Dietary dl -methionyl- dl -methionine supplementation increased growth performance, antioxidant ability, the content of essential amino acids and improved the diversity of intestinal microbiota in Nile tilapia ( Oreochromis niloticus )

Heat inactive Bacillus subtilis var. natto regulate Nile tilapia (Oreochromis niloticus) intestine microbiota and metabolites involved in the intestine phagosome response

In this study, we evaluated the intestinal microbiota, intestinal and fecal metabolites production and the intestinal RNA-seq analysis of the Nile tilapia intestine after feeding with 10⁵and 10⁷ of the inactive Bacillus subtilis var. natto. First, we assessed the influence of heat inactive Bacillus subtilis var. natto on the growth performance, biochemical blood analysis, and evaluated the liver/body, spleen/body and intestine/body ratio. This evidence was known feeding with inactive Bacillus subtilis var. natto was able to improve the growth performance after 4 weeks, but not to affect the inflammatory biochemical blood parametres total protein (T-pro), albumin (Alb), Alb/T-pro ratio, creatine-phospho-kinase (CPK) and lactate dehydrogenase (LDH). Further, in the intestine microbiota, the Lactobacillaceae, Firmicutes, Chromatiales, and Rhodobacteria, was significantly higher than the control and the Firmicutes/Bacteroidetes ratio (F/B), which was indicated with a significantly increased. The intestine tissue metabolites OPLS-DA analysis indicated that the prominent bioactive metabolites changed. The peonidin-3-glucoside, l-Tyrosine, 1-Deoxy-1-(N6-lysino)-d-fructose was significantly increased. The feces metabolite OPLS-DA analysis indicated that the palmitelaidic acid, 5-KETE, tangeritin was significantly increased. In the transcriptome, the Gene Ontology (GO) analysis was found to enhance the intestine intestinal immune network. Combine of these evidence, feeding of the heat inactive Bacillus subtilis var. natto exactly improved the O. niloticus growth performance and regulation of the microbiota to promote the metabolites. In the transcriptome analysis, it was found to involve in the intestine immune phagosome response. Summarized of this study, the heat inactive Bacillus subtilis var. natto was reported to affect Nile tilapia intestine microbiota, and could positively regulate the intestine and fecal metabolites production to improve the intestine immune network.

Dietary Use of Methionine Sources and Bacillus amyloliquefaciens CECT 5940 Influences Growth Performance, Hepatopancreatic Histology, Digestion, Immunity, and Digestive Microbiota of Litopenaeus vannamei Fed Reduced Fishmeal Diets

An 8-week feeding trial investigated the effect of Fishmeal (FM) replacement by soybean meal (SBM) and poultry by-product meal (PBM) in diets supplemented with DL-Met, MET-MET (AQUAVI®), Bacillus amyloliquefaciens CECT 5940 (ECOBIOL®) and their combinations on growth performance and health of juvenile Litopenaeus vannamei. A total of six experimental diets were formulated according to L. vannamei nutritional requirements. A total of 480 shrimp (0.30 ± 0.04 g) were randomly distributed into 24 tanks (4 repetitions/each diet, 20 shrimp/tank). Shrimp were fed with control diet (CD; 200 g/Kg fishmeal) and five diets with 50% FM replacement supplemented with different methionine sources, probiotic (B. amyloliquefaciens CECT 5940) and their combinations: D1 (0.13% DL-MET), D2 (0.06% MET-MET), D3 (0.19% MET-MET), D4 (0.13% DL-MET plus 0.10% B. amyloliquefaciens CECT 5940 and D5 (0.06% MET-MET plus 0.10% B. amyloliquefaciens CECT 5940). Shrimp fed D3 and D5 had significantly higher final, weekly weight gain, and final biomass compared to shrimp fed CD (p < 0.05). Shrimp fed D2 to D5 increased the hepatopancreas epithelial cell height (p < 0.05). Digestive enzymatic activities were significantly increased in shrimp hepatopancreas’ fed D3 (p < 0.05). Meanwhile, shrimp fed D1 had significant downregulation of immune-related genes (p < 0.05). Moreover, shrimp fed D3 and D5 increased the abundance of beneficial prokaryotic microorganisms such as Pseudoalteromonas and Demequina related to carbohydrate metabolism and immune stimulation. Also, shrimp fed D3 and D5 increased the abundance of beneficial eukaryotic microorganism as Aurantiochytrium and Aplanochytrium were related to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) production which plays a role in growth promoting or boosting the immunity of aquatic organisms. Therefore, fishmeal could be partially substituted up to 50% by SBM and PBM in diets supplemented with 0.19% MET-MET (AQUAVI®) or 0.06% MET-MET (AQUAVI®) plus 0.10% B. amyloliquefaciens CECT 5940 (ECOBIOL®) and improve the productive performance, health, and immunity of white shrimp. Further research is necessary to investigate synergistic effects of amino acids and probiotics in farmed shrimp diets, as well as to evaluate how SBM and PBM influence the fatty acid composition of reduced fishmeal diets and shrimp muscle quality. Nevertheless, this information could be interesting to develop low fishmeal feeds for aquaculture without affecting the growth and welfare of aquatic organisms.

Methionine played a positive role in improving the intestinal digestion capacity, anti-inflammatory reaction and oxidation resistance of grass carp, Ctenopharyngodon idella, fry

A study was carried out to appraisal the function of methionine on intestinal digestion and the health of grass carp (Ctenopharyngodon idella) fry (initial weight 0.36 ± 0.01 g). The fry were fed graded dietary methionine levels (0.33%-1.20% dry matter) in 18 recirculatory tanks (180 L). After an 8-week breeding experiment, the results revealed that 0.71%-1.20% dietary methionine levels markedly upregulated the mRNA levels of intestinal digestion including trypsin, amylase, chymotrypsin and AKP, and 0.71%-0.87% dietary methionine level significantly increased intestinal trypsin activities compared with the 0.33% dietary methionine level. For inflammation, 0.71%-1.20% dietary methionine levels downregulated the mRNA levels of NF-κBp65, IL-1β, IL-6, IL-8, IL-15 and IL-17D, whereas upregulated the mRNA levels of anti-inflammatory cytokines, including IL-4/13B, IL-10 and IL-11. In terms of antioxidants, although dietary methionine levels had no significant effect on the expression of most core genes of the Nrf2/ARE signaling pathway, such as Nrf2, Keap 1, GPx4, CAT, Cu/Zn-SOD. Furthermore, dietary methionine levels had no significant effect on the expression of p38MAPK, IL-12p35, TGF-β2 and IL-4/13A. 0.71%-1.20% dietary methionine levels still increased the mRNA levels of GPx1α, GSTR and GSTP1. Furthermore, higher intestinal catalase activity and glutathione contents were also observed in fry fed 0.71%-1.20% diets. In summary, 0.71%-1.20% dietary methionine levels played a positive role in improving the intestinal digestion capacity of digestion, anti-inflammatory reaction and oxidation resistance of grass carp fry. This study provided a theoretical basis for improving the survival rate and growth of grass carp fry.

Optimal DL-Methionyl-DL-Methionine Supplementation Improved Intestinal Physical Barrier Function by Changing Antioxidant Capacity, Apoptosis and Tight Junction Proteins in the Intestine of Juvenile Grass Carp (Ctenopharyngodon idella)

The present study was a part of a larger research project that aimed to investigate the effects of Met-Met supplementation on fish growth and intestinal health. This study mainly focused on the relationship between dietary Met-Met and intestinal physical barrier function in fish. Seven iso-nitrogenous diets supplemented with 2.50 g/kg DL-methionine (DL-Met) and six graded levels of Met-Met (0.00, 0.79, 1.44, 1.84, 2.22, and 2.85 g/kg) were used to feed juvenile grass carp for 10 weeks, after which a 14-day Aeromonas hydrophila challenge test was performed. The results indicated that optimum levels of Met-Met decreased intestinal oxidative damage, probably by increasing total antioxidant capacity, and the activity and gene expression levels of several antioxidant enzymes, which were closely related to the changed Nrf2/Keap1 signaling. Meanwhile, optimum levels of Met-Met decreased intestinal apoptosis and improved the intestinal tight junction, as evident by the downregulated mRNA levels of initiator and executioner caspases; the pro-apoptotic-related proteins FasL, Apaf-1, and Bax; and upregulated mRNA levels of the anti-apoptotic proteins Bcl-2, Mcl-1b, and IAP and the TJ proteins claudins, occludin, and ZOs. Furthermore, the positive effects of Met-Met on improving intestinal physical barrier function were superior to those of DL-Met in fish. These findings showed that optimal Met-Met supplementation improved intestinal physical barrier function, probably by changing antioxidant capacity, apoptosis, and tight junction proteins in fish.

Adequate levels of dietary sulphur amino acids impart improved liver and gut health in juvenile yellowtail kingfish (Seriola lalandi)

The sulphur amino acids methionine (Met) and cysteine (Cys) and their derivative taurine (Tau) are metabolically active molecules with interlinked roles in nutritional requirements. Deficiencies in these nutrients are linked to poor growth and health; however, the impacts of these deficiencies on organ structure and function are largely unknown. This study examined the effects of dietary Met, Cys and Tau fed at different levels on yellowtail kingfish (YTK) liver histology and surface colour, plasma biochemistry and posterior intestine histology. Samples were collected from two dose-response feeding trials that quantified (1) the Tau requirement and sparing effect of Met by feeding YTK diets containing one of seven levels of Tau at one of two levels of Met and (2) the Met requirement and sparing effect of Cys by feeding YTK diets containing one of five levels of Met at one of two levels of Cys. YTK fed inadequate levels of dietary Met, Cys and Tau exhibited thicker bile ducts, less red livers, more intestinal acidic goblet cell mucus and supranuclear vacuoles and less posterior intestinal absorptive surface area. Further, thicker bile ducts correlated with less red livers (a*, R), whereas increased hepatic fat correlated with a liver yellowing (b*). Our results indicate a shift towards histological properties and functions indicative of improved intrahepatic biliary condition, posterior intestinal nutrient absorption and homoeostasis of YTK fed adequate amounts of Met, Cys and Tau. These findings may assist in formulating aquafeed for optimised gastrointestinal and liver functions and maintaining good health in YTK.

How Different Dietary Methionine Sources Could Modulate the Hepatic Metabolism in Rainbow Trout?

In aquafeeds in which plant proteins are used to replace fishmeal, exogenous methionine (Met) sources are demanded to balance the amino acid composition of diets and meet the metabolic fish requirements. Nonetheless, since different synthetic Met sources are commercially available, it is important to determine their bioavailability and efficacy. To address this issue, we conducted a two-month feeding trial with rainbow trout (Oncorhynchus mykiss), which were fed diets supplemented with five different forms of Met: Met-Met, L-Met, HMTBa, DL-Met, and Co DL-Met. No differences in growth performance were found in trout fed with different Met forms, but changes in the whole-body composition were found. In particular, Met-Met and L-Met promoted a significant body lipid reduction, whereas the protein retention was significantly increased in fish fed with HMTBa and Co DL-Met. The latter affected the hepatic Met metabolism promoting the trans-sulfuration pathway through the upregulation of CBS gene expression. Similarly, the L-Met enhanced the remethylation pathway through an increase in BHMT gene expression to maintain the cellular demand for Met. Altogether, our findings suggest an optimal dietary intake of all tested Met sources with similar promoting effects on fish growth and hepatic Met metabolism. Nevertheless, the mechanisms underlying these effects warrant further investigation.

Transformation of fish waste protein to Hermetia illucens protein improves the efficacy of poultry by-products in the culture of juvenile barramundi, Lates calcarifer

Promoting a circular economy via the transformation of food waste into alternative and high-value protein sources for aquaculture diets is a novel approach to developing alternative raw materials to fishmeal (FM). This approach can reduce the ecological impact on the aquatic environment and simultaneously can provide an option for sustainable food waste management. In this context, we report a 56-day trial of feeding barramundi, Lates calcarifer on four iso‑nitrogenous and iso-lipidic diets where the control (0PBM-0HI) was a FM-based diet and the other test diets replaced FM protein with mixtures of a poultry by-product meal (PBM) and a full-fat Hermetia illucens (HI) larvae meal reared on fish waste: the test diets were 85% PBM + 15% HI (85PBM-15HI), 80% PBM + 20% HI (80PBM-20HI) and 75% PBM + 25% HI (75PBM-25HI). Fish fed PBM-HI-based diets showed an equal growth rate and amino acid profile when compared to the control group. Among all serum metabolites, alanine aminotransferase and glutamate dehydrogenase decreased in fish fed PBM-HI-based diets, whilst total protein levels improved in the same diets. Serum lysozyme and bactericidal activity were unchanged which supported the observation of similar infection rates against V. harveyi. Except for the kidney and intestine, catalase activity in the serum and liver increased in fish-fed PBM-HI-based diets. In assessing the gastrointestinal mucosal morphology, the goblet cells producing neutral mucins were higher in PBM-HI-fed fish than the control. PBM-HI diets also enhanced bacterial richness and diversity and increased abundance for Lactobacillus, Clostridium, and Ruminococcus. In summary, combining full-fat HI with PBM allowed complete replacement of FM with no negative effects on growth whilst improving gut health. Such diets would be beneficial for the aquaculture industry, both ecologically and economically, as well as providing value-adding to animal waste as alternative protein sources for aquafeed production.

Structure and spectroscopy of methionyl-methionine for aquaculture

The amino acid L-methionine is an essential amino acid and is commonly used as a feed supplement in terrestrial animals. It is less suitable for marine organisms because it is readily excreted. It is also highly water soluble and this results in loss of the feed and eutrophication of the water. To address these problems, the dipeptide DL-methionyl-DL-methionine (trade name: AQUAVI Met-Met) has been developed as a dedicated methionine source for aquaculture. The commercial product is a mixture of a racemic crystal form of D-methionyl-D-methionine/L-methionyl-L-methionine and a racemic crystal form of D-methionyl-L-methionine/L-methionyl-D-methionine. In this work, we have computationally, structurally, spectroscopically and by electron microscopy characterised these materials. The microscopy and spectroscopy demonstrate that there is no interaction between the DD-LL and DL-LD racemates on any length scale from the macroscopic to the nanoscale.

Dietary supplementation of tilapia juveniles reared in bft (bioflocs) tanks with dl-methionine

Abstract The present study aimed at determining the effects of dietary DL-methionine supplementation on the water quality, bioflocs composition and Nile tilapia juvenile’s (initial body weight = 2.76 ± 0.06 g) growth performance in BFT rearing tanks (18 fish/100-L tank). Fish were or not subjected to artificial feed restriction. The experimental treatments consisted of two control groups: 1 - no feed restriction, no methionine supplementation; 2 - feed restriction at 25%, no methionine supplementation. There were also four treated groups: 1 - feed restriction at 25%, dietary DL-methionine supplementation at 0.5%; 2 - feed restriction at 25%, dietary DL-methionine supplementation at 1.0%; 3 - feed restriction at 25%, dietary DL-methionine supplementation at 2.0%; 4 - feed restriction at 25%, DL-methionine supplementation of molasses at 1.0. Supplementation of the commercial diet with DL-methionine has not affected either the water quality of the BFT Nile tilapia rearing tanks or the proximate composition of the bioflocs. After 8 weeks, weight gain of fish reared in tanks with feed restriction and dietary DL-methionine supplementation at 1% or 2% has not differed (P>0.05) from the tanks without feed restriction. In conclusion, it is possible to restrict the daily feed allowances of Nile tilapia juveniles reared in BFT tanks at 25%, with no growth performance impairment, if a minimal dietary DL-methionine supplementation of 1.0% is given.