish meal with up to 50% ITTINSECT™ APS V1 in diets for rainbow trout is suggested in order to achieve the best growth performance in rainbow trout and enhance sustainable aquaculture practices.The aim of the study was to determine the potential and sustainable use of pre-commercial product ITTINSECT™ APS V1 as a major protein source in rainbow trout (Oncorhynchus mykiss) diets. A 60-day feeding experiment was conducted to potentially use ITTINSECT as fish meal replacement in the diets of rainbow trout. Five isonitrogenous in dry matter (38% crude protein) and isolipidic (15% crude lipid) diets were produced: a control diet (fishmeal-based) (ITT0) and four experimental diets replacing fishmeal by 25 (ITT25), 50 (ITT50), 75 (ITT75) and 100 (ITT100) %, with ITTINSECT™ APS V1. Triplicate tanks, containing 15 fish each (65.81 ± 1.26 g), were hand-fed to apparent satiation twice every day during the experiment. At the end of the feeding trial, significantly higher growth performance was observed in the group fed ITTM25 and ITTM50 diets. This performance was supported by growth-related gene expressions analyzed in muscle; significantly higher GH and IGF-I genes expression levels were determined in ITT25 and ITT50 when compared to control (ITT0) (p < 0.05). While no significant differences were found between the hematology values (p > 0.05), serum total protein, globulins and glucose levels were significantly different between experimental groups (p < 0.05). In addition to this, the immune-related genes such as TNF-α, IL8 and IL1-β expression levels were determined to be significantly different (p < 0.05). In conclusion, in order to achieve the best growth performance in rainbow trout and enhance sustainable aquaculture practices, replacement of fish meal with up to 50% ITTINSECT™ APS V1 in diets for rainbow trout is suggested.

Effects of diets containing β‐glucan on survival, growth performance, haematological, immunity and biochemical parameters of rainbow trout ( Oncorhynchus mykiss ) fingerlings

This study aimed to investigate the effect of β-glucan in rainbow trout's diet on survival, growth performance, haematological, immunity and biochemical parameters. Rainbow trout (Oncorhynchus mykiss) with an average weight of 6.33 ± 0.09 were stocked in 30 fibreglass tanks with a volume of 200 L. Four treatments including control group (0%), 0.05%, 0.1% and 0.2% of β-glucan were considered for 8 weeks. The results showed that the survival and growth performance of rainbow trout in the control group were at the lowest level and showed a significant difference (p < 0.05) with other treatments. The highest percentage of haematocrit (47.9%), white blood cell count and neutrophil percentage (35.2%) was observed in the treatment with 0.2% β-glucan. Also, the highest lysosomal activity (59.7 units’ ml−1), IgM (54.7 mg dl−1), C3 and C4 was obtained in 0.2% β-glucan treatment. Biochemical parameters indicated improvement in treatments fed with 0.1 and 0.2% β-glucan. In conclusion, the present study suggested that 0.2% β-glucan in the diet of rainbow trout improves growth performance, survival, haematological, immunity and biochemical parameters.

Antioxidant and immunostimulant responses in rainbow trout (Oncorhynchus mykiss) fed with cherry stem extract

We examined antioxidant enzyme activities, immune response, blood parameters and growth performance of rainbow trout fed with different doses of cherry stem (CS) aqueous methanolic extract. Four different feeds containing CS extract in different doses, 0% (control), 0.1 (0.1% CS), 0.5 (0.5% CS) and 1% (1% CS), as treatment feeds were prepared. Fish were fed with the diets for 60 days. The results showed that superoxide dismutase (SOD) activity was significantly increased on 20th and 60th days in all CS-treated fish groups. On 40th day, only 0.1% CS fish group had an elevated SOD activity compared with that of control (p < 0.05). Catalase (CAT) was significantly increased on 20th day of the study in 0.1 and 0.5 CS-treated groups compared with control and this increase was observed in all treatment groups on 40th day. However, in all fish groups, CAT was significantly decreased on 60th day. Glutathione peroxidase (GPx) was increased on 20th day in 0.1% CS fish group and in all treatment groups on the 60th day. G6PDH showed no significant difference at the end of experiment compared to the control. Similar result to that of G6PDH was obtained on lipid peroxidation. Haematocrit values of all the CS-treated fish groups were significantly increased at the end of the study. Growth did not differ among fish groups. Results indicated that 0.1% and 0.5% CS could be used as the dietary supplementation in rainbow trout.

Cytokine Gene Expression, Immune Responses and Disease Resistance of Oncorhynchus mykiss after Raphanus sativus By-products Supplementation

In the present study, we examined the effects of aqueous methanolic extract of radish seed (Raphanus sativus) by-products (RS) on innate immune responses and growth performance of rainbow trout (Oncorhynchus mykiss). The fish was fed diets containing 4 different doses of RS (0 % (Control), 0.1% (RS0.1), 0.5% (RS0.5) and 1% (RS1)) for 14 days. The results showed an increased activity of respiratory burst in fish of treatment groups compared to that of control on 14th day (P&lt;0.05). An enhanced bacterial killing activity was observed in R.05 and RS1 treatment groups compared to control (P&lt;0.05) on 7th day of the study. Lysozyme activity was elevated in fish of RS1 group on 7th day, and in all treatment groups on 14th day compared to that of the control. Myeloperoxidase activity increased significantly in RS1 and RS0.1 groups compared to the control on 7th day. IL-1b was up- regulated in head kidney of fish in RS0.1 group on 7th day and in RS0.5 group on 14th day of the study. In intestine of fish of experimental groups, IL-1b expression was significantly elevated on 7th day compared to the control. IL-12 was also up-regulated both in kidney and intestine of treatment group fish on 7th day. Similar results were observed on IL-10 expression. IL8 was up-regulated both in kidney and intestine of treated fish groups. Growth performance was affected positively in the RS1 group compared to the control. However, FCR value did not vary among different groups. Survival also improved against Aeromonas hydrophila infection in RS administered fish. All these results suggest that supplementation of RS through diets for 7 days could improve immune responses and growth in rainbow trout.