Plant Protein-based Diets Research Articles

Effect of inclusion of animal proteins to plant protein-based diet on physiological condition of red seabream Pagrus major

Effect of inclusion of animal proteins to plant protein-based diet on physiological condition of red seabream Pagrus major

Heat/non-heat treatment alleviates β-conglycinin-triggered food allergy reactions by modulating the Th1/Th2 immune balance in a BALB/c mouse model.

With the increasing popularity of plant protein-based diets, soy proteins are favored as the most important source of plant protein worldwide. However, potential food allergy risks limit their use in the food industry. This work aims to reveal the mechanism of β-conglycinin-induced food allergy, and to explore the regulatory mechanism of heat treatment and high hydrostatic pressure (HHP) treatment in a BALB/c mouse model. Our results showed that oral administration of β-conglycinin induced severe allergic symptoms in BALB/c mice, but these symptoms were effectively alleviated through heat treatment and HHP treatment. Moreover, β-conglycinin stimulated lymphocyte proliferation and differentiation; a large number of cytokines interleukin (IL)-4, IL-5, IL-10, IL-12 and IL-13 were released and interferon γ secretion was inhibited, which disrupted the Th1/Th2 immune balance and promoted the differentiation and proliferation of naive T cells into Th2-type cells. Heat/non-heat treatment altered the conformation of soybean protein, which significantly reduced allergic reactions in mice. This regulatory mechanism may be associated with Th1/Th2 immune balance. Our results provide data support for understanding the changes in allergenicity of soybean protein within the food industry. © 2024 Society of Chemical Industry.

Gut microbiota-bile acid crosstalk and metabolic fatty liver in spotted seabass (Lateolabrax maculatus): The role of a cholesterol, taurine and glycine supplement

The prevalent practice of substituting fishmeal with plant protein frequently leads to disturbances in bile acid metabolism, subsequently increasing the incidence of metabolic liver diseases. Bile acid nutrients such as cholesterol, taurine and glycine have been shown to enhance bile acid synthesis and confer beneficial effects on growth. Therefore, this study aimed to investigate the effects of cholesterol-taurine-glycine (Ch-Tau-Gly) supplement on bile acid metabolism and liver health in spotted seabass (Lateolabrax maculatus) fed a plant-based diet. Two isonitrogenous and isolipidic diets were formulated: (1) plant protein-based diet (PP); (2) PP supplemented 0.5% cholesterol, 0.5% taurine and 1.3% glycine (CTG). Each experimental diet was randomly fed to quadruplicate groups of 30 feed-trained spotted seabass in each tank. The results revealed that supplementing plant-based diet with Ch-Tau-Gly supplement led to an increase in carcass ratio (meat yield) in spotted seabass (P < 0.05), indirectly contributing positively to their growth. The dietary supplement effectively suppressed endogenous cholesterol synthesis in the liver, promoted the expression of bile acid synthesis enzyme synthesis, and simultaneously the expression of intestinal fxr and its downstream genes, including hnf4α and shp (P < 0.05). The reduction in Lactobacillus_salivarius and bile salt hydrolase (BSH) were observed in CTG group with concurrently increased conjugated chenodeoxycholic acid (CDCA) bile acids (P < 0.05), suggesting the enhancement of the hydrophilicity of the bile acid pool. In CTG group, fatty liver was alleviated with a corresponding increase in lipid metabolism, characterized by a downregulation of genes associated with lipogenesis and lipid droplet deposition, along with an upregulation of genes related to lipolysis. Our study underscored the ability of Ch-Tau-Gly supplement to influence the gut microbiota, leading to an increase in the levels of conjugated CDCA (P < 0.05) in the bile acid pool of spotted seabass. The interplay between the gut microbiota and bile acids might constitute a crucial pathway in the promotion of liver health. These findings offer a promising solution, suggesting that Ch-Tau-Gly supplement have the potential to promote the growth of aquatic species and livestock fed on plant-based diets while addressing issues related to metabolic fatty liver.

Meat and carcass quality of weaner rabbits placed on three different plant protein-based diets

The study assessed the effect of replacing groundnut cake (GNC) with palm kernel cake (PKC) or cotton seed cake (CSC) on the meat and carcass characteristics of rabbits. Sixty mixed breed weaner rabbits of both sexes with an age range of eight to nine weeks old were randomly divided into three treatments 1, 2, and 3 of 20 rabbits per group. Rabbits in the group one (T1) served as the positive control and were fed GNC-based diet, while those in treatments two (T2) and three (T3) were fed PKC-, and CSC-based diets respectively. The results differed non-significantly (p&gt;0.05) in the final body weight and carcass quality of the rabbits in each group. Carcass evaluation varied non-significantly (p&gt;0.05) in terms of visceral (liver, lungs, hearts, and kidneys) and weights of primal cuts (neck, forelimbs, hindlimbs, chest, and back). Also, some of the meat’s physicochemical properties showed no difference. The meat ratios bone of groups fed PKC- and CSC-based diets were insignificant (p&gt;0.05) above the control. CSC significantly (p&lt;0.05) increased the moisture, while PKC significantly decrease the nitrogen and crude protein contents of the meat of experimental rabbits. This study suggests that rabbits could be raised on a diet formulated using CSC as a replacement for GNC, while a PKC-based diet tends to decrease the protein content of rabbit meat.

Dietary protein in early pregnancy and gestational diabetes mellitus: a prospective cohort study.

The relationship between dietary protein intake and the risk of gestational diabetes mellitus (GDM) remains inconsistent and unclear. Here, we examined the correlation between the various sources of protein intake among Chinese pregnant women and GDM. This prospective cohort study included 1060 pregnant women at 6-13+6 weeks of gestation from Guangdong Provincial Hospital for Women and Children, South China. The participants' intake of dietary protein was assessed using a validated quantitative food frequency questionnaire during the early trimester. GDM was diagnosed via an oral glucose tolerance test performed at 24-28 gestational weeks. Logistic regression analysis was used to evaluate the association between dietary protein intake during pregnancy and GDM. Furthermore, we applied restricted cubic splines to determine their linear relationship. About 26.3% (n = 279) of pregnant women were diagnosed with GDM. Animal protein intake was revealed to have a positive correlation with GDM risk (Q4 vs. Q1: OR, 2.78; 95% CI, 1.46-5.34; P = 0.015), whereas high intake levels of dietary plant protein were linked to reduced GDM risk (Q4 vs. Q1: OR, 0.43; 95% CI, 0.25-0.73). In stratified analysis, the relationship between protein and GDM was stronger during early pregnancy in women with obesity. However, total protein intake did not show a significant association with GDM. Our study findings suggest that a plant protein-based diet was associated with reduced GDM risk, whereas the dietary intake of animal protein was positively associated with GDM risk among Chinese women during early pregnancy.

The microbiota knows: handling-stress and diet transform the microbial landscape in the gut content of rainbow trout in RAS

BackgroundThe aim of the present study was to characterize the effects of handling stress on the microbiota in the intestinal gut contents of rainbow trout (Oncorhynchus mykiss) fed a plant-based diet from two different breeding lines (initial body weights: A: 124.69 g, B: 147.24 g). Diets were formulated in accordance with commercial trout diets differing in their respective protein sources: fishmeal (35% in fishmeal-based diet F, 7% in plant protein-based diet V) and plant-based proteins (47% in diet F, 73% in diet V). Experimental diets were provided for 59 days to all female trout in two separate recirculating aquaculture systems (RASs; mean temperature: A: 15.17 °C ± 0.44, B: 15.42 °C ± 0.38). Half of the fish in each RAS were chased with a fishing net twice per day to induce long-term stress (Group 1), while the other half were not exposed to stress (Group 0).ResultsNo differences in performance parameters were found between the treatment groups. By using 16S rRNA amplicon sequencing of the hypervariable region V3/V4, we examined the microbial community in the whole intestinal content of fish at the end of the trial. We discovered no significant differences in alpha diversity induced by diet or stress within either genetic trout line. However, the microbial composition was significantly driven by the interaction of stress and diet in trout line A. Otherwise, in trout line B, the main factor was stress. The communities of both breeding lines were predominantly colonized by bacteria from the phyla Fusobacteriota, Firmicutes, Proteobacteria, Actinobacteriota, and Bacteroidota. The most varying and abundant taxa were Firmicutes and Fusobacteriota, whereas at the genus level, Cetobacterium and Mycoplasma were key components in terms of adaptation. In trout line A, Cetobacterium abundance was affected by factor stress, and in trout line B, it was affected by the factor diet.ConclusionWe conclude that microbial gut composition, but neither microbial diversity nor fish performance, is highly influenced by stress handling, which also interacts with dietary protein sources. This influence varies between different genetic trout lines and depends on the fish’s life history.

Effects of supplementing a plant protein-rich diet with insect, crayfish or microalgae meals on gilthead sea bream (Sparus aurata) and European seabass (Dicentrarchus labrax) growth, physiological status and gut health

This study was aimed at evaluating growth response, gut health and physiological status of seabream (GSB) and European seabass (ES) juveniles fed diets totally deprived of fish meal and supplemented with alternative ingredients. Fish were fed four isoproteic (45%) and isolipidic (20%) diets in which meals from black soldier fly (Hermetia illucens, H) prepupae, whole red swamp crayfish (Procambarus clarkii, RC) or a microalgae blend (Tisochrysis lutea and Tetraselmis suecica, MA) were used as supplements to replace 10% protein of a fish meal-free, plant protein-based diet high in soybean meal (CV). Each diet was fed to triplicate fish groups kept in a RAS (Temperature 23.5 °C, Salinity 29 ppt) over 12 (GSB) and 18 (ES) weeks. In both fish species, MA diet resulted in the worst specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER) compared to CV. Diet H significantly improved the SGR only in GSB without affecting FCR. The dry matter apparent digestibility coefficient (ADC) was highest in the H diet (approximately 76%) and lowest in MA (around 73%), while an intermediate value was recorded for the RC diet, in both fish species. Slightly inflamed intestine and altered mucosa morphology were observed in both fish species fed on CV diet, highlighting a higher susceptibility of GSB to this diet. On the contrary, diets H, RC and MA led to a modulation of inflammatory gene expression in the distal intestine from the two fish species. However, while H and RC diets lead to a more evident intestine status improvement in GSB, in ES this result was evident even in response to MA diet administration. The MA diet induced a lowering of nutritional status compared to CV in both GSB and ES. Overall the results have shown that 10% protein from H and RC in a plant protein-based diet, tends to improve fish growth and gut health in both fish species. In ES also the diet including microalgae turned in a beneficial effect on fish gut health, compared to CV one, although it needs further refinement to reduce the adverse impact on growth and physiological status. Our findings suggest the potential use of insect and crayfish meals as functional ingredients in fish meal-free diets for GSB and ES, while further studies are needed to refine the use of microalgae as functional feed supplements in diets for sub-adult gilthead seabream and European seabass.

Squid industry by-product hydrolysate supplementation enhances growth performance of Penaeus monodon fed plant protein-based diets without fish meal

The poor growth of aquatic animals fed with diets containing high plant proteins has been attributed to low diet acceptability and feed value. Supplementation of protein hydrolysate, with high contents of free amino acids and soluble low molecular weight peptides, may increase the acceptability and feed value of a plant protein-based diet. In the present work, squid processing by-products were enzymatically hydrolyzed and used as a supplement in a plant protein-based diet, without fish meal, of Penaeus monodon to fully maximize the utilization of this marine resource. The hydrolysate was incorporated at 0, 0.5, and 1% levels in P. monodon diets containing 0 and 10% fish meal levels. Growth, digestive enzyme activities, muscle growth-, gut pro-inflammatory and immune-related gene expressions, and muscle morphometric measurements were evaluated as biological indices in an 8-week feeding trial. The squid by-product hydrolysate produced in the present study contains 90.25% protein, 5.84% lipid, and 3.91% ash, and has a molecular weight of 3.76 kDa. Supplementation at 1% hydrolysate in the experimental shrimp diet without fish meal resulted in the highest growth performance associated with increased feed intake, efficient feed and nutrient conversion and retention, enhanced digestive enzyme activities, upregulation of muscle growth- and immune-related genes, and suppression of the gut pro-inflammatory gene. The growth promotion is also linked with a significant increase in muscle mean fiber area, which suggests hypertrophic growth in shrimp. Generally, the supplementation of 1% squid by-product hydrolysate supported the growth of P. monodon fed on a plant protein-based diet without fish meal.

Efficacy of squid by-product hydrolysate supplementation on the growth performance, digestive enzyme activities and muscle growth-related genes expression of Penaeus monodon fed on plant protein-based diet

Efficacy of squid by-product hydrolysate supplementation on the growth performance, digestive enzyme activities and muscle growth-related genes expression of <i>Penaeus monodon</i> fed on plant protein-based diet

A plant-based diet supplemented with Hermetia illucens alone or in combination with poultry by-product meal: one step closer to sustainable aquafeeds for European seabass

BackgroundIncreasing demand for high-value fish species and pressure on forage fish is challenging aquaculture to ensure sustainable growth by replacing protein sources in aquafeeds with plant and terrestrial animal proteins, without compromising the economic value and quality of the final fish product. In the present study, the effects of a plant protein-based diet (CV), two plant-based diets in which graded amounts of plan protein mixtures were replaced with Hermetia illucens meal alone (VH10) or in combination with poultry by-product meal (PBM) (VH10P30), a fishmeal (FM) diet (CF) and an FM diet supplemented with H. illucens (FH10) on growth performance, gut health and homeostasis of farmed subadult European seabass were tested and compared.ResultsFish fed the VH10 and VH10P30 diets showed the highest specific growth rates and lowest feed conversion ratios among the tested groups. Expectedly, the best preservation of PI morphology was observed in fish fed the CF or FH10 diets, while fish fed the CV diet exhibited significant degenerative changes in the proximal and distal intestines. However, PBM supplementation mitigated these effects and significantly improved all gut morphometric parameters in the VH10P30 group. Partial substitution of the plant mixture with insect meal alone or PBM also induced most BBM genes and activated BBM enzymes, suggesting a beneficial effect on intestinal digestive/absorption functions. Regarding intestinal microbiota, fish fed diets containing H. illucens meal (FH10, VH10, VH10P30) had the highest richness of bacterial communities and abundance of beneficial genera such as Lactobacillus and Bacillus. On the other hand, fish fed CV had the highest microbial diversity but lost a significant component of fish intestinal microbiota, the phylum Bacteroidetes. Finally, skin pigmentation most similar to that of farmed or even wild seabass was also observed in the fish groups fed CF, FH10 or VH10P30.ConclusionPlant-based diets supplemented with PBM and H. illucens pupae meal have great potential as alternative diets for European seabass, without affecting growth performance, gut homeostasis, or overall fitness. This also highlights the importance of animal proteins in diets of European seabass, as the addition of a small amount of these alternative animal protein sources significantly improved all measured parameters.

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.

Nano-selenium supplementation in plant protein-based diets changed thyroid hormones status and hepatic enzymes activity in Acanthopagrus arabicus female broodfish and their offspring

A feeding trial was conducted to assess the effects of nano-selenium (n.Se) supplementation in a plant protein (PP)-based diet on female Acanthopagrus arabicus broodfish and their offspring. Two basal diets were prepared: a fish meal (FM)-based diet (FM-control) as a positive control and a PP-based diet. The PP-based diet was supplemented with n.Se at five levels including 0 (PP-control, as a negative control), 0.5, 1, 2, and 4 mg/ Kg. Brooders were fed for 90 days with one of the six experimental diets. Supplementing the PP-based diet with 2–4 mg n.Se/Kg markedly enhanced survival rate in 3-day post-hatch larvae (3DPH) larvae and total body length in newly born and 3DPH larvae. Serum triiodothyronine (T3) significantly decreased in females by supplementing PP-based diet with 1–4 mg n.Se/kg, meanwhile, serum thyroxine (T4) increased in females fed 1–4 mg n.Se/kg PP-based diets. The level of serum T3 in females fed FM-based diet was lower than those fed PP-based diet without n.Se supplementation (0.6 vs. 1.9 nmol/L−1). Meanwhile, the serum T4 was markedly higher in broodfish fed the FM-based diet than those fed the PP-based diet (21.9 vs. 14.3 nmol/L−1). The levels of T3 and T4 in 3DPH larvae originating from females fed the PP-based diet without n.Se supplementation were lower than in FM-based and n.Se supplemented PP-based groups (P < 0.05). Serum alkaline phosphatase (ALP) increased in females with increasing n.Se level in the PP-based diet. The highest and lowest ALP levels were in 3DPH larvae originating from females fed PP-based diet without n.Se supplementation and those fed with 1 mg n.Se/Kg PP-based diet, respectively (P < 0.05). The results of the present study suggest supplementing 2–4 mg n.Se in a PP-based diet can improve performance in A. arabicus brooders and larvae that are associated with modulation of thyroid hormones in this species.

Growth Enhancing Effects of Squid By-Product Hydrolysate in Plant Protein-Based Diet Fed to Black Tiger Shrimp, Penaeus monodon Fabricius, 1798

The present study evaluated the potential of squid by-product hydrolysate as fishmeal replacement in the plant-based diet of juvenile black tiger shrimp, Penaeus monodon Fabricius, 1798. Five experimental plant protein-based diets were formulated containing squid by-product hydrolysate to replace fishmeal at 0, 25, 50, 75 and 100 %. These experimental diets were fed to triplicate groups of P. monodon for 8 weeks. Results revealed that 25 % fishmeal replacement with squid by-product hydrolysate resulted in growth enhancement, attributable to increased feed intake and gut lactic acid bacteria proliferation. The shrimp fed with 100 % replacement level exhibited a similar growth response with the control group. Protein retention was not affected by the fishmeal replacement levels, but lipid retention was found higher in all treatments with squid by-product hydrolysate than the control. Digestive protease activity decreased with increasing levels of hydrolysate while α-amylase and lipase activities were not affected. Hepatopancreas histology showed thatB-cells dominated the control group while R-cells proliferated with increasing inclusion of dietary squid by-product hydrolysate. These results collectively indicate that fishmeal could be totally replaced with squid by-product hydrolysate and 25 % fishmeal replacement could promote the growth of juvenile P. monodon.

The optimal dietary taurine supplementation in zero fish meal diet of juvenile snakehead fish (Channa striata)

The most common alternative protein sources are plant-based proteins such as soybean meal but one of the limitations is taurine deficiency that can be especially detrimental for carnivorous fish. This study was to determine the important roles of dietary taurine on the growth performance, feed utilization and body composition of juvenile snakehead fish with an initial weight of 4.66–4.71 g/fish. Five test diets were investigated, using various taurine supplementation levels and both isonitrogenous and isoenergetic formulas: 1)control (fish meal inclusion); 2)zero fish meal diet (ZF) without taurine supplementation (T0); 3) ZF with taurine supplementation at 0.5% (T0.5); 4) ZF with taurine supplementation at 1.0% (T1.0); 5) ZF with taurine supplementation at 1.5% (T1.5). Fish were fed with five different dietary taurine levels for 60 days. Weight gain (WG), average daily gain (ADG) and specific growth rate (SGR) were higher in the control group of fish, followed by the T0.5 and T1.0 group but the lowest level was observed in fish fed the T0 and T1.5 (p < 0.05). The statistical results of Survival rate (SR), feed conversion ratio (FCR) and protein efficiency ratio (PER) were not significantly different (p > 0.05) among all experimental groups, whereas fish fed diet T0.5 and T1.0 had good trend in FCR and PER value similar to the control group. Dietary taurine might not affect on whole-body composition in juvenile snakehead fish (p > 0.0). Taurine accumulation in fish whole body and the liver both showed the increasing trends varying supplementation levels in each experimental diet. In the current study, taurine supplementation had no observable effects on the histological structures of liver and distal intestines of snakehead fish. This phenomenon indicated that the taurine supplementation at 0.5% in the plant protein-based diet (ZF) cloud be improved the growth performance and feed utilization of juvenile snakehead fish. Leading to, this is a positive sign of a possibility to reduce feed cost by completely taking fish meal out of a future commercial aquafeed for better aquaculture business sustainability.

Effects of nano‐Selenium supplementation in plant protein‐rich diet on reproductive performance and egg and larval quality of female Arabian yellowfin sea bream ( Acanthopagrus arabicus )

This study was conducted to examine effects of supplementing nano-selenium in a plant protein-based diet on reproductive performance of female Acanthopagrus arabicus. Two basal diets were formulated including a fishmeal (FM)-based diet and a plant protein (PP)-rich diet. FM-based diet served as a positive control (control) and the PP-rich diet was used as the basal diet for supplementing with 0, 0.5, 1, 2 and 4 mg N-Se Kg−1. Six groups of fish were fed one of the test diets over three months to spawning. Relative fecundity was higher in females fed 4 mg Kg−1 N-Se diet (p < .05). The greatest fertilization rate (FR) was found in broodfish fed 4 mg N-Se Kg−1 diet, but it was not significantly different from the FR in groups fed the control and 2 mg N-Se Kg−1 diets. Eggs from the females fed the control or 2 mg N-Se Kg−1 diets displayed higher hatchability (p < .05). The highest length and survival rate at 3-days post-hatch were observed in larvae of females fed 2 mg N-Se Kg−1 diet (p < .05). The results indicated that administration of 2–4 mg N-Se Kg−1 in PP-rich diets has beneficial effects on reproduction of female A. arabicus.

Citric acid minimizes oxidative stress in Amazonian fish (Colossoma macropomum) when fed plant protein-based diets

ABSTRACT This study aimed to evaluate the antioxidant potential of citric acid in plant protein based-diets offered to juvenile tambaqui, Colossoma macropomum. Four isonitrogenous and isoenergetic diets containing different levels of citric acid (0, 10, 20, and 30 g.kg−1) were formulated. Fish (n = 160; 27.56±1.03 g) were randomly distributed in 310-L water tanks (n = 16), with four replicates per treatment. After the experimental period (80 days), animals were anesthetized, and blood was collected for cell count. They were [...]

Liver Metabolome and Proteome Response of Turbot (Scophthalmus maximus) to Lysine and Leucine in Free and Dipeptide Forms

Omics approaches provide more metabolic information to explain the relationship between dietary nutrition and fish growth. This study aimed to explore the metabolome and proteome response of turbot (Scophthalmus maximus) fed diets containing lysine and leucine in free and dipeptide forms by the approaches of integrated liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics and isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics. Plant protein-based diets were formulated to contain the equivalent of lysine and leucine in free amino acid [crystalline amino acid (CAA)] and synthetic Lys-Leu (Lys-Leu) forms. The metabolome and proteome profiles of the liver were screened in fish fed either the CAA diet or the Lys-Leu diet after an 8-week feeding trial. Fish fed the Lys-Leu diet showed a significantly higher final body weight and a specific growth rate compared with fish fed the CAA diet. Protein- and amino acid-related metabolic processes in the liver were identified between the Lys-Leu and CAA groups based on differential metabolites and proteins. The proteolytic enzymes and amino acid transporters from differential proteins of the liver showed that the process of protein digestion and absorption may be affected by the different forms of lysine and leucine in the feed. A mechanistic target of rapamycin complex 1 and ubiquitin proteasome pathways were identified by differential proteins, which were involved in the processes of protein synthesis and degradation in the liver. Lysine degradation, tryptophan metabolism, alanine, aspartate, and glutamate metabolism, arginine biosynthesis, arginine and proline metabolism, and glycine, serine, and threonine metabolism were identified based on differential metabolites and proteins, which showed that the metabolism of various amino acids, including lysine, had been affected by both the CAA and Lys-Leu groups. In conclusion, the data of integrated metabonomics and proteomics suggested that different forms of lysine and leucine in the feed may affect liver metabolic processes including protein digestion and absorption, protein synthesis and degradation, and amino acid metabolism. In addition, a good correlation between differential metabolites and proteins was observed in amino acid metabolism by using the approaches of integrated LC-MS/MS-based metabolomics and iTRAQ-based proteomics.

Is it possible to cut down fishmeal and soybean meal use in aquafeed limiting the negative effects on rainbow trout (Oncorhynchus mykiss) fillet quality and consumer acceptance?

Poultry by-products (PBM) and Hermetia illucens prepupae meal (HM) are promising alternative protein sources for aquafeeds, being palatable, nutritious, and/or cost-effective, in addition to fostering circular economy. Their inclusion in rainbow trout (Oncorhynchus mykiss) feeds, although not detrimental for growth and wellbeing, leads to a decreased fatty acid (FA) quality, specifically, a decreased polyunsaturated FA content.The present study assessed the effect of five different diets on rainbow trout's biometric, marketable, and physical traits, oxidative status, fillet nutritional quality (of fresh and of 60-day stored fillets) and consumers' liking. The diets tested were: i) a positive-control diet, based on fishmeal (CF); ii) a plant protein-based diet (CV) resembling current commercial diets, used as additional control; 60% of the vegetable proteins were substituted with either iii) PBM (P60), iv) HM (H60) or v) both PBM and HM (H10P50).The principal component analysis considering all parameters showed two neat clusters, one grouping CF samples, the other grouping the rest of the samples. Specifically, hepatosomatic index and colour were significantly altered by the different administered diets. The most evident differences between dietary treatments were found in the FA profile, with CF fish showing a distinct FA profile in comparison to the other groups. Although the highest eicosapentaenoic and docosahexaenoic acid contents were found in CF group, the total polyunsaturated FA content was not significantly different between the dietary treatments, as linoleic and linolenic acids were the lowest in the CF fillets (p < 0.001). Storage seemed to exacerbate the differences found immediately after slaughter. As a consequence of the FA profile, conjugated dienes were significantly (p < 0.05) higher in the CF group compared to all the others. MDA-eq. content, although unaffected by diet at day 0, was higher (p < 0.01) after 60 days of storage in the CF group compared to H60, P60, and H10P50 fillets. Consumer likings were favourable and not statistically different between the dietary groups. Only 20% of the consumers criticised the gustative attributes of P60 and H10P50, while almost 25% of them criticised CF, CV, and H60.In summary, the P60, H60 and H10P50 diets were not less than the commercial-like CV diet. Combining PBM and HM showed positive results and needs further studies. Improving the n-3/n-6 ratio remains a priority to be addressed when formulating aquafeeds with innovative ingredients.

Muscle pigmentation in rainbow trout (Oncorhynchus mykiss) fed diets rich in natural carotenoids from microalgae and crustaceans

The amount of ingredients of marine origin used in salmonid feed industry is rapidly decreasing and fish meal and fish oil have been largely replaced by vegetable ingredients. New potential protein rich ingredients for aquafeed formulations should therefore be alternative to vegetable ones. The pattern of fillet pigmentation was thus assessed in rainbow trout (Oncorhynchus mykiss) fed for 15 weeks isoproteic (42%) and isolipidic (24%) diets deprived of fish meal where 10% of protein from a blend of vegetable ingredients was replaced by cyanobacteria and microalgae dried biomass (Arthrospira platensis, Tisochrysis lutea and Tetraselmis suecica) or Louisiana red swamp crayfish (Procambarus clarkii) meal. An automatic, repeatable, and objective image analysis tool for the integrated determination and direct visualization of fillet colour was applied to digital images. Colour of fillets was also measured with a chromameter, recording data as L*, a*, b* indexes and used to validate image analysis results. Fillet carotenoid and lipid contents were determined, and their pattern of variation was compared to that obtained by image analysis. Fillet colouring capacity of crayfish meal was also compared to that of commercial synthetic astaxanthin included in rainbow trout feed. To this last aim, test diets were administered for 12 additional weeks.The image analysis and colorimetric data consistently indicated that, even if characterized by a significantly higher carotenoid content respect to fish fed a vegetable diet, fillets of trout fed the cyanobacteria and microalgae including diets displayed an undesirable yellowish colour. P. clarkii meal instead resulted a promising functional ingredient to supplement plant protein-based diets for trout, in view of its lipid composition and astaxanthin content. In fact, despite a relatively low dietary carotenoid level due to low percentage of inclusion, a desirable pink pigmentation was clearly detectable in fillets of trout fed the crayfish meal-including diet, which resulted in colour differences which were less obvious relative to those of fish given the astaxanthin-supplemented feeds at the end of the additional 12 weeks.

183 Effects of Protein Supplementation on the Gut Bacterial Community Composition of Hybrid Striped Bass, Morone Chrysops X M. Saxatilis

Abstract Plant-based protein ingredients have become an attractive substitute for traditional animal sources in the aquaculture feed industry. However, inclusion in carnivorous fish diets is limited due to reduced digestibility, presence of anti-nutritional factors, and increased risk of digestive tract inflammation. To gain further insight on the adaptation of the fish digestive tract environment to plant-based protein sources, intestinal bacterial communities from Hybrid Striped Bass, Morone chrysops x M. saxatilis, fed diets supplemented with different protein sources were compared. Data were generated by Illumina MiSeq 2X300 sequencing of PCR generated amplicons targeting the V1–V3 regions of the 16S rRNA gene. A comparative analysis using the non-parametric Kruskal-Wallis test identified 17 highly represented species-level Operational Taxonomic Units (OTUs) that differed in abundance across dietary treatments (P &amp;lt; 0.05). Notably, OTU SD_McMs-0001 was at its highest abundance in samples from individuals fed poultry-fishmeal (PFM; 47.61% ± 0.92%) and plant protein-based (PP; 43.13% ± 1.76%) diets, while it was found in much lower abundance in the non-supplemented control diet samples (B; 4.29% ± 0.92%). It was predicted to be a novel species of the family Peptostreptococcaceae based on its limited 16S rRNA gene sequence identity to its closest valid relative (Peptostreptococcus russellii, 91%). In contrast, three Proteobacteria-affiliated OTUs (SD_McMs-0002, SD_McMs-0003, and SD_McMs-0004) were most highly represented in B diet samples, with averages of 30.28%, 27.22%, and 13.54%, respectively. They were in much lower abundance in the PFM and PP samples, with averages ranging between 0.18% and 4.82%, respectively. Based on 16S rRNA sequence comparisons, they were predicted to be strains of Plesiomonas shigelloides (99%), Ralstonia pickettii (99%) and Sphingomonas elodea (99%), respectively. These results indicate that protein supplementation affects gut bacterial community composition of Hybrid Striped Bass, but that the type of protein used has minimal or no detectable impact.