Low Fish Meal Research Articles

Impact of dietary lysine on growth, nutrient utilization, and intestinal health in triploid rainbow trout (Oncorhynchus mykiss) fed low fish meal diets

Lysine is one of the essential amino acids for fish growth and development. This study investigated the effect of dietary lysine on growth performance, digestion, and intestinal health of triploid rainbow trout (Oncorhynchus mykiss) (initial body weight: 9.00 ± 0.33 g) fed a low fish meal diet (15 %). Five dietary lysine levels (3.66 %, 3.84 %, 4.19 %, 4.32 %, and 4.55 %) were evaluated for 56 days, with three replicates of 30 fish per level. The results showed that the weight gain rate (198.55 %), specific growth rate (1.95), and VSI were maximized when the dietary lysine level was 4.19 %. The 4.19 % lysine group exhibited minimum moisture (66.66 %) and maximum crude protein (15.47 %), with no significant differences in crude lipid and ash contents. Growth factors mTOR and 4EBP-1, on the other hand, had the highest expression in the 4.19 % group, while IGF-1 and S6K1 peaked in the 4.32 % group. The anti-inflammatory factors TGF-β, NF-κB, IL-4, and IL-10 peaked at different levels and then decreased with increasing lysine levels. The pro-inflammatory factor IL-1β, on the other hand, had the lowest expression at the 4.19 % level. Based on quadratic regression analysis of specific growth rate, the lysine requirement of triploid O. mykiss in low fish meal diets was 4.24 %.

Effects of hydroxyproline supplementation in low fish meal diet on growth, immunity and intestinal health of Litopenaeus vannamei

This experiment investigated the impacts of hydroxyproline (Hyp) supplementation in low fish meal diets on growth, antioxidant capacity, immunity and intestinal health of Litopenaeus vannamei. Six diets were formulated for the experiment, with the high fish meal diet containing 25 % fish meal (HF) and the remaining diets incorporating a mixture of soybean protein concentrate (SPC) and Clostridium autoethanogenum protein (CAP) replacing 15 % fish meal. These diets were supplemented with varying levels of Hyp (0 %, 0.2 %, 0.4 %, 0.6 %, and 0.8 %, designated as LF, H1, H2, H3, and H4, respectively). A total of 960 healthy shrimp (0.32±0.00 g) were divided into 6 groups at random; each group had 4 duplicates, each containing 40 shrimp. The shrimp were fed four times a day for a period of 51 days. The results indicated that dietary Hyp supplementation had no significant effects on growth performance and whole body composition of L. vannamei (P > 0.05). The antioxidant enzyme activities of hemolymph and hepatopancreas were significantly decreased after fish meal was replaced, and were significantly increased after dietary Hyp supplementation (P < 0.05). The expression of antioxidant-related genes in intestinal and hepatopancreas was significantly increased after dietary Hyp supplementation (P < 0.05). In the intestine, the gene expression of penaeidins 3 (pen3), dorsal, anti-lipopolysaccharide factor (alf) and crustins (cru) in the H2 group is the highest, and the gene expression of B-cell lymphoma-2 (bcl2) in the H3 group is the highest (P < 0.05). The genes expression of tumor necrosis factor-alpha (tnf-a), Bcl-2-assoxicated x protein (bax) and cytochrome c (cyc-t) in LF group reached the maximum (P < 0.05). Intestinal H&E stained sections showed that low-fish meal diet reduced the mucosal folds height of shrimp, and H2 and H3 groups significantly increased the mucosal fold height of shrimp (P < 0.05). Therefore, adding Hyp to the diet can improve the antioxidant capacity, immunity and intestinal health of L. vannamei.

Manipulation impacts of jack mackerel meal in low fish meal diets on growth, feed availability, and biochemical composition of olive flounder (Paralichthys olivaceus) and economic analysis

AbstractManipulation effects of jack mackerel meal (JMM) in the low fish meal (FM) diets substituting 50% FM with meat meal (MM) on growth performance of olive flounder and economic analysis were determined. Seven experimental diets were created. The control (Con) diet contained 60% FM. In the other diets, 50% of the FM level used for the Con diet was substituted with MM, and then graded levels (0, 10, 20, 30, 40, and 50%) of JMM were included at the expense of FM, named the MJ0, MJ10, MJ20, MJ30, MJ40, and MJ50 diets, respectively. The experimental diets were distributed to triplicate groups of fish. A total of 525 fish was divided into 21 flow‐through tanks. Fish were hand‐fed to apparent satiation for 8 weeks. Weight gain, specific growth rate (SGR), and feed consumption of fish fed the Con diet were comparable with fish fed the MJ20, MJ30, MJ40, and MJ50 diets. Weight gain, SGR, and feed consumption of fish linearly improved with JMM inclusion levels in the low FM diets replacing 50% FM with MM. The strong correlation between isoleucine and lysine content among essential amino acids in the experimental diets versus weight gain, SGR, and feed consumption of olive flounder were observed. Dietary treatments did not influence feed utilization, chemical composition, and amino acid profiles of fish. Incorporated 20%–50% JMM as an effective feed attractant and enhancer in the low FM diets replacing 50% FM with MM achieved comparable weight gain, SGR, and feed consumption to fish fed a 60% FM‐based diet. Finally, the MJ50 diet led to the highest economic profit index (EPI) for farmers.

Evaluation of dietary yeast derived mannan oligosaccharide for pacific whiteleg shrimp Penaeus vannamei: Effects on growth performance, immune response, hepatopancreas morphology and resilience to infection against Vibrio parahaemolyticus

With trends towards low fishmeal and higher plant ingredient-based diets for shrimp, there is consequently greater demand on feed additives to bolster the protein and nutrient profile quality for achieving more efficiency. Also, there is a need to enhance innate immunity and resilience to infection under intensive shrimp production scenarios. This investigation tested incremental levels 0, 0.2; 0.4; 0.6 and 0.8 % of a commercial yeast cell wall extract mainly comprising β-glucan and mannan oligosaccharides (MOS) (YM, YeaMOS, Angel Yeast, Yichang, Hubei, China) for post-larval shrimp Penaeus vannamei in isonitrogenous and iso-lipidic diets with proteinaceous plant ingredients amounting to 50 % contribution of the diet formulation. After 60 d, growth and feed utilization performance were not significantly affected in shrimp in terms of weight gain or FCR, but due to much higher survival, total biomass in groups of shrimps fed with dietary YM was higher compared to the control treatment. A sequential specific pathogen challenge test with Vibrio parahaemolyticus at final dose of 104 CFU mL−1 resulted in a marked improvement in survival against the control group with much enhancement at the inclusion level of 0.4 % YM (p<0.05). Before challenged, the total haemocyte count (THC) and the relative gene expression of Prophenoloxidase (ProPO) were higher in the group of shrimps fed with YM. Likewise, after infection, the amount of THC and ProPO remained better in the group of shrimps fed with YM. However, the 0.8 % YM treatment did not significantly differ from the control for phagocytic activity and index. The histomorphology condition of the hepatopancreas of shrimp before the infection for all treatments appears normal without significant numbers of hepatopancreatic tubules (T) and epithelial cell vacuoles (V). After pathogen challenge, all shrimp exhibited severe necrotic cell damage and massive sloughing of hepatopancreatic tubule epithelial cells into the lumen. Overall, giving YM as feed additives can improve the shrimp biomass and health, with the use of 0.4 % inclusion levels in practical diets for shrimp P. vannamei become the optimum dose to develop more efficient aquafeed production.

Automated phenotyping empowered by deep learning for genomic prediction of body size in the tiger pufferfish, Takifugu rubripes

Although genomic selection (GS) is accelerating the genetic improvement of economically important traits in aquaculture species, the accurate phenotyping of thousands of individuals remains a bottleneck in GS programs. Computer vision (CV) technologies with the assistance of deep learning may provide a cost-efficient solution for automated phenotyping of fish body size. In this study, we designed a CV-based automated phenotyping system based on the deep learning model Mask R-CNN (region-based convolutional neural networks) and tested its ability to predict standard length (SL) of tiger pufferfish (Takifugu rubripes) fed low fishmeal (LFM) diet. Simultaneously, we investigated the impact of the automated phenotyping on genetic parameter estimation and genomic prediction for growth-related traits. We raised a test population (n = 1001) that was fed the LFM diet from three months old until harvest at 22 months. Manual phenotyping of the fish was performed at 10-, 14-, 17-, and 22-months-old. At the last two measurement times, images of each fish were collected to train Mask R-CNN for fish detection and pixel-level segmentation of the fish body excluding the tail fin. An automated phenotyping pipeline combining the trained Mask R-CNN and standard CV algorithms were designed to estimate SL. We found a high correlation (0.965–0.971) and low relative difference (0.015–0.027) between the CV-derived and manually measured SL, indicating high precision of our CV system. A high correlation (0.912–0.956) was also observed between CV-derived body area and manual body weight. The heritability estimations and genomic predictions on manual SLs were conducted using a Genomic Best Linear Unbiased Prediction (GBLUP) model using a total of 16,471 single nucleotide polymorphism (SNP). Estimated heritability at the four sampling points ranged from 0.573 to 0.622, and the predictive ability of genomic prediction for harvest size was 0.627. These values are comparable to those reported in previous studies collected from the population fed a normal fishmeal diet. Our heritability estimation and genomic prediction derived from automated SL measurements differed negligibly to those based on manual measurements. This finding indicates the utility of our CV-based automated phenotyping system for GS breeding programs.

Dietary Taurine Improves The Growth Performance, Health Status and Liver Histopathology of Meagre (Argyrosomus Regius) Fed A Reduced Fish Meal Diet

Abstract Research has focused on alternative plant materials or additives that can be used instead of fish meal due to limited stocks and increased feed prices, although it is important for carnivorous fish species. Taurine is a functional amino acid supplemented to low fish meal diets to improve the growth performance of fish. In this study, eight experimental diets with 0%, 0.5%, 1% and 2% ratios of taurine supplemented (T0, T0.5, T1 and T2) high (HFM) and low fish meal (LFM) diets were prepared (defined as HFMT0, HFMT0.5, HFMT1, HFMT2, LFMT0, LFMT0.5, LFMT1 and LFMT2). The experiment was carried out in twenty-four 400 L rectangular fiberglass tanks conducted in a marine water system, and fish (initial mean weight of 23.5 g) were stocked in each tank. The nutrition trial was carried out for 90 days with three replicates. Meagre fed with the HFMT1 diet had a higher final mean weight (FMW) and specific growth rate (SGR) than fish fed with HFMT0 and all LFM diets. Including taurine in all LFM diets also enhanced growth performance. The FMW and SGR of fish fed the LFMT0.5 diet were similar when compared to HFMT0 (P&gt;0.05) and increased compared to that of other LFM diets with taurine (P&lt;0.05). Meagre fed the LFM0.5 diet had a lower feed conversion rate (FCR) than those provided for all HFM diets, although there was no significant difference between treatments. Dietary taurine has decreased the hepatosomatic index (HSI), viscerosomatic index (VSI) and total ammonia-nitrogen excretion (TAN), irrespective of taurine and fish meal levels. Including dietary taurine at both fish meal levels enhances the number of red blood cells (RBC) and whole-body amino acids of meagre. The most remarkable conclusion of this study is the inclusion of taurine in low fish meal diets improved growth performance and profitability in meagre, and the level of 0.5% has been recommended.

Optimizing valine supplementation in low-fish meal diets for enhanced growth, digestion, antioxidant capacity, and intestinal health of triploid rainbow trout (Oncorhynchus mykiss)

This study evaluates the effects of valine on the growth, digestion, antioxidant capacity, and intestinal health of triploid rainbow trout (Oncorhynchus mykiss) fed a low fish meal diet (10 %). The trouts with an initial body weight of 15.08±0.20 g were fed with five different isonitrogenous and isoenergetic diets containing levels of valine: 0.86 % (G1), 1.79 % (G2), 2.43 % (G3), 3.02 % (G4), and 3.68 % (G5) for 56 days. The results showed that the weight growth rate and specific growth rate of the 2.43 % group were significantly higher than those of the 0.86 % control group (P<0.05). The intestinal villus length and muscle layer thickness propria were significantly increased in the 3.02 % group compared to the control group (P<0.05). The activities of intestinal protease, amylase, superoxide dismutase, catalase, and lysozyme in the 2.43 % group were significantly higher than those in the control group (P<0.05). The levels of interleukin-8 and tumor necrosis factor-alpha were lowest in the 3.02 % group, while the IL-10 level was highest in the 3.02 % group (P<0.05). Elevated levels of valine in the dietary regimen correlated positively with the upregulation of pivotal genes associated with antioxidant mechanisms, notably nuclear factor erythroid 2-related factor 2 (Nrf2), NAD(P)H: quinone oxidoreductase 1 (NQO1), and thioredoxin (Trx). Additionally, the expression of genes implicated in the synthesis of tight junction proteins, including occludin, claudin 7b, and claudin 15, exhibited significant augmentation with escalating valine concentrations in the feed. In conclusion, dietary valine enhanced the growth, digestive and absorptive capabilities, antioxidant capacity, and intestinal health of O. mykiss. An analysis based on a quadratic curve model, which incorporates specific rates of growth and weight gain, establishes that the optimal dietary valine requirement for triploid O. mykiss consuming a 10 % fish meal diet ranges between 2.43 % and 2.69 %.

Inclusion effect of jack mackerel meal in olive flounder (Paralichthys olivaceus) diet substituting blended fish meal with tuna by-product meal on growth, feed availability, and economic efficiency

The low fish meal (FM) diet commonly causes deteriorated palatability, and eventually leads to lowered feed consumption and growth performance of fish. This study was, therefore, designed to determine inclusion impact of the graded levels of jack mackerel meal (JMM) in olive flounder (P. olivaceus) diets replacing 50% FM with tuna by-product meal (TBM) on growth, feed availability, biochemical composition, blood chemistry, and economic efficiency. Six isonitrogenous (55.5%) and isolipidic (10.0%) diets were formulated. Sixty percent FM was incorporated in the control (Con) diet. In the Con diet, fifty percent of FM was replaced by TBM, and then 10, 20, 30, 40, and 50% JMM were included at the cost of FM, referred as the TJ10, TJ20, TJ30, TJ40, and TJ50 diets, respectively. Three hundred and sixty juvenile fish (18.0 ± 0.01g; mean ± SD) were delivered into 18, 50-L flow-through tanks. All diets were randomly assigned to triplicate groups of fish. Fish were hand-fed to apparent satiation twice daily for 56 days. Weight gain, specific growth rate, and feed consumption of fish fed the TJ30, TJ40, and TJ50 diets were significantly (P &amp;lt; 0.001, P &amp;lt; 0.001, and P &amp;lt; 0.002, respectively) greater than those of fish fed the Con and TJ10 diets, but not significantly (P &amp;gt; 0.05) different from those of fish fed the TJ20 diet. Feed utilization, proximate composition, amino acid profiles, and blood chemistry of fish were not significantly (P &amp;gt; 0.05) altered by dietary treatments. However, the TJ30 diet was the most recommendable to farmers in terms of economic profit index (EPI). Conclusively, 30% inclusion of JMM is the most recommendable in the olive flounder diet substituting 50% FM with TBM based on growth performance, feed availability, and EPI.

Medium-short chain fatty acids cannot spare the essential fatty acids of low marine diets in golden pompano (Trachinotus ovatus)

Based on the essential fatty acids (EFA) precision nutrition, a blend oil (BO) of fish oil and terrestrial oils was developed, and applied successfully to the low marine diets of golden pompano (Trachinotus ovatus). To evaluate whether medium- and short-chain fatty acids (MCFA and SCFA), efficient energy supplements for animals, can spare the dietary EFA, four iso-proteic (48%) and iso-lipidic (11%) low fishmeal (FM) diets (D1-D4, contained 6% FM) were formulated and fed T. ovatus juveniles (initial weight ∼8.50 g) for 9 weeks in sea cages. Control diets (D1) contained 8% BO, while the BO of diets D2-D4 were replaced 50% with coconut oil, coconut oil + sodium butyrate, and coconut oil + n-3 LC-PUFA enriched oil, respectively. The results showed that compared to the D1 group, the growth performance of D2 and D3 were significantly lower, while a comparable growth was detected in the D4 group. The muscle and hepatic n-3 PUFA levels in the D2 and D3 groups were significantly low, and these fatty acid contents were modified in the D4 group. Meanwhile, the muscle textural firmness of the D2-D4 groups was decreased. Regarding the health index of fish, compared to the D1 group, high serum triglyceride (TG) contents and low HDL/LDL ratio were detected in the D2-D4 groups, and high ACP, AST, and ALT activities were observed in these groups. Meanwhile, high HSI and low hepatic enzymatic activities of CAT and ALT were measured in the D2-D3 groups. Additionally, the mRNA levels of hepatic fatty acid synthesis-related genes (fas, acc, and pparγ) were significantly increased in D2-D4 groups, and the expression levels of lipid catabolism genes (cpt-1 and lpl) showed an upward trend. Moreover, the D2 group exhibited the lowest intestinal wall thickness, the mRNA levels of intestine anti-inflammatory cytokines (il-10) were up-regulated in the D2-D4 groups, and the highest mRNA levels of pro-inflammatory cytokines (il-8) were detected in the D2 group. In conclusion, the EFA deficiency leads to a decline in the growth and muscle quality of T. ovatus fed low marine diets, which cannot be mitigated by the addition of medium-short chain fatty acids. The results indicated that MCFA and SCFA cannot spare the EFA of low marine diets in T. ovatus.

Heritability and predictive ability for the heterobothriosis resistance and growth performance in the tiger pufferfish Takifugu rubripes fed standard or low fishmeal diets

Heterobothriosis resistance and high growth performance are major concerns in the tiger pufferfish (Takifugu rubripes) farming. Our previous small-scale study suggested the feasibility of genomic selection (GS) for these traits but also identified an undesired genetic correlation between them, which could hamper simultaneous genetic improvement. Here, we sought to validate these initial findings through larger samples and crosses and also explore the potential of GS for the individuals fed a normal fishmeal diet and a low fishmeal (LFM) diet. We produced three populations: one was fed a normal diet (PopFM: 1100 individuals) and two were fed an LFM diet (PopLFM1: 993 individuals; PopLFM2: 1017 individuals); all three populations were artificially infected with Heterobothrium okamotoi, a monogenean parasite causing heterobothriosis. We recorded standard lengths of the fish after artificial infection (SLEAI) and the number of parasites on the gill cavity wall (HC) and genotyped genome-wide single nucleotide polymorphisms (SNPs) using genotyping by random amplicon sequencing, direct (GRAS-Di) technology for each sample: PopFM, 12 K SNPs; PopLFM1, 19 K SNPs; PopLFM2, 21 K SNPs. Heritability and prediction ability for each trait were estimated for each population using genomic best linear unbiased prediction (GBLUP), Bayes C, and Bayesian ridge regression methods. SNP effects on each trait were estimated by Bayes C, Bayesian ridge regression, and genome-wide association analyses (GWAS) using the same data sets. We observed moderate to high levels of heritability for HC (0.16–0.57) and SLEAI (0.50–0.77), with predictive ability of 0.25–0.55 for HC and of 0.51–0.73 for SLEAI. These values were slightly larger in LFM diet groups. As reported previously, a weak undesired genetic correlation was observed between the traits, and the correlation was more pronounced in the LFM groups. In conclusion, our results indicate that genetic gain in growth and parasite resistance traits can be expected for the tiger pufferfish through GS, especially for individuals reared on an LFM diet. However, close attention should be paid to the extent of the undesirable genetic correlation between the two traits that may be amplified in the populations fed an LFM diet.

Sodium butyrate supplementation in two-level fishmeal diets for rainbow trout (Oncorhynchus mykiss): growth performance, immunological responses, and intestinal investigation

Abstract The dietary effect of sodium butyrate, Butirex®C4 (NaBT), on some physiological and immunological responses, as well as carcass and fillet quality were studied in rainbow trout, Oncorhynchus mykiss (initial body weight, 16.63±0.10 g; mean ± SE) fed two-level fishmeal (FM) diets. Six experimental diets were formulated to include two levels of FM (15% and 30%) and supplemented with incremental levels of NaBT (0%, 0.25%, and 0.5%). An improvement in growth performance was obtained in fish fed diet containing 0.5% NaBT+30% FM. Dietary NaBT inclusion significantly increased the digestive enzyme activity of fish compared to those without a NaBT diet. The highest immune parameters for mucus and serum were observed in fish fed with 0.25% NaBT+30% FM and 0% NaBT+30% FM diets, respectively. Fish fed diets containing 0.5% NaBT+15% FM and 0.25% NaBT+30% FM had significantly higher antioxidant enzymes activity (superoxide dismutase (SOD) and glutathione peroxidase activity (GPx)) in comparison to other groups. At selected NaBT levels, fish fed with FM (15% and 30%) showed higher bactericidal activity in comparison to group fed diet without NaBT supplementation. Based on the results of the intestine microflora, the highest gastrointestinal tract (GIT) total count and GIT lactic acid count were observed in groups included with 0% NaBT+15% FM and 0.5% NaBT+30% FM. Fish fed diets containing 0.5% NaBT+15% and 30% FM showed improvement in fillet quality in comparison to other groups. In conclusion, dietary NaBT supplementation, especially at the inclusion level of 0.5%, can improve physiological and immunological responses and reduce the adverse effects of the diets with the lower FM in rainbow trout.

Evaluation of the use of commercial-type and synthetic diets to test a nucleotide-rich yeast-derived product as a growth promotor for first feeding rainbow trout fry raised at 10 or 16 °C

A nucleotide-rich yeast-derived product (Maxi-Gen™; CBS Bio Platforms, Inc., Calgary AB, Canada), was fed to rainbow trout fry housed at 10 or 16 °C to determine its effect on weight gain and feed intake. Rainbow trout fry housed in 40 16 L tanks (25 fish/tank) were fed commercial-type or synthetic diets with or without the nucleotide-rich yeast product added (0% or 0.5% inclusion) until they reached 60 days of age (5 tanks/4 diets/2 temperatures). Fish housed at 16 °C consumed significantly more feed and gained significantly more weight than fish housed at 10 °C. Trout fed the commercial-type diet gained significantly more weight than those fed the synthetic diet without the nucleotide-rich yeast product added. There was no significant difference in weight gain or feed intake among fish fed either commercial-type diet and the fish fed the synthetic diets with the nucleotide-rich yeast product added, although fish fed the commercial-type diets had significantly better feed conversion efficiencies than those fed the synthetic diets. The nucleotide-rich yeast product could be used in low fish meal, low fish oil first feeding diets, as the aquaculture industry decreases fish meal and oil use in aquafeeds in response to their increasing cost and decreasing availability.

DL-Methionyl-DL-Methionine/DL-Methionine Supplementation Alleviated the Adverse Effects of Dietary Low Fishmeal Levels on Growth and Intestinal Health of Micropterus salmoides.

DL-methionyl-DL-methionine (AQUAVI® Met-Met) (Met-Met) (0.10%, 0.20%, 0.30%, and 0.40%) or DL-methionine (DL-Met) (0.10%, 0.20%, 0.30%, and 0.40%) were added to a low-fishmeal diet in an attempt to reduce fishmeal in the diet of Micropterus salmoides (M. salmoides). The fish were randomly allocated into ten experimental groups (n = 100), each with 4 replicates of 25 fish (16.39 ± 0.01 g) each. Compared to 25% FM, 0.40% of DL-Met and 0.10% of Met-Met promoted growth, and 0.10% of Met-Met decreased FCR. Compared to 25% FM, the supplementation of Met-Met or DL-Met improved the intestinal antioxidant capacity by upregulating the NF-E2-related factor 2-mediated antioxidant factors and enzyme activities and nuclear factor kappa-B-mediated anti-inflammatory factors while downregulating the pro-inflammatory factors, thereby exerting anti-inflammatory effects. Moreover, 0.10% of the Met-Met diet affected the Firmicutes-to-Bacteroidota ratio, increased the levels of Proteobacteria, changed the composition of intestinal flora (Roseburia, Lachnospiraceae_NK4A136_group, and unclassified_Oscillospiraceae), and enhanced intestinal dominant bacteria (Caldicoprobacter, Pseudogracilibacillus, and Parasutterella), leading to improved gut health. In summary, the supplementation of DL-Met or Met-Met alleviated the adverse effect of fishmeal reduction (from 40 to 25%) on the growth performance and intestinal health of M. salmoides.

Effects of Three Feed Additives in Low Fish Meal Diet on Growth, Antioxidant Capacity and Intestinal Microbiota of Penaeus monodon

The effects of three feed additives in a low fish meal diet on growth, antioxidant capacity and intestinal microbiota of Penaeus monodon were studied to enhance the understanding of these effects and to provide basic data and a reference for the formulation and optimization of feed for P. monodon. A total of 630 healthy, homogenous shrimp (4.58 ± 0.05 g) were randomly divided into seven groups with three replicates per group and 30 shrimp per replicate in a breeding barrel (500 L). The additive names and amounts were 0 (CT); vitamin B6, 100 mg/kg (V1); vitamin B6, 200 mg/kg (V2); phytase, 1000 U/kg (P1); phytase, 2000 U/kg (P2); 0.2% yucca extract (Y1); and 0.4% yucca extract (Y2). The experiment lasted 8 weeks. The results showed that compared to CT, V1 and Y1 had a significant increasing tendency toward weight gain (WG) (p &lt; 0.05) and had a significant decreasing tendency in the food conversion ratio (FCR) (p &lt; 0.05). P2 had a significant increasing tendency in α-amylase activity (p &lt; 0.05), and P1 had a significant increasing tendency in total superoxide dismutase (T-SOD) (p &lt; 0.05). The next-generation sequencing of intestinal microbiota showed that Proteobacteria was the most abundant phylum in the seven groups, accounting for 29.33%, 56.67%, 55%, 45.33%, 73%, 39.33% and 64.33% of the total. Compared to CT, the Proteobacteria was significantly high (p &lt; 0.05) in P2 and Y2, and the Bacteroidota in all other groups decreased significantly (p &lt; 0.05). The functional prediction of FAPROTAX indicated that there was no significant difference (p &gt; 0.05) in functional components among all groups. According to growth performance, antioxidant capacity and effects on intestinal microbiota, vitamin B6 (100 mg/kg), phytase (2000 U/kg) and yucca extract (0.2%) can be recommended as additives for the diet of P. monodon.

Substitution effect of fish meal with various plant protein sources on growth performance and feed utilization in rockfish (Sebastes schlegeli) diets including jack mackerel meal used as feed stimulants

Incorporating feed stimulants and attractants in low fish meal (FM) diets is a very effective way to improve palatability and increase feed intake and fish growth. This research aims to elucidate the substitution impact of different levels of FM with various plant proteins in diets with jack mackerel meal (JMM) inclusion as feed stimulants on the growth and feed utilization of rockfish (Sebastes schlegeli). A two-way (2 substitution levels [25% and 50%] × 3 substitution sources [corn gluten meal (CGM), soybean protein concentrate (SPC), and corn protein concentrate (CPC)]) ANOVA experimental design was adopted. In total, 525 fish averaging 8.3 g were assigned to 21 tanks (25 juvenile/tank). Seven isoprotetic and isolipidic feeds were formulated. The control (Con) diet contained 55% FM. CGM, SPC, and CPC were replaced for 25% and 50% FM in the Con diet, and then 22% JMM as feed stimulants was included at the cost of FM, named as the CGM25, CGM50, SPC25, SPC50, CPC25, and CPC50 diets, respectively. All diets were assigned to triplicate groups of rockfish. Rockfish were hand-fed to apparent satiation twice a day for 8 weeks. Rockfish fed the 25% FM substitution diets achieved superior (p &amp;lt; 0.0001 for both) weight gain and specific growth rate (SGR) compared to rockfish fed the 50% FM substitution diets, while rockfish fed the CGM-replaced diets achieved superior (p &amp;lt; 0.0001 for both) weight gain and SGR compared to rockfish fed the SPC- and CPC-replaced diets. The weight gain and SGR of rockfish fed the Con and CGM25 diets were superior to rockfish fed all other diets. Rockfish fed the 25% FM substitution diets achieved superior (p &amp;lt; 0.0001 for both) feed efficiency (FE) and protein efficiency ratio (PER) compared to rockfish fed the 50% FM substitution diets, while rockfish fed the CGM-replaced diets achieved superior FE and PER compared to rockfish fed the CPC-replaced diets. Rockfish fed the 25% FM substitution diets led to superior (p &amp;lt; 0.0001) protein retention (PR) compared to rockfish fed the 50% FM substitution diets. The biological indices, proximate composition, and amino acid profiles of the whole body, as well as the plasma and serum parameters of rockfish, were not changed by either substitution level or substitution source. In conclusion, the replacement of CGM for 25% FM in the rockfish diet with JMM inclusion can be made without deteriorating growth performance, feed consumption and utilization, biochemical composition, and plasma and serum parameters.

Yacon Juice Residue Supplementation in Low Fish Meal Diet for Black Rockfish (Sebastes schlegelii)

Yacon Juice Residue Supplementation in Low Fish Meal Diet for Black Rockfish (Sebastes schlegelii)

Roles of Dietary Supplementation of Exogenous Protease in Low Fishmeal Aquafeed − A Mini Review

Abstract The replacement of fishmeal (FM) with economical and nutritious FM alternatives including plant- and animal-based protein ingredients has become a global research priority. However, the presence of several anti-nutritional factors (ANFs) in these alternatives may impair nutrient utilization in fish. The supplementation of exogenous protease as feed additives could be an effective approach to improve the nutrient digestibility of these alternative proteins. Proteases are protein-digesting enzymes that catalyze the hydrolysis of complex protein macromolecules into simpler amino acids. Exogenous protease supplementation stimulates the activities of endogenous proteolytic enzymes for better nutrient digestion and absorption in fish. This review article summarizes the optimum protease supplementation levels in various fish species and its beneficial effects on growth performance, nutrient digestibility, intestinal morphology, digestive enzyme activities, whole-body composition, physiochemical parameters, immunity, and gene expression of fish. Moreover, the interactive effects of exogenous protease with organic acids and probiotics are also discussed. Overall, the supplementation of exogenous protease in fish feed is a viable solution for poor nutrient utilization of FM alternatives. Important gaps, however, exist in the current knowledge, particularly with regard to the effect of protease supplementation in animal-based proteins as most of the studies have focused on the effect of protease supplementation on plant-based proteins as FM alternatives. Moreover, additional studies focused on the effect of protease supplementation on the digestive enzyme activities, immunity, gut microbes and antioxidant parameters of fish will provide the basis for a better understanding of the mode of action of protease. The scarce knowledge in these areas limits the scope of protease supplementation as a feed additive in the aquaculture sector.

Effects of dietary enzymatically treated Artemisia annua L. in low fish meal diet on growth, antioxidation, metabolism and intestinal health of Micropterus salmoides

The excessive substitution of fish meal (FM) by Clostridium autoethanogenum protein (CAP) could reduce the growth performance and disrupt the intestinal structural integrity of Micropterus salmoides. In order to solve this problem, an eight-week feeding trial was conducted to investigate the effects of dietary enzymatically treated Artemisia annua L. (EA) in low FM diet containing high-CAP on growth, antioxidation capacity, lipid and carbohydrate metabolism and intestinal microbiota of M. salmoides. Six isonitrogenous and isolipid experimental diets were produced containing 0 g/kg, 0.25 g/kg, 0.5 g/kg, 1.0 g/kg, 2.0 g/kg and 4.0 g/kg of dietary EA, which were named EA0, EA0.25, EA0.5, EA1.0, EA2.0 and EA4.0, respectively. After the feeding trial, the weight gain rate (WGR) and specific growth rate (SGR) were significantly increased in EA0.25, EA0.5 and EA 1.0 groups compared to EA0 group. The digestive enzyme activities in stomach and intestine, and the villus width and muscular layer thickness of the intestine were increased by dietary EA. Dietary EA improved the antioxidation capacity and serum lipid level of M. salmoides. The expression levels of sterol regulatory element-binding protein 1-c (srebp1-c), acetyl-coa carboxylase alpha (accα), fatty acid synthase (fan), 3-hydroxy-3-methylglutaryl-coa reductase (hmgcr) and accβ were significantly upregulated by 4.0 g/kg of dietary EA. The mRNA level of peroxisome proliferator-activated receptor alpha (pparα) and carnitine palmitoyltransferase 1 (cpt-1) were upregulated by 4.0 g/kg and 0.5 g/kg of dietary EA, respectively. Besides, the glucose content in serum was decreased by EA. The expressions of forkhead box o1 (foxo1), phosphoenolpyruvate carboxykinase (pepck), fructose bisphosphatase (fbp), glucokinase (gk) and pyruvate kinase (pk) were significantly improved by 4.0 g/kg of dietary EA, and the level of phosphofructokinase (pfk) was upregulated by 0.5 g/kg of dietary EA. The addition of 0.5 g/kg of dietary EA could optimize beneficial Cetobacterium and reduce harmful Mycoplasmataceae abundances in intestine of M. salmoides. In summary, the appropriate amount of dietary EA could be added to the high-CAP diet to improve the growth performance, antioxidation, lipid and carbohydrate metabolism, liver and intestinal health of M. salmoides. This study will provide scientific guidance for replacing FM with non-food proteins.

Dietary effects of supplementing Clostridium butyricum culture or sodium butyrate in low fishmeal diet on growth, serum indicators, intestinal histology and microbiota of largemouth bass (Micropterus salmoides)

The present study aimed to evaluate the dietary effects of Clostridium butyricum culture (CC) or sodium butyrate (SB) on the growth, feed utilization, serum indicators, intestinal histology and microbiota of largemouth bass (Micropterus salmoides). CC and coated SB (50%) were supplemented to a low fish meal diet (245 g/kg) (control diet) at the inclusion levels of 1 g/kg and 2 g/kg, to form five iso-nitrogenous and iso-lipidic diets (control, CC-1, CC-2, SB-1, and SB-2). Then, the five diets were fed to largemouth bass with initial body weight of 70.2 ± 0.1 g. After 8 weeks of feeding, dietary supplementation of 1 g/kg CC increased the weight gain (WG) by 7.4% (P < 0.05), and decreased the feed conversion ratio by 0.09 (P < 0.05), while dietary SB just numerically improved the WG (P > 0.05), when compared to the control. The muscle composition was not significantly affected by the inclusion of CC or SB (P > 0.05). Dietary inclusion of CC or SB significantly reduced serum diamine oxidase activity and increased lysozyme activity (P < 0.05), while the decreased D-lactic acid level was observed only in the two SB groups (P < 0.05). In intestinal histology, the 1.0 g/kg CC group presented significantly higher intestinal villus height, width and muscle layer thickness than the control group (P < 0.05). The intestinal microbiota analysis showed that dietary CC or SB (1 g/kg) increased the abundance of Fusobacteriota and Cetobacterium, decreased the abundance of Proteobacteria and Aeromonas. In conclusion, the supplementation of CC in low fish meal diet promoted the growth performance, feed utilization, and both CC and SB supplementation positively modulated the intestinal microorganism community of largemouth bass.

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.