Plant Protein Diets Research Articles

Acacia seed proteins: Low or high quality? A comprehensive review.

The popularity of adding value to indigenous plant protein sources has increased due to the rise in the world population, high costs of animal protein as compared to plant proteins, and an increase in the consumer awareness of the nutritional and functional roles of dietary plant protein. Seeds of acacia plants (containing over 1,350 species) have considerable amount of protein (18.25% to 35.5%) and nutritionists have shown great interest in assessing the quality and functionality of proteins from these protein-rich plants. In this review, the overall nutritional and health-promoting properties of acacia seed (AS) species are introduced. Extraction, quality, and functional properties of proteins from different AS species are discussed. Furthermore, anti-nutritional components and protease inhibitors present in AS species and the effects of processing methods applied to lower the levels of anti-nutrients are also discussed. Previous applications of AS in food formulations are highlighted. This review aims to provide updated findings that have been reported on AS proteins and to highlight areas for further studies in order to increase the utilization potential of the seeds.

Protein-rich legume and pseudo-cereal crop suitability under present and future European climates

Abstract Replacing animal proteins with plant proteins in diets has been demonstrated to have both health and environmental advantages, driving a debate about the potential of protein-rich crops as dietary replacements for animal products. However, there is a lack of knowledge on how climate change could influence the potential for producing protein-rich crops. This study addresses this knowledge gap for the European Union. We analysed 13 protein-rich crops, using the crop suitability model EcoCrop and climate projections for the 2050s, based on 30 Global Circulation Models, under the Representative Concentration Pathway 4.5. The results suggest that current protein-rich crop distributions reflect climatic suitability. We demonstrate the heterogeneous impacts of climate change on crop suitability. In general, conditions in northern Europe were modelled to become more favourable for protein-rich crops, while in southern Europe modelled future climates limit the production of traditional protein-rich crops commonly grown there, including chickpea and lentil. Model results show an expanded area of high suitability for quinoa. Our results confirm the need for concerted breeding and research planning strategies to improve the tolerance of faba bean, lentil, and chickpea to the abiotic stresses that are predicted to become more common with climate change. At the same time, production in northern Europe can benefit from experimentation with protein-rich crops predicted to become more suitable there. Production planning and agricultural policy should consider these likely impacts, to encourage shifts that follow the emerging geographic patterns of crop suitability, and to support the resilience of protein-rich crop production in regions that may be negatively impacted by climate change.

The association of dietary macronutrients with anthropometric changes, using iso-energetic substitution models: Tehran lipid and glucose study

BackgroundThe consequences of optimal dietary macronutrient compositions especially quality of proteins on weight gain still remain controversial. The aim of the current study was to evaluate the iso-energetic substitution of dietary macronutrients in relation to anthropometric changes.MethodsThis prospective study was conducted on 2999 men and 4001 women aged 20–70 years who were followed for 3.6 years. A valid and reliable 168-item semi-quantitative food frequency questionnaire was used to assess usual dietary intakes. Weight (kg) and waist circumference (WC) (cm) changes were calculated by subtracting the weight and WC at baseline from their measurements at follow up. Participants were divided into two groups; those with no change or decrease in weight or WC and those with increase in weight or WC. Dietary macronutrients (percentage of energy) divided by 5 to calculate one unit.ResultsA one unit higher proportion of carbohydrates at the expense of all types of fatty acids was associated with weight loss in men (P < 0.05). A one unit higher proportion of plant proteins at the expense of animal protein (β = − 0.84), non-starch carbohydrates (β = − 0.86), saturated fat (β = − 0.76), mono-unsaturated fat (β = − 0.76) and poly-unsaturated fat (β = − 0.86) was associated with weight loss (P < 0.05). A one unit higher proportion of plant proteins at the expense of animal proteins (OR: 0.49), non-starch carbohydrates (OR: 0.49), saturated fat (OR: 0.49), mono-unsaturated fat (OR: 0.49), and poly-unsaturated fat (OR: 0.48) was associated with a lower risk of increase in WC (P < 0.05).ConclusionsA higher proportion of dietary plant protein in replacement of simple carbohydrates, fats and animal proteins was associated with a lower increase in weight or WC.

Effect of the total replacement of fishmeal with plant proteins and supplemental essential amino acids in the extruded diet on antioxidants genes, enzyme activities, and immune response in juvenile blunt snout bream

Four diets were formulated with or without fishmeal (FM) and essential amino acid (EAA) supplementation fed to the blunt snout bream throughout 8 weeks. The results showed that total cholesterol level (TC) was decreased significantly against FM reduction (P 0.05). Catalase (CAT) activity and glutathione (GSH) content were significantly augmented and diminished in the group fed diet 3 respectively (P 0.05). Glutathione peroxidase (GPx) activity was elevated significantly either by reducing FM or supplementing EAA (P 0.05), whereas the relative expression of copper-zinc superoxide dismutase (Cu/Zn-SOD) decreased against FM reduction (P < 0.05). The relative expressions of Interleukin 8 (IL-8), tumour necrosis factor-α (TNF-α), interleukin 10 (IL10), and nuclear factor-kappa B (NF-κB) were diminished significantly in FM-reduced groups (P < 0.05). The supplementation of EAA significantly increased the relative expression of signal transducer and activator of transcription 4 (STAT4) (P < 0.05). In conclusion, the results revealed that dietary plant proteins with EAA supplementation significantly affected the physiological status and immune responses in blunt snout bream.

Plant protein diet suppressed immune function by inhibiting spiral valve intestinal mucosal barrier integrity, anti-oxidation, apoptosis, autophagy and proliferation responses in amur sturgeon (Acipenser schrenckii)

An 8-week growth trial was conducted to investigate the effects of replacing dietary fishmeal with a plant protein blend on the growth performance, mucosal barrier integrity and the related regulation mechanism in Amur Sturgeon (Acipenser schrenckii) with initial weight of 87.48 g. Three isonitrogenous and isoenergetic diets were prepared. A basal diet containing 540 g/kg fishmeal (P0), whereas the other two diets were formulated by replacing 50% and 100% of FM with plant protein blend (soybean protein concentrate and cottonseed protein concentrate), and named as P50 and P100, respectively. Although essential amino acids, fatty acids, and available phosphorus had been balanced according to the nutrient requirement of sturgeon, compared with the fish of P0 and P50, the full plant protein diet (P100) significantly reduced growth performance and survival, and accompanied with serious spiral valve intestinal (SVI) damage. The increased tissue necrosis and failed responses in anti-oxidation, programming apoptosis, autophagy and cell proliferation system were regulated by inhibiting ERK1 phosphorylation, which indicated that SVI hypoimmunity and functional degradation were the main reasons for the high mortality and low utilization ability of plant protein in Amur sturgeon.

Plant- and animal-protein diets in relation to sociodemographic drivers, quality, and cost: findings from the Seattle Obesity Study

Promoting plant-based proteins is at the forefront of many initiatives in public health nutrition. The aim of this study was to characterize the sociodemographic drivers of plant-based protein diet consumption, and to study these in relation to diet quality and cost. The Seattle Obesity Study series (SOS I and II) yielded the study sample (n=1636). Sociodemographic data were obtained by survey self-report. Diet quality and cost came from the Fred Hutchinson Cancer Research Center Food-Frequency Questionnaire linked to retail food prices. The Healthy Eating Index 2010 (HEI-2010) and mean adequacy ratio (MAR) served as measures of diet quality. Linear regressions with robust standard errors examined associations. Total proteins contributed 16.8% of daily dietary energy. The breakdown by animal and plant proteins was 10.9% and 5.9%, respectively. The sociodemographic factors associated with plant-protein consumption were a positive attitude towards healthy eating and higher education but not income. Plant-protein diets were characterized by severalfold increases in nuts and seeds, soy and legumes, but much less meat, poultry, dairy, solid fats, and added sugars. Higher quartiles of plant-based diets were associated with significantly higher HEI-2010 (β: 13.0 from quartile 1 to quartile 4; 95% CI: 11.8, 14.3) and higher MAR (β: 6.0; 95% CI: 3.5, 8.5) with minimal impact on diet costs (β: 0.35; 95% CI: 0.04, 0.67). In contrast, higher quartiles of animal-protein diets were associated with higher diet costs (β: 1.07; 95% CI: 0.77, 1.36) but lower HEI-2010 (β: -3.2; 95% CI: -4.5, -1.9). Each additional 3% of energy from plant proteins was associated with an 8.4-unit increase in HEI-2010 (95% CI: 7.6, 9.1) and with a 4.1-unit increase in MAR (95% CI: 2.7, 5.5) with a minimal increase in diet cost (β: 0.28; 95% CI: 0.06, 0.50). Plant-based protein diets may be a cost-effective way to improve diet quality at all levels of income. Future research needs to evaluate the quality of plant-based protein in relation to amino acids and health.

Nutrient digestibility, digestive enzymes activity, bile drainage alterations and plasma metabolites of meagre (Argyrosomus regius) feed high plant protein diets supplemented with taurine and methionine

The supplementation effect of a high plant protein diet with methionine and taurine on nutrient digestibility, digestive enzymes activity, plasma and intestine bile acid content, and plasma metabolites was assessed in meagre juveniles. A control (CT) diet was formulated with 42% crude protein and 18% lipids, and including only 10% fishmeal, corresponding to 18% of the dietary protein level. Three other diets were formulated similar to the control but supplemented with 0.26% methionine (MET), 1.0% taurine (TAU), or 0.26% Met plus 1.0% Tau (MET+TAU), in a 2 × 2 factorial design. Final dietary Met levels were 0.75 and 1.0%, and Tau levels were 0.10 and 1.20%. Diets were fed to triplicate groups of 103 ± 21.2 g fish, twice a day, to apparent satiation. Fish were assembled in fiberglass tanks (60 L of water capacity), each one with feces settling column. Dietary Met supplementation increased apparent digestibility of dry matter, protein, lipids, and energy while dietary Tau supplementation increased lipids digestibility. Lipase activity was not affected by dietary methionine level, but it was higher in fish fed the taurine supplemented diet at the higher methionine level. Proteases and amylases activities were not affected by diet composition. Total bile acid in plasma and anterior intestine increased with dietary Tau supplementation. Dietary Tau supplementation also increased plasmatic levels of cholesterol, total proteins, and triglycerides. Overall, results of this study indicate that dietary methionine supplementation improved diet digestibility and that dietary taurine supplementation improved lipid digestibility and positively affected lipid metabolism in meagre.

Dietary Plant Protein and the Progression of Metabolic Syndrome over 9 Years (OR27-08-19)

ObjectivesMetabolic syndrome is a precursor to many leading causes of death in the United States including cardiovascular disease, stroke, and diabetes. Diet plays a major role in preventing or exacerbating the development of metabolic syndrome. Increasing plant protein intake may help to reduce risk of developing metabolic syndrome. The purpose of this study was to examine the possible relationship between metabolic syndrome progression and % of protein from plant sources in the diet. MethodsThe ARIC dataset was used to compare changes in the number of metabolic syndrome criteria (0-5) over a 9-year period to average % of protein from plant sources for 10,038 Americans age 45–64. Quartiles of plant protein intake were controlled for important covariates in linear regression. ResultsAs hypothesized, quartiles with higher percentages of protein intake from plant sources showed a decrease in metabolic syndrome score [B (change in metabolic syndrome score over 9 years per plant protein quartile) = -0.039; 95% confidence interval (CI): -0.063, -0.016] over 9 years of follow up. Waist circumference was the most significantly associated metabolic syndrome factor (B = -0.053; 95% CI -0.030, -0.011). A decrease in BMI was similarly correlated with higher intakes of plant proteins (B = -0.077; 95% CI -0.214, -0.0112). ConclusionsThese results suggest that a higher intake of plant proteins could be protective against increased BMI, waist circumference, and worsening metabolic syndrome and therefore may reduce risk of cardiovascular disease, diabetes, and stroke. Funding SourcesUniversity Funding.

The association of dietary animal and plant protein with putative risk markers of colorectal cancer in overweight pre-diabetic individuals during a weight-reducing programme: a PREVIEW sub-study.

Diets with increased protein content are popular strategies for body weight regulation, but the effect of such diets for the colonic luminal environment is unclear. We aimed to investigate the associations between putative colorectal cancer-related markers and total protein intake, plant and animal proteins, and protein from red and processed meat in pre-diabetic adults (> 25years). Analyses were based on clinical and dietary assessments at baseline and after 1year of intervention. Protein intake was assessed from 4-day dietary records. Putative colorectal cancer-related markers identified from 24-h faecal samples collected over three consecutive days were: concentration of short-chain fatty acids, phenols, ammonia, and pH. In total, 79 participants were included in the analyses. We found a positive association between change in total protein intake (slope: 74.72 ± 28.84µmol per g faeces/E%, p = 0.01), including animal protein intake (slope: 87.63 ± 32.04µmol per g faeces/E%, p = 0.009), and change in faecal ammonia concentration. For change in ammonia, there was a dose-response trend from the most negative (lowest tertile) to the most positive (highest tertile) association (p = 0.01): in the high tertile, a change in intake of red meat was positively associated with an increase in ammonia excretion (slope: 2.0 ± 0.5µmol per g faeces/g/day, p < 0.001), whereas no such association was found in the low and medium tertile groups. Increases in total and animal protein intakes were associated with higher excretion of ammonia in faeces after 1year in overweight pre-diabetic adults undertaking a weight-loss intervention. An increase in total or relative protein intake, or in the ratio of animal to plant protein, was not associated with an increase in faeces of any of the other putative colorectal cancer risk markers. ClinicalTrials.gov Identifier: NCT01777893.

Dietary proteins and protein sources and risk of death: the Kuopio Ischaemic Heart Disease Risk Factor Study

Previous studies investigating protein intake in relation to mortality have provided conflicting results. We investigated the associations of dietary protein and protein sources with risk of disease death in the prospective, population-based Kuopio Ischaemic Heart Disease Risk Factor Study. The study population consisted of 2641 Finnish men, aged 42-60 y at baseline in 1984-1989. We estimated protein intakes with 4-d dietary records at baseline and collected data on disease deaths from the national Causes of Death Register. Cox proportional hazards regression models were used to estimate HRs and 95% CIs. During the average follow-up of 22.3 y, we observed 1225 deaths due to disease. Higher intakes of total protein and animal protein had borderline statistically significant associations with increased mortality risk: multivariable-adjusted HR (95% CI) in the highest compared with the lowest quartile for total protein intake=1.17 (0.99, 1.39; P-trend across quartiles=0.07) and for animal protein intake=1.13 (0.95, 1.35; P-trend=0.04). Higher animal-to-plant protein ratio (extreme-quartile HR=1.23; 95% CI: 1.02, 1.49; P-trend=0.01) and higher meat intake (extreme-quartile HR=1.23; 95% CI: 1.04, 1.47; P-trend=0.01) were associated with increased mortality. When evaluated based on disease history at baseline, the association of total protein with mortality appeared more evident among those with a history of type 2 diabetes, cardiovascular disease, or cancer (n=1094) compared with those without disease history (n=1547) (P-interaction=0.05 or 0.07, depending on the model). Intakes of fish, eggs, dairy, or plant protein sources were not associated with mortality. Higher ratio of animal to plant protein in diet and higher meat intake were associated with increased mortality risk. Higher total protein intake appeared to be associated with mortality mainly among those with a predisposing disease. This trial was registered at clinicaltrials.gov as NCT03221127.

Metabolic disorder induces fatty liver in Japanese seabass, Lateolabrax japonicas fed a full plant protein diet and regulated by cAMP-JNK/NF-kB-caspase signal pathway

A 10-week growth trial was conducted to investigate the effects of replacing dietary fishmeal with plant proteins on nutrition metabolism, immunity, inflammation and apoptosis responses in liver tissues of Japanese seabass, Lateolabrax japonicas (initial body weight = 10.42 ± 0.01 g). Two isonitrogenous and isoenergetic diets were formulated. A basal diet containing 54% fishmeal (FM), whereas another diet was prepared by totally replacing FM with a plant protein blend (PP) composed with soybean protein concentrate and cottonseed protein concentrate. Although essential amino acids, fatty acids, and available phosphorus had been balanced according to the FM diet profile, the significantly lower growth performance, metabolic disorder, and fatty liver symptom were observed in the PP group. Compared with the FM group, fish in the PP group showed significantly lower plasma free EAA level and PPV. Glucose metabolism disorder was expressed as the uncontrollable fasting glycolysis and pyruvate aerobic oxidation at postprandial 24 h with significantly up-regulated GK, PK and PDH genes expression, which potentially over-produced acetyl-CoA as the substrate for protein and lipid synthesis. Significantly reduced plasma GLU, but increased GC level, along with very significantly reduced liver GLY storage could be observed in the PP group. Plasma TG and hepatic NEFA contents were significantly decreased, but the hepatic TC content was very significantly increased in the PP group, in addition, hepatocyte vacuolation appeared. The significantly up-regulated cholesterol synthesis gene (HMGCR) expression but down-regulated bile acid synthesis gene (CYP7A1) expression could be the main reason for the fatty liver induced by cholesterol accumulation. The reduced plasma IgM content accompanied by the up-regulated mRNA levels of pro-inflammatory cytokines (TNFα and IL1β) and activated apoptosis signals of liver tissues were found in the PP group. The hyperthyroidism (higher plasma T3 and T4) and the accelerated energy metabolism rate decreased the growth performance in the PP group. The activated p65NF-kB may promote the hepatocytes apoptosis via the extrinsic pathway (caspase8/caspase3). Simultaneously, a “self-saving" response could be observed that activated cAMP promoted the lipolysis/β-oxidation process and up-regulated gene expression of anti-inflammatory cytokine IL10 via promoting CREB expression, further inhibited the over-phosphorylation of JNK protein, which might impede the intrinsic apoptosis pathway (caspase9/caspase3). In conclusion, the nutrient and energy metabolic disorder induced fatty liver related to the cholesterol accumulation in Japanese seabass fed full PP diet, which was under the regulation by cAMP-JNK/NF-kB-caspase signaling pathway. The hemostasis phosphorylation of JNK protein protected the liver tissues from more serious damage.

Effects of silymarin on growth performance, antioxidant capacity and immune response in turbot (Scophthalmus maximus L.)

AbstractA 9‐week feeding trial was conducted using triplicate groups of turbot (6.50 ± 0.01 g) to explore the potential effects of silymarin. Three concentrations of silymarin (100, 200, and 400 mg/kg) were added to the plant protein‐based diet. Fish were randomly distributed into fiberglass tanks (30 fish per tank). The results showed that adding 100 mg/kg silymarin significantly improved the growth performance, with no effects on feed utilization. The antioxidant capacity in the liver was significantly improved in the 100 mg/kg and 200 mg/kg silymarin groups by not only inducing the activities of superoxide dismutase (SOD) and catalase but also increasing the messager RNA (mRNA) expression levels of SOD, glutathione peroxidase, and peroxiredoxin 6. Meanwhile, supplying 100 and 200 mg/kg of silymarin enhanced the heights of villi and enterocytes. Silymarin supplementation reduced the mRNA expression of interleukin‐8 and tumor necrosis factor‐α but induced the expression of transforming growth factor‐β (TGF‐β) in the intestine. These results indicated that silymarin was a potential nutraceutical that could enhance the growth performance and health status of turbot fed in a high plant protein diet. Adding 100 mg/kg silymarin to the plant protein diet achieved optimal performance in turbot.

An evaluation of mixed plant protein in the diet of Yellow River carp (Cyprinus carpio): growth, body composition, biochemical parameters, and growth hormone/insulin-like growth factor 1.

The aim of this work is to evaluate the effects of dietary inclusion of mixed plant protein (MP) (rapeseed meal:cottonseed meal:peanut meal = 1:1:1) on growth, body composition, blood biochemical parameters, growth hormone/insulin-like growth factor 1, and relative non-specific immune response in Yellow River carp Cyprinus carpio. Five isonitrogenous and isoenergetic trial diets were formulated to replace fish meal at 0 (MP0, control), 25% (MP25), 50% (MP50), 75% (MP75), and 100% (MP100) mixed plant protein, respectively. The 25% mixed plant protein did not affect the weight gain, specific growth rate, and protein efficiency ratio, whereas these parameters were depressed by 50% and above mixed plant protein. The whole body protein content gradually decreased with increasing dietary MP; meanwhile, the whole body lipid content is the opposite. The MP75 and MP100 diets adversely affected the glucose level, total cholesterol value, alanine transaminase, and aspartate transaminase activity of serum. Fish fed MP75 and MP100 diets showed higher growth hormone level than that of MP0 diet; however, the insulin-like growth factor 1 level got the opposite result. The 50% and above inclusion of MP decreased lysozyme activity and increased malondialdehyde content. In conclusion, no more than 50% of fish meal could be replaced by mixed plant protein in diet. However, 50% and above inclusion of mixed plant protein in diet could depress the growth, insulin-like growth factor 1 level, and non-specific immune response, and significantly affect the whole body composition and serum biochemical parameters in Yellow River carp.

Effects of dietary plant protein sources influencing hepatic lipid metabolism and hepatocyte apoptosis in hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀)

A 56-day feeding trial was conducted to evaluate the effects of replacing dietary fish meal (FM) with a complementary mixture of plant protein (PP) consisting of soybean meal (SBM), corn gluten meal (CGM) and cottonseed meal (CSM) on hepatic lipid metabolism and hepatocyte apoptosis in juvenile hybrid grouper, Epinephelus lanceolatus♂ × E. fuscoguttatus♀ (31.64 ± 0.82 g). A basal diet (FM60) with FM as the sole protein source was compared to diets progressively replacing 25% (FM45), 50% (FM30) and 75% (FM15) of FM protein. No significant differences were observed in growth performance and feed utilization when up to 75% of FM protein was replaced by PP sources. The hepatosomatic index (HSI) was markedly increased as dietary PP inclusion increased, but crude lipid content in the liver showed the opposite trend. Plasma cholesterol (CHO), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) of fish fed the PP containing diets were all significantly lower than the control. Liver histological analysis showed a higher levels of hepatocyte vacuolization and nuclear pycnosis occurred as dietary PP inclusion increased, but the amounts of hepatic lipid droplets showed a decreasing trend with increasing PP inclusion levels. Moreover, dietary PP inclusion down-regulated the mRNA levels of lipid metabolism-related genes including peroxisome proliferator-activated receptor alpha (PPARα), carnitine palmitoyltransferase 1 (CPT1), apolipoprotein AI (Apo-AI) and lipoprotein lipase (LPL). On the other hand, dietary PP sources also down-regulated the apoptosis-related genes including caspase-3, caspase-7, caspase-8 and p53. The present study provided new evidence for the PP sources-induced lipid metabolism in carnivorous fish, and provided new insight into the relationship between dietary PP sources and cell apoptosis.

Effects of plant and animal high protein diets on immune-inflammatory biomarkers: A 6-week intervention trial

Pro-inflammatory biomarkers are well-established contributors to insulin resistance and represent valid targets for diabetes management and prevention. Yet, little is known whether nutrition could play a role in modulating various aspects of immune-inflammatory responses. Our aim is to assess the effect of isocaloric animal and plant protein dietary interventions on selected biomarkers representing various immune-inflammatory pathways. We enrolled 37 participants with type 2 diabetes (age 64±6 years, body mass index 30.2±3.6kg/m2, glycated hemoglobin 7.0±0.6%) who underwent an either high-animal protein (AP) or high-plant protein (PP) diet (30E% protein, 40E% carbohydrates, 30E% fat) for 6-weeks. Clinical examinations were performed at beginning and end of the study. Levels of pro-inflammatory adipokines [chemerin, progranulin], cytokines [tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), soluble urokinase-type plasminogen activator receptor (suPAR), transforming growth factor beta 1 (TGF-β1)], and proteins [calprotectin, lactoferrin and growth differentiation factor 15 (GDF-15)] were determined in blood serum using enzyme-linked immunosorbent assay. Chemerin and progranulin concentrations decreased following AP and PP diets. TGF-β1 increased in AP and decreased in PP, whereas calprotectin increased in PP and decreased in AP. No statistically significant differences in the concentrations of IL-6, TNF-α, suPAR, lactoferrin and GDF-15 could be seen in either of the protein diet arms. These results suggest that both AP and PP diets may effectively reduce the levels of the pro-inflammatory adipokines chemerin and progranulin. The effects on the additional immune-inflammatory biomarkers seem to be more complex. NCT02402985 (ww.clinicaltrials.gov).

A diet-change modulates the previously established bacterial gut community in juvenile brown trout (Salmo trutta)

The aim of the present study was to investigate the impact of dietary plant proteins on the gut microbiome of first feeding brown trout (Salmo trutta) reproduced from wild stocks and to evaluate whether the initial microbiome of brown trout fry can be permanently manipulated by the first feeding diet. Therefore, brown trout fry was fed diets based on either 0%, 50% or 90% plant-derived proteins from first feeding onwards and via 16S rRNA gene sequencing a strong dietary influence on the bacterial gut community on phylum and order level was detected. Proteobacteria and Fusobacteria were significantly enhanced when fishmeal was integrated into the experimental diet, whereas plant-derived proteins significantly promoted Firmicutes and Bacteroidetes. In order to evaluate whether the first feeding diet had a permanent effect on the initially established microbial gut community of juvenile brown trout, a cross-over diet-change was applied 61 days post first feeding. 48 days after the diet-change, the gut microbiome of all dietary groups was significantly different from the one initially established after first feeding. Moreover, the first feeding diet had no statistically significant influence on the gut microbiome after the diet-change, demonstrating no permanent effect on the gut microbiome formation.

High-throughput sequencing of gut microbiota in rainbow trout (Oncorhynchus mykiss) fed larval and pre-pupae stages of black soldier fly (Hermetia illucens)

Black soldier fly (Hermetia illucens) meal is a potential alternative to fishmeal and plant proteins in diets for farmed fish since it can be produced on organic waste substrates, requires little energy and water inputs and contains high levels of essential amino acids. Recent studies have partially replaced fishmeal with black soldier fly meal, however, research on their impact on gut microbiota of fish is limited. In a five week experiment, juvenile rainbow trout (Oncorhynchus mykiss) were fed either a reference diet based on fishmeal or three diets with 30% inclusion of black soldier fly meals in the form of pre-pupae, larvae or defatted-larvae. The combined luminal content and mucosa were collected from the distal intestine of three fish per tank with four tanks per diet (n = 12) and 16S rRNA gene amplicons were sequenced using the Illumina MiSeq platform. Feeding the insect-based diets increased the alpha-diversity of bacteria and abundance of lactic acid bacteria, which may be due to the addition of dietary chitin. Compared with fishmeal, feeding insects resulted in higher abundance of phyla Firmicutes and Actinobacteria with lower abundance of Proteobacteria. Fish fed the full-fat meals had higher abundance of Corynebacterium that was attributed to its ability to produce lipase and the high content of dietary lipids as a substrate. Bacillaceae was increased in fish fed both larvae diets and unchanged in the pre-pupae diet, which indicated that life-cycle stage of the insect influenced the gut microbiota. Based on these results, we found that feeding black soldier flies increased diversity and altered the composition of gut bacteria of rainbow trout, which were further influenced by life-cycle stage and lipid content of the insect meal.

Soybean meal replacement by corn distillers dried grains with solubles (DDGS) and exogenous non-starch polysaccharidases supplementation in diets for gilthead seabream (Sparus aurata) juveniles

A growth trial was conducted to evaluate the effect of dietary plant-protein replacement by corn distillers dried grains with solubles (DDGS), and of exogenous carbohydrases supplement (Natugrain®TS, BASF) in gilthead seabream (Sparus aurata) juveniles. For that purpose, a basal diet was formulated with 35% of fish meal and 20% soybean meal (SBM) as main protein sources. Two other diets were formulated incorporating 15 or 35% of DDGS, replacing 37.5% or 100% of SBM (diets DDGS15 and DDGS35, respectively). Another diet was formulated similar to diet DDGS35 and supplemented with 0.1% of a commercial non-starch polysaccharidases complex, Natugrain®TS, BASF (CHOase; diet DDGS35ENZ). Triplicate groups of fish (IBW = 15 ± 1 g) were fed the experimental diets for 67 days at 22 °C. At the end of the trial, growth performance, voluntary feed intake, feed efficiency, protein and energy retention were not affected by dietary DDGS incorporation. Dietary CHOase supplementation also did not affect growth performance, but increased feed efficiency, nitrogen and energy retention. Dietary inclusion of DDGS tended to decrease production cost (€ per kg of fish), and dietary CHOase supplementation further reduced production cost, which was significantly lower with diet DDGS35ENZ than with the basal diet. Whole-body composition, hepatosomatic and visceral indexes were not affected by the dietary inclusion of DDGS, though a trend was noticed for a decrease of whole-body lipid, energy, and visceral index with the increase dietary DDGS. Plasma glucose, protein, albumin, and globulins levels were similar among diets, whereas plasma triglycerides increased, and cholesterol decreased with the increase of dietary DDGS. Hepatic glycolytic enzymes activities (hexokinase and glucokinase) were similar among groups, while gluconeogenic (fructose biphosphatase) activity, GDH and ASAT activities decreased with the increase of dietary DDGS. The hepatic activity of oxidative stress-related enzymes catalase and superoxide dismutase were not affected by dietary treatments, but G6PDH and GR activities decreased, and liver lipid peroxidation increased with dietary DDGS level. Dietary CHOase supplementation decreased overall lipid peroxidation.Overall, results of this study indicate that total replacement of SBM by DDGS in diets for gilthead seabream did not compromise growth performance or feed utilization efficiency, while supplementation of DDGS-based diet with exogenous carbohydrases improved feed utilization efficiency and economic efficiency ratio.

Dietary fructooligosaccharide can mitigate the negative effects of immunity on Chinese mitten crab fed a high level of plant protein diet

An 8-week feeding trial was carried out under controlled condition to evaluate the effect of dietary fructooligosaccharide (FOS) on growth performance, whole body composition, antioxidant status and immunity of crabs fed high levels of plant protein diets. Thus, six experimental diets were formulated (designated as F0P50, F0P60, F0P70, F0.2P50, F0.2P60 and F0.2P70), which contain two FOS levels (0 or 0.2%) and three plant protein levels (50, 60, or 70%) according to a 2 × 3 factorial design. The results showed that weight gain increased significantly as dietary plant protein level decreased from 70% to 50%. At 50% plant protein level, the addition of 0.2% FOS can significantly elevate weight gain (WG) (P < 0.05). The highest value in survival rate was observed in crabs fed F0.2P50 and F0.2P60 diet. Crabs fed F0.2P50 diet showed significantly higher crude protein content (P < 0.05) compared with those in other groups, but there were no significant differences in the contents of moisture, crude lipid and ash among all groups (P > 0.05). Catalase (CAT) activity in crabs fed F0.2P50 increased significantly (P < 0.05) compared with crabs fed F0P60, F0P70, F0.2P60 and F0.2P70, but malondialdehyde (MDA) concentrations decreased significantly (P < 0.05). Meanwhile, nitric oxide (NO) concentration, acid phosphatase (ACP) and alkaline phosphatase (AKP) activities of crabs fed 0.2% FOS diets increased significantly (P < 0.05) compared with crabs fed 0% FOS diets. The expressions of prophenoloxidase (propo) was significantly (P < 0.05) affected only by dietary plant protein levels with the highest values observed in 50% plant protein diet, whereas the opposite was true for Myeloid differentiation factor 88 (myd88). The mRNA expressions of mitochondrial manganese superoxide dismutase (mtmnsod), lipopolysaccharide-induced TNF-α factor (litaf) and toll like receptors (tlrs) were significantly affected (P < 0.05) by both FOS and plant protein levels. The cytosolic manganese superoxide dismutase (cytmnsod) mRNA expressions in F0.2P50 and F0.2P60 groups were significantly higher than those in F0P70 and F0.2P70 groups. The results in this study indicated that supplementation with 0.2% FOS can enhance growth performance in crabs fed lower plant protein diets and as well improve immunity in those fed with higher plant protein diets.

Growth and feed intake regulation responses to anorexia, adaptation and fasting in Japanese seabss, Lateolabrax japonicas when fishmeal is totally replaced by plant protein

In captivity, Lateolabrax japonicas, a carnivorous fish, is given fishmeal-based diets and does not thrive when fed plant proteins. In the present study, when dietary fishmeal was totally replaced with plant protein, the fish showed anorexia in the first 2 weeks followed by the phenotypes of feeding adaptation and compensation after 4 weeks. The negative energy balance resulting from anorexia in fish given the plant-based diet induced up-regulation of ghrelin and down-regulation of leptin transcription in the stomach, along with high plasma ghrelin concentration, which indicated that the peripheral organs were effective at sensing the nutrients intake deficiency. However, activation of mTOR in the hypothalamus decreased the phosphorylation of downstream S6K1, accompanied by further up-regulation of anorectic gene POMC and down-regulation of orexigenic gene AgRP expression in anorectic stage, indicating that the central nervous system (CNS) failed to respond to peripheral hungry. As soon as the fish adapted to the plant protein diet, no matter pre-prandial or fasting for 3 weeks, the regulating responses in CNS were consistent with the peripheral energy state. Therefore, the voluntary anorexia induced by plant protein was under different regulation mechanism from feeding adaption and the passive feeding inhibition caused by fasting.