Enterocyte Height Research Articles

The Indigenous Probiotic Lactococcus lactis PH3-05 Enhances the Growth, Digestive Physiology, and Gut Microbiota of the Tropical Gar (Atractosteus tropicus) Larvae.

Probiotics in aquaculture hold promise for enhancing fish health and growth. Due to their increased specificity and affinity for their host, indigenous probiotics may offer isolated and potentially amplified benefits. This study investigated the effects of Lactococcus lactis PH3-05, previously isolated from adults of tropical gar (Atractosteus tropicus), on the growth, survival, digestive enzyme activity, intestinal morphology, expression of barrier and immune genes, and intestinal microbiota composition in the larvae of tropical gar. Larvae were fed with live L. lactis PH3-05 concentrations of 104, 106, and 108 CFU/g for 15 days alongside a control diet without probiotics. Higher concentrations of L. lactis PH3-05 (106 and 108 CFU/g) positively influenced larval growth, increasing hepatocyte area and enterocyte height. The 106 CFU/g dose significantly enhanced survival (46%) and digestive enzyme activity. Notably, the 108 CFU/g dose stimulated increased expression of muc-2 and il-10 genes, suggesting enhanced mucosal barrier function and anti-inflammatory response. Although L. lactis PH3-05 did not significantly change the diversity, structure, or Phylum level composition of intestinal microbiota, which was constituted by Proteobacteria, Bacteroidota, Chloroflexi, and Firmicutes, an increase in Lactobacillus abundance was observed in fish fed with 106 CFU/g, suggesting enhanced probiotic colonization. These results demonstrate that administering L. lactis PH3-05 at 106 CFU/g promotes growth, survival, and digestive health in A. tropicus larvae, establishing it as a promising indigenous probiotic candidate for aquaculture applications.

Intestinal histomorphology of silver catfish fed diets supplemented with Citrus x Aurantium essential oil

The aim of this study was to investigate the effects of dietary Citrus x aurantium essential oil (EOCA) on the growth and intestinal histomorphology of silver catfish (Rhamdia quelen) fingerlings. Five diets with different doses of EOCA (0.0, 0.25, 0.5, 1.0, and 2.0 mL/kg diet) were evaluated. At the end of 60 days, the growth performance was positively correlated with dietary EOCA supplementation. The results showed an increase in fold height in the middle intestine (MI) of fish fed the EOCA diet compared to the control group. In the anterior intestine (AI), the enterocyte height increased, while the goblet cell number decreased in all EOCA-supplemented diets. The goblet cell number in the MI and posterior intestine (PI) was higher with EOCA and lowest in the control group. Diets with EOCA did not affect the fold height in the PI. Similarly, to the AI, the fold width in PI increased in the 0.5 mL/kg treatment compared to the control group. These results revealed that dietary supplementation with EOCA, primarily at a dose of 0.5 mL EOCA/kg diet, promoted positive effects on the intestinal morphology of R. quelen, indicating that the use of EOCA extracted from sweet orange peel, a fruit residue, could be considered in fish diets.

Nucleotídeos purificados em rações para reprodutores e proles regulam a atividade de enzimas digestivas e a morfologia intestinal em tilápia-do-Nilo

In this study, the effects of adding nucleotides to diets for broodstock and offspring of Nile tilapia (Oreochromis niloticus) were evaluated. Nile tilapia broodstock were fed diets containing 0.0, 2.5, and 5.0 g of Ascogen®/kg for five months. After this period, the eggs were collected and incubated. The offspring, at five days of age, were fed diets containing 0.0, 2.5, 5.0, and 7.5 g of Ascogen®/kg for 100 days. Analyses of digestive enzyme activity and the morphology of hepatic and intestinal tissues of juveniles were conducted. An interactive effect (p<0.05) between the diets of broodstock and offspring on trypsin activity was observed. The highest activity of this enzyme was recorded when diets containing 2.5 g/kg were used for broodstock and 7.5 g/kg for offspring. Juveniles from broodstock fed with 0.0 g/kg and offspring fed with 7.5 g/kg showed a significantly greater (p<0.05) height of enterocytes. Hepatic tissue was not influenced by the diets regarding its morphology. It is concluded that 7.5 g/kg of Ascogen® in offspring's diet promotes alterations in intestinal morphology in terms of enterocyte height. Under this condition, when associated with 2.5 g/kg of Ascogen® for broodstock, it enhances trypsin activity in the offspring.

The Effect of Silver Nanoparticles on the Digestive System, Gonad Morphology, and Physiology of Butterfly Splitfin (Ameca splendens).

The aim of this study was to determine the effects of silver nanoparticles (AgNPs) on the morphology and enzymatic activity of butterfly splitfin (Ameca splendens). Individuals of both sexes, aged about five months, were exposed to AgNPs at concentrations of 0 (control group), 0.01, 0.1, and 1.0 mg/dm3 for 42 days. On the last day of the experiment, the fish were euthanized, subjected to standard histological processing (anterior intestine, liver, and gonads), and analysed for digestive enzyme activity in the anterior intestine and oxidative stress markers in the liver. Fish in the AgNP 0.01 and 0.1 groups had the lowest anterior intestinal fold and enterocyte height. However, there were no statistically significant changes in the digestive enzyme activity in the anterior intestine. Analysis of enzymatic activity in the liver showed an increase in superoxide dismutase activity in fish in the AgNP 0.1 group. Histological analyses showed that AgNPs inhibited meiotic divisions at prophase I in a non-linear manner in ovaries and testes. In the AgNP 0.1 and 1.0 groups, the area occupied by spermatocytes was lower compared to the other groups. These results indicate that exposure to AgNPs may lead to disturbances in morphology and enzymatic activity in the liver and intestine and may lead to disruption of reproduction in populations.

Aquatic product hydrolysates increase rearing performance in red seabream (Pagrus major), fed a low fish meal diet, in both controlled and stressed conditions: From growth to stress responses

Although aquaculture industry has made great efforts to reduce the levels of fish meal (FM) in aquaculture feeds, further efforts and investigations are still needed to increase aquaculture production, which has more than tripled in the last two decades. This study was implemented to Six replicate groups of fish (24.6 ± 0.1 g) were fed one of the experimental diets to apparent satiety twice daily for 15 weeks; half of them were subjected to a daily net chasing stress for 1 min in the morning, 1 h before feeding. At the end of the feeding trial, fish were challenged with Edwarselia tarda injection. LFM diet resulted in comparable growth and feed efficiency performance to HFM group. However, significant impairments were observed in apparent digestibility coefficients, condition factor, hematocrit and serum super oxide dismutase activity. Fish fed LFM showed much lower resistance to E. tarda challenge. Both TH and SH resulted in enhanced fish nutritional and health performance with significant improvements in growth performance, feed efficiencies, digestibility, serum non-specific immunity and gut morphometric parameters. Fish fed TH and SH also exhibited the highest survival after E. tarda challenge. Principal component analysis (PCA) showed significant differences between stress and dietary groups for dimension 1 (33.3% of the variability), which was mostly characterized by growth and health variables. SH and TH coordinates were significantly higher on dimension 1 compared to HFM and LFM ones. Daily repeated stress affected most of measured performance parameters of all dietary groups with very few interactions. The stressed fish groups fed TH or SH showed lower cortisol levels compared to those fed HFM and LFM (p < 0.01). Strong correlations were observed between feed efficiency and fish gut morphometrics as quantified by villi length, enterocyte height and goblet cell density. Dietary supplementation of aquatic protein hydrolysates such as TH and SH appeared to be essential for maintaining good fish performance when they were subjected to a daily husbandry stressor or to an infectious challenge.

Seasonal flexibility of the gut structure and physiology in Eremias multiocellata.

Although gut seasonal plasticity has been extensively reported, studies on physiological flexibility, such as water-salt transportation and motility in reptiles, are limited. Therefore, this study investigated the intestinal histology and gene expression involved in water-salt transport (AQP1, AQP3, NCC, and NKCC2) and motility regulation (nNOS, CHRM2, and ADRB2) in desert-dwelling Eremias multiocellata during winter (hibernating period) and summer (active period). The results showed that mucosal thickness, the villus width and height, the enterocyte height of the small intestine, and the mucosal and submucosal thicknesses of the large intestine were greater in winter than in summer. However, submucosal thickness of the small intestine and muscularis thickness of the large intestine were lower in winter than in summer. Furthermore, AQP1, AQP3, NCC, nNOS, CHRM2, and ADRB2 expressions in the small intestine were higher in winter than in summer; AQP1, AQP3, and nNOS expressions in the large intestine were lower in winter than in summer, with the upregulation of NCC and CHRM2 expressions; no significant seasonal differences were found in intestinal NKCC2 expression. These results suggest that (i) intestinal water-salt transport activity is flexible during seasonal changes where AQP1, AQP3 and NCC play a vital role, (ii) the intestinal motilities are attenuated through the concerted regulation of nNOS, CHRM2, and ADRB2, and (iii) the physiological flexibility of the small and large intestine may be discrepant due to their functional differences. This study reveals the intestinal regulation and adaptation mechanisms in E. multiocellata in response to the hibernation season.

Dietary inosine monophosphate improved growth, feed utilization, blood biochemical characteristics, and intestinal histo-morphology of slow growing golden mahseer (Tor putitora)

A 10-week long feeding trial was run to determine the effects of inosine monophosphate (IMP) as functional nutrient on growth, feed utilization, haemato-immunological characteristics, and intestinal morphology of juvenile T. putitora. Casein and fishmeal based semi-purified basal diet (control) was formulated to contain 40 % protein and 10 % lipid. Four levels of IMP nucleotide viz., 0.05 %, 0.1 %, 0.2 % and 0.4 % were added to the basal diet for diet groups IMP-0.05, IMP-0.1, IMP-0.2 and IMP-0.4, respectively. Each diet was assigned randomly to triplicate groups of fish occupying an initial average weight of 9.1 ± 0.02 g. The results indicated that dietary IMP significantly enhanced the growth performance of fish and fish fed IMP-0.05 and IMP-0.1 diets showed significantly highest values. Compared to the control, IMP-0.05 diet group showed significantly lower feed conversion ratio, while protein efficiency ratio (PER) was significantly higher in fish fed IMP-0.05 and IMP-0.1 diet groups followed by IMP-0.2 diet group. Control and IMP-0.4 groups showed significantly lower PER. Higher IMP included group (IMP-0.4) showed significantly lower feed intake value. Again, the whole-body lipid content was significantly influenced by dietary IMP inclusion among major whole-body nutrients. Significantly reduced plasma glucose, bilirubin, and alanine aminotransferase level accounted for in IMP supplemented units compared to the control. IMP supplementation also significantly improved total immunoglobulin and hematocrit content. Supplementation of IMP significantly increased and decreased peroxidase and catalase activity, respectively. Fish fed 0.05–0.15 % IMP supplemented diets showed significant improvement in fold height (hF), enterocyte height (hE) and microvillus height (hMV) of anterior intestine compared to the control. In posterior intestine, similar supplementation level of IMP (0.05–0.15 %) showed significant improvement in hE and hMV, while hF showed numerically higher values except in fish fed IMP-0.05 diet group. Based on the current experimental conditions, a dietary IMP of 0.05 % resulted in improved outcomes in the majority of the fish growth and health performance indicators. However, quadratic regression analysis of all the significantly influenced fish performance parameters disclosed that the optimal level of dietary IMP was 0.17 % and this is also consistent with the majority of fish growth and health performance measures.

Exploring the multimodal role of Cnicus benedictus extract in the modulation of growth, hematobiochemical, histopathological, antioxidative performance, and immune-related gene expression of Oreochromis niloticus challenged with Aeromonas hydrophila

This study explored the growth efficiency and the intracellular pathways by which Cnicus benedictus extract (CBE) acts. It investigated the antioxidant effects and efficacy of CBE as a fish supplement in attenuation of Aeromonas hydrophila in Oreochromis niloticus fish. Mono-sex Nile tilapia fish (n = 225) were randomly allocated to five groups in triplicate aquaria (n = 3 tanks per group, 15 fish per tank, with 120 L of water per tank) with a daily water exchange rate of 20%. After adaption for 2 weeks and body weight measuring, the experimental groups were fed isonitrogenous and isocaloric diets with different dosages of the ethanolic extract of C. benedictus for 10 weeks. The five groups were identified as the control group (CBE0.0), which was fed on the basal diet, while the second (CBE0.1), the third (CBE0.2), the fourth (CBE0.4), and the fifth (CBE0.6) groups were fed the basal diet supplemented with 0.1%, 0.2%, 0.4%, and 0.6% of C. benedictus extract, respectively. After the 10-week feeding trial was completed, the fish were inoculated with the PCR-identified pathogenic A. hydrophila in a challenge trial which lasted 15 days. A. hydrophila, one of the septicemic bacteria, causes severe economic losses, high mortality rates, and hemorrhages in Nile tilapia and other cultured freshwater fishes worldwide. The CBE was found to significantly increase the body mass, weight gain, and the specific growth rate, as well as the protein efficiency ratio of the fish. Increased survival percentage, accompanied by post challenge lymphocytosis with decreased liver enzyme levels, increased total protein, and improved kidney function markers were also seen. Additionally, CBE supplementation showed significant increases in phagocytic activity, phagocytic index, and lysosomal activity post challenge, accompanied by increases in antioxidant activity and the mRNA expression of cytokines genes hsp70 and tlr7 mRNA. The desirable effects of CBE treatment were confirmed by a histopathological examination of the height of intestinal villi and enterocytes lining the middle intestine and increases in the size of liver cells. We conclude that CBE increases the growth performance and modulates the antioxidant, inflammatory, stress, and immune-related genes in Nile tilapia. Moreover, the dietary inclusion of 0.42–0.47% CBE showed a better protective effect with the A. hydrophila challenge.

Replacing fishmeal protein with blended alternatives alters growth, feed utilization, protein deposition and gut micromorphology of humpback grouper, Cromileptes altivelis

This research aims to investigate the effects of different dietary fishmeal (FM) protein replacements by blended alternative proteins on growth, feed utilization, protein deposition and gut micromorphology of humpback grouper, Cromileptes altivelis. Five isoenergetic (14.23 kJ/g, dry matter), isoproteic (48.91 %, dry matter) and isolipidic (10 %, dry matter) experimental diets were formulated, with 0 % (R0), 21 % (R21), 42 % (R42), 63 % (R63) and 84 % (R84) FM protein being replaced by blended alternative proteins which consisted of soybean protein isolate (SPI), poultry by-product meal (PBM), hemoglobin powder (HP). Triplicate groups of fish (mean initial body weight: 6.50 ± 0.17 g, 12 fish/group) were manually fed each diet to apparent satiety twice daily for 8 weeks. Results showed that different FM protein replacements by the blended proteins significantly influenced percentage weight gain (WG %), daily feed intake (DFI), feed conversion ratio (FCR), protein efficiency ratio (PER) and protein productive value (PPV) of fish. Fish fed R84 had the lowest WG %, PER and PPV among all experimental groups. The quadratic broken-line regression analysis of WG % indicated that the maximum FM protein replacement level by the blended proteins was 67.0 % of dry matter. Fish fed R84 had lower expression of growth hormone (GH), growth hormone receptor (GHR), insulin like growth factor-I (IGF-1), target of rapamycin (TOR) and S6 kinase 1 (S6K1) than fish fed other diets. General control nonderepressible 2 (GCN2) and CCAAT enhancer binding protein β (C/EBPβ) showed higher expression in the R84 group compared to those in other groups. The villous height (hV), villous width (wV) as well as enterocyte height (hE) of gut were also affected by different experimental treatments, with the R84 group having lower values compared to other groups. Generally, 67.0 % of dietary FM protein could be replaced by a blend of SPI, PBM and HP proteins without negatively influencing the WG % of humpback grouper.

Effects of dietary nucleotides on growth performance, immune response, intestinal morphology and disease resistance of juvenile largemouth bass, Micropterus salmoides.

An 8 week feeding trial was carried out to investigate the effects of dietary nucleotides on growth performance, intestinal morphology, immune response and disease resistance of juvenile largemouth bass, Micropterus salmoides. Five grades of dietary nucleotide levels were designed as 0, 0.2, 0.4, 0.8 and 1.2g kg-1 , respectively. Each group had 3 replicates, with 40 fish in each replicate. After the feeding experiment, 15 fish from each tank were infected with Aeromonas hydrophila for 14 days. The results indicated that fish fed the diets containing 0.4, 0.8 and 1.2g kg-1 nucleotides had higher growth performance and feed utilization than those fed the control diet. Nonetheless, there were no significant differences in survival between all the groups, although fish fed the diets with all-level nucleotides obtained higher survival than those fed the control diet. Dietary nucleotides significantly affected the superoxide dismutase, acid phosphatase and catalase activities in serum but not the malondialdehyde content. Fish fed the 0.4g kg-1 nucleotide diets had the highest fold height, enterocyte height and muscular layer thickness significantly. The average mortality of largemouth bass infected with A.hydrophila was significantly influenced by dietary nucleotides. The mortality was significantly higher in the control group (91.11%) and 0.02% nucleotide group (73.11%) followed by the other groups and lowest in the 0.8g kg-1 nucleotide group. In summary, dietary 0.4-0.8g kg-1 nucleotides promoted growth performance, enhanced immunity and improved intestinal morphology and disease resistance of largemouth bass.

Intestinal health in Atlantic salmon post-smolt (Salmo salar) when fed low- and high HUFA diets

It is well established that farmed Atlantic salmon (Salmo salar) need n3-highly unsaturated fatty acids (HUFA) in their diet to thrive and grow. However, the biological functions to the individual HUFAs may differ, implying that future supplementation could require fixed ratios for maximum benefit. The intestinal barrier is essential to fish health, and any disruption of the barrier can have detrimental effects. The current experiment was designed to examine the response of the intestinal hindgut when fed a low HUFA diet with 8.5 g/kg EPA + DHA (4.5% total fatty acid) or two high HUFA diets, with either high DHA (28.7 g/kg and 5.9% total fatty acid) or high EPA (25 g/kg and 14.2% total fatty acid). The diets were fed to Atlantic salmon post-smolt over 10 weeks and thereafter exposed to 3 weeks of chronic stress. After 10 weeks of feeding there were no differences in intestinal permeability and integrity, but intestinal morphology indicated increased intestinal health in the high EPA group. Gene expression also suggest that fish fed the high EPA diet had more regulation of pathways related to protein turnover compared to the high DHA fed fish. There was also indication of lower energy utilization in the low HUFA fed fish than high HUFA. Subjecting fish to 3 weeks of chronic stress led to a reduction in transepithelial resistance, increased ion flux and active l-lysine transport across the intestinal barrier in addition to a decrease in mucosal fold, enterocyte height and supranuclear vacuole density and an increase in thickness of the intestinal muscularis. After stress, the low HUFA group showed signs of inflammation with increased infiltration of MHCII positive cells. Gene expression also showed that low HUFA fed fish had a lower response to chronic stress compared to the high HUFA groups. Comparing fish fed either high DHA or EPA exposed to chronic stress showed few physical effects, but a lower density of supranuclear vacuoles and upregulation in immune-related gene expression indicate inflammation in the high DHA group.

Probiotic supplementations improve growth, water quality, hematology, gut microbiota and intestinal morphology of Nile tilapia

A 75-day long experiment was performed to evaluate the effects of probiotic supplementations on rearing water quality, hematology, intestinal morphology, and gut bacterial load of Nile tilapia, Oreochromis niloticus. Fifteen ponds were used for 5 treatments with 3 replications, and 400 fingerlings per pond were fed with pre-starter feed twice a day at 5–8% of body weight. First treatment (T1) was supplemented with the soil probiotic Super PS/ week, T2 was designed to add gut probiotic Zymetin with feed, T3 contained half of the recommended doses of soil, gut, and water probiotics pH FIXER, T4 was planned to supplement with pH FIXER/ week, and no probiotic was used in T5 (control). Growth parameters (net weight gain, weight gain (%) and specific growth rate (%), SGR), survival, feed utilization (feed conversion ratio, FCR and feed conversion efficiency, FCE); water quality (dissolved oxygen, DO, free ammonia, temperature, alkalinity and pH), hematological parameters (RBC, WBC, hemoglobin, glucose, mean corpuscular hemoglobin, MCH), gut bacterial load and intestinal histomorphology (villi length, and enterocyte height) were analyzed fortnightly by sacrificing 3 fish/ treatment. Significant improvements in water qualities, growth performance, feed utilization, hematological parameters, intestinal microbial load and morphology were found with probiotic supplemented treatments than the control group where supplementation of gut probiotic (T2) and combination of soil, gut and water probiotics (T3) significantly augmented growth performance and feed utilization with improved gut microbiota and intestinal morphology. Hence, the findings recommended probiotic supplementation as an eco-friendly health management approach for tilapia aquaculture.

Using the nematode Panagrolaimus sp. in larval rearing of longfin yellowtail Seriola rivoliana: preliminary results

The potential of Panagrolaimus sp. nematode as a live prey was assessed in longfin yellowtail Seriola rivoliana larval rearing. Larvae were reared from 3-11 days post-hatching (dph) in a 2000 L tank and fed on copepods and rotifers. On 12 dph, larvae were transferred to eight 200 L tanks at a density of 12 larvae L -1 to start the feeding trial, consisting of two treatments ( Artemia or nematodes) using four replicates each. Rotifers were offered on 12 dph with a co-feeding from 14 to 16 dph (rotifer/enriched Artemia or rotifer/nematode). Only Artemia or nematodes were supplied from 17 to 19 dph. Feeding incidence was 80-90% on 14 dph, but more larvae were capturing rotifers than Artemia or nematodes. Artemia consumption increased more than nematodes at 19 dph, though it was not significantly different. Significantly lower enterocyte and villus heights in the posterior intestine were observed at 19 dph in larvae fed on nematodes but only in enterocyte height in the anterior one. No significant differences were observed between treatments in total larval length and body depth on 16 dph, but a significantly higher total length in the nematode one was present on 19 dph. A significantly higher survival was observed in treatment Artemia compared to nematodes. These preliminary results showed a lower nutritional condition in larvae fed nematodes; however, technical improvements need to be performed to increase Panagrolaimus sp. availability to larvae in the water column.

Beneficial effects of dietary papain supplementation in juvenile sterlet (Acipenser ruthenus): Growth, intestinal topography, digestive enzymes, antioxidant response, immune response, and response to a challenge test

Juvenile sterlet (Acipenser ruthenus) were fed commercial feed (group C) and experimental feed supplemented with papain in doses of 10 g kg−1 feed (P1) and 20 g kg−1 feed (P2) for eight weeks. Growth, digestive enzyme activity, immunity parameters, pathological changes of the liver and intestine, proximate body composition, and oxidative response were assayed. A challenge test with Yersinia ruckeri was also performed. The final body weights of groups P1 (107.07 ± 7.66 g) and P2 (111.98 ± 1.93 g) were significantly (P < 0.05) higher compared to the control group (99.73 ± 2.71 g). The height of the intestinal enterocytes was the greatest in group P2, and the highest supranuclear surface of the intestinal enterocytes was noted in groups P1 and P2. The activities of α-amylase, trypsin, lipase, and leucine aminopeptidase were significantly (P < 0.05) higher in the posterior intestine of the fish from group P2 than in the other dietary treatment groups. Ceruloplasmin, total immunoglobulin (Ig), the metabolic activity of splenic macrophages (PMA), and the potential killing activity of splenic phagocytes (PKA) were significantly higher in groups P1 and P2 compared with the control group. The proliferative activities of spleen T and B-lymphocytes were significantly (P < 0.05) higher in group P2 in comparison to the control group and group P1. Total antioxidant status (TAS), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were significantly increased in groups P1 and P2 compared with the control group. The glutathione reductase (GLURED) activities decreased significantly (P < 0.05) with increasing levels of papain supplementation. Furthermore, during the challenge test, fish survival was significantly higher in groups fed feed supplemented with papain. Finally, the current study indicated that supplementing feed with doses of 10 g and/or 20 g papain kg−1 for a period of 56-days improved growth efficiency and feed utilization and also stimulated immunity in aquaculture conditions.

Effects of fermented soybean meal and guanosine 5'-monophosphate on growth, intestinal health and anti-stress capability of Penaeus vannamei in low fish meal diet

Substitution of fishmeal by plant protein source has been one of the most concerned issues in aquaculture. The present study aimed to evaluate the replacement of fishmeal by fermented soybean meal (FSM) and supplementation of nucleotide, guanosine 5′-monophosphate (5′-GMP), on growth, intestinal health and anti-stress capability in Penaeus vannamei. Six diets were formulated to contain three replacement levels of fish meal by FSM (0, 22.22% and 44.44%) with or without 5′-GMP (0.1%). The feeding trial lasted for 8 weeks, followed by the hypoxia exposure. The results indicated that 44.44% of fishmeal substituted by FSM did not have negative effects on growth and digestive enzymes activities in shrimp, while it significantly affected intestinal micromorphology by decreasing fold height, enterocyte height and microvillus height. 22.22% of Fishmeal substituted by FSM had higher genes expression of target of tor, s6k and 4ebp1 suggesting the potential improvement in growth. Application of FSM influenced intestinal microbiota of shrimp with the changes in microbiota composition, community diversity and richness. Metabolites and enzymes associated with stress response including MDA, LD, SOD, T-AOC, GSH and GSH-PX were all markedly increased after hypoxia stimulus, and SOD, T-AOC and GSH-PX was significant higher in the shrimps fed without 5′-GMP in high fishmeal diet. Lgbp and hsp70 mRNA level were also higher in the shrimp after hypoxia stimulus especially fed with 5′-GMP in low fishmeal diet, while sp and pe were lower expressed in the shrimps after hypoxia stimulus. Finally, our results determined that FSM had a fishmeal sparing effect for the diet of P. vannamei, and the supplementation of 5′-GMP in the diet slightly benefited growth, gut health and anti-stress capacity for P. vannamei.

Mucosal barrier status in Atlantic salmon fed marine or plant-based diets supplemented with probiotics

Feed ingredients and additives significantly affect the mucosal health of fish. A 3 × 2 factorial experiment was conducted to investigate the mucosal health of Atlantic salmon (Salmo salar) fed three basal feeds (namely, BG1, BG5 and BG2; marine-, plant-, and soybean meal-based feeds, respectively) or the basal feeds with (+) or without (÷) probiotics, Lactobacillus fermentum and Lactobacillus plantarum. Six diets were fed to fish distributed into 12 tanks (approximately 43 fish/tank). The average start weight of the experimental fish was about 122.6 g. After 38-days of feeding, the dorsal skin, gills and distal intestine were obtained for analysing histomorphometry and mucus-related genes. Digesta were also collected to study short chain fatty acids (SCFAs).Fish fed BG2 had significantly higher number of mucous cells/μm2 skin epithelium (SNE) than those fed BG1 and BG5. Addition of probiotics significantly increased SNE in BG5+ and BG2+ group compared to BG1÷ group. Similarly, the area and number of mucous cells/μm2 gill epithelium (GME and GNE) were significantly higher in BG2 group, followed by BG5 and BG1 fish groups. Probiotics significantly increased GME and GNE in all feed types. Concerning intestine, villi height (VH) and enterocyte height (EH) were significantly higher for BG1 group, followed by BG5 and BG2 groups. Compared to fish offered BG2, fish fed BG1 had significantly wider villi (VW) and narrower lamina propria (LPW). The number of mucous cells (NM) and intraepithelial lymphocytes (IEL) in the intestine were significantly higher in BG2 fed fish than those offered BG5 and BG1. The indices VH, VW, EH, and IEL were not affected by probiotics. Although higher NM and IEL were observed in BG2÷ fish compared to those fed the other two diets, probiotics reduced NM and IEL. Fish fed BG2÷ showed symptoms of inflammation, including disappearance of supranuclear vacuoles (SNV). Probiotics improved VH, significantly reduced LPW and aided in the reappearance of SNV in BG2+ fed fish. Some of the gene expression data supported histological findings; notably, levels of muc5ac1 in the skin and defensin3 and cathelcidin1 in the intestine were correlated with histology data. Moreover, the total SCFA concentration was significantly affected by feed ingredients. Only acetoacetic acid was affected by both factors.Our findings suggest that feed ingredients can significantly alter the mucosal protective barrier of the organs. Supplementation of probiotics alleviated the inflammatory responses and activated selected innate immune defence molecules, without affecting growth. The positive effect of the probiotics was similar regardless of the feed ingredients, suggesting that these probiotics can be utilized as immune regulators to evoke favourable responses on the skin, gills and intestine.

Histological structure of the digestive tract and digestive enzymatic activity of juvenile Pacific seahorse (Hippocampus ingens)

The histological structure, histochemical features, and enzymatic activity of the digestive tract of juvenile Pacific seahorse (Hippocampus ingens) are described to provide information during the cultivation of this species. Serial histological sections were stained with either hematoxylin-eosin, alcian blue-PAS, toluidine blue, Sudan black, Masson's trichome, and ninhydrin-Schiff to describe the general features and the presence of glycogen, mucopolysaccharides, lipids, muscle layers, and proteins, respectively. The enterocytes height and the mucosal villi height in the esophagus and intestines were measured. Additionally, the digestive enzymes trypsin, chymotrypsin, lipase, amylase, aminopeptidase, acid phosphatase, and alkaline phosphatase activities were recorded. The esophagus showed two distinctive regions, the anterior with numerous mucous cells secreting acid mucins and the posterior with longitudinal folds and no mucous cells. The intestine was differentiated into three regions. The anterior showed goblet cells secreting acid and neutral mucins, while the middle and posterior regions presented goblet cells secreting only acid mucins. The activity of aminopeptidase, chymotrypsin, and amylase showed low levels, while the trypsin and acid phosphatase activity levels were intermediate. Lipase and alkaline phosphatase showed the highest activities. The results point that juvenile H. ingens presents a digestive structure similar to other teleost species. The high levels of lipase suggest that juvenile H. ingens have high requirements for lipids during this stage.

A Solid-State Fermentation (SSF) supplement improved performance, digestive function and gut ultrastructure of rainbow trout (Oncorhynchus mykiss) fed plant protein diets containing yellow lupin meal

A nutritional investigation was conducted to determine whether growth performance, feed efficiency and midgut morphology of rainbow trout (Oncorhynchus mykiss) is affected by United Kingdom cultivars of Yellow Lupin (Control, Y) (LC) compared to the addition of a commercial solid-state fermentation product (SSF) in separate dietary treatments 0.1 and 0.5% (LS0.1 and LS0.5, respectively). At the end of feeding trial, LC- and LS0.1-fed fish did not differ from one another, whilst significant improvement was observed in LS0.5 fed fish (P < 0.05). Apparent digestibility of crude protein and crude fibre were significantly higher in fish fed LS0.1 and LS0.5 than LC. No significant differences (P < 0.05) in Haemoglobin (Hb) concentrations were observed among dietary treatments. Fish fed the 0.1% SSF inclusion exhibited significantly (P < 0.001) higher haematocrit (Hct) concentration than all other treatments. Significantly (P < 0.005) higher serum glucose levels were observed in FMC fed fish compared to fish fed LC and LS0.1, whilst elevation was also observed in LS0.5 over LC and LS0.1. Activity of serum lysozyme was significantly (P < 0.05) higher in the LS0.5 treatment compared to LC, S0.1 and FMC groups. Fish fed 0.5% SSF were observed to have a significant (P < 0.05) reduction in goblet cell counts (GC) compared to those fed LC and LS0.1.). Median enterocyte height (EH) of LS0.1 and LS0.5 fed fish did not differ from one another but were both significantly greater than LC fed fish. Mean microvilli length (MVL), diameter (MVD) and enterocyte apical area (EAA) did not differ significantly between dietary treatments (P > 0.05). Fish fed 0.5% SSF displayed a higher microvillar percentage coverage (MVCV) compared to fish fed LC and LS0.1. Total alkaline protease (TAP), trypsin and chymotrypsin activities in the digesta of fish were unaffected by dietary treatment (P > 0.05). Activity of alkaline phosphatase (ALP) in digesta was significantly (P < 0.05) higher in SSF treatments than LC. Activity of L-leucine aminopeptidase (LAP) in digesta was marginally significantly (P = 0.045) higher in LS0.1 SSF fed fish than LC fed fish. Activity of LAP was also significantly higher in LS0.5 fed fish than LC fed fish.

Singular effects of Bacillus subtilis C-3102 or Saccharomyces cerevisiae type 1 on the growth, gut morphology, immunity, and stress resistance of red sea bream (Pagrus major)

Abstract The beneficial effects of Bacillus subtilis C-3102 and Saccharomyces cerevisiae type 1 were tested in red sea bream (Pagrus major) feeds. A basal diet (control) and two other diets were prepared by supplementation with B. subtilis C-3102 (PB) or S. cerevisiae type 1 (PY). After 60 days, both probiotic-supplemented groups exhibited significant enhancement in growth performance, the protein efficiency ratio (PER), and digestive enzyme secretion (protease and amylase) compared to the control group (P&lt;0.05). The anterior, middle, and posterior parts of the intestines exhibited significantly increased values of intestinal fold height (hF), enterocyte height (hE), and microvillus height (hMV) in fish fed PB- or PY-supplemented diets (P&lt;0.05). Serum peroxidase, anti-protease, and bactericidal activities were enhanced significantly in both probiotic-treated groups compared to the control group (P&lt;0.05). Serum and mucus lysozyme activities improved significantly in the PB group compared to the control group (P&lt;0.05). Catalase activity was also significantly decreased in both probiotic groups, with relatively lower activity observed in the PY group (P&lt;0.05). Both probiotic groups showed considerably increased tolerance to freshwater exposure (P&lt;0.05). In conclusion, B. subtilis C-3102 and S. cerevisiae type 1 can be used as functional probiotics to enhance the growth performance, digestion capacity, gut morphology, immune response, and stress resistance of the red sea bream with relatively higher efficiency by B. subtilis C-3102.

Effects of Atlantic salmon (Salmo salar) fed low- and high HUFA diets on growth and midgut intestinal health

For a rapidly developing aquaculture industry where availability of raw materials for diet formulation are quickly changing it is fundamental to define what the dietary needs and benefits are. In farming of Atlantic salmon (Salmo salar), highly unsaturated fatty acids (HUFA) are known to be essential and a minimum dietary inclusion is needed. The aim of this study has been to map Atlantic salmon performance and midgut health towards dietary HUFAs under normal and challenging condition. Atlantic salmon post-smolt at 150 g were fed four experimental diets over a feeding period of 10 weeks up to a final weight of 377 g followed by three weeks of unpredictable chronic stress (UCS). The diets varied in their HUFA level, with either 28.7 g/kg DHA (HDHA), 25 g/kg EPA (HEPA), 21.3 g/kg ARA (HARA) or 8.5 g/kg EPA + DHA (LHUFA). After the feeding period all fish had more than doubled their weight and fish fed HARA showed a significant lower specific growth rate compared to all other diets. Diets had little effect on intestinal morphology, barrier and transport function. Intestinal polar lipid composition suggested higher lipid metabolism in fish feed LHUFA and transcriptome analysis confirm upregulated lipid metabolism and downregulated energy turn over. Comparing transcriptome profiles from HDHA to HEPA, more upregulated pathways are seen in fish fed HEPA, including metabolism and immunity. The fish feed HARA had downregulated turn-over and metabolism compared to fish fed HEPA. The UCS period resulted in zero growth and lower enterocyte height in all diet groups, and the intestinal barrier was reduced in the paracellular permeability to mannitol. Contradictory to previous studies, fish fed HDHA and HEPA responded to UCS with enhanced intestinal resistance. UCS also resulted in impaired intestinal transport by elevated ion flux and epithelial electrochemical gradient in fish fed LHUFA. Transcriptome pathway analysis indicated more cell turn over and lipid metabolism in LHUFA and HDHA. In conclusion, a low HUFA diet with 8.5 g/kg DHA + EPA can sustain growth and intestinal health under controlled condition, but the health is impaired after three weeks of chronic stress. Decreasing the n6/n3 ratio by increasing levels of EPA and DHA strengthens intestinal barrier in response to chronic stress. Increasing the ARA to HUFA ratio may have a negative effect on growth, but not on intestinal health.