Intestinal Digestive Enzyme Activities Research Articles

Effects of Different Viscous Guar Gums on Growth, Apparent Nutrient Digestibility, Intestinal Development and Morphology in Juvenile Largemouth Bass, Micropterus salmoides.

An 8-week feeding trial was conducted to investigate the effects of different viscous guar gums on the growth performance, apparent nutrient digestibility, intestinal development and morphology of juvenile largemouth bass. Four isoproteic and isolipidic diets (crude protein 42.5%, crude lipid 13.7%) were formulated to contain 8% cellulose (Control group), 8% low viscous guar gum with 2,500 mPa s (Lvs-GG group), 8% medium viscous guar gum with 5,200 mPa s (Mvs-GG group) and 8% high viscous guar gum with 6,000 mPa s (Hvs-GG group), respectively. Each diet was fed to quadruplicate groups of 40 fish (6.00 ± 0.01 g) per repetition. Dietary guar gum inclusion significantly decreased the weight gain rate, specific growth rate, protein efficiency ratio, protein productive value and lipid deposition rate, and these parameters decreased considerably with increasing guar gum viscous and were lowest in the Hvs-GG group. Dietary guar gum inclusion significantly decreased the apparent digestibility of dry matter, crude protein and crude lipid, and these parameters decreased considerably with increasing guar gum viscous and were lowest in the Hvs-GG group. Intestinal protease, lipase and creatine kinase activities in the guar gum groups were significantly lower than those in the control group, and intestinal protease and lipase activities decreased considerably with increased guar gum viscous. Intestinal alkaline phosphatase activity in the Hvs-GG group and intestinal Na+/K+-ATPase activity in the Mvs-GG and Hvs-GG groups were significantly lower than those in the Lvs-GG and control groups. Serum high-density lipoprotein, total cholesterol and triglyceride concentrations and superoxide dismutase activity in the guar gum groups were significantly lower than those in the control group. Intestinal villus height and muscular thickness in the guar gum groups were considerably higher than those in the control group, whereas the goblet cell relative number in the Mvs-GG and Hvs-GG groups and the microvillus height in the Lvs-GG and Hvs-GG groups were significantly lower than those in the control group. The expression level of IGF-1 in the guar gum groups and the expression level of GLP-2 in the Mvs-GG and Hvs-GG groups were significantly higher than those in the control group. These results indicated that guar gum diets adversely affected intestinal morphology, decreased intestinal digestive and absorptive enzyme activities, and caused poor nutrient digestibility and growth performance in juvenile largemouth bass. Moreover, the adverse effects of guar gum are closely related to its viscous, and high viscous guar gum produces more extreme negative impacts on juvenile largemouth bass.

Effects of Clostridium autoethanogenum protein as substitute for dietary fishmeal on the growth, feed utilization, intestinal health and muscle quality of large yellow croaker Larimichthys crocea

A 90-day feeding trial was conducted to evaluate the effects of Clostridium autoethanogenum protein (CAP) replacing dietary fishmeal on growth, feed utilization, intestinal health and muscle quality of large yellow croaker (Initial body weight: 189.9 ± 1.11 g). The control diet (CAP0) contains 62% fishmeal, which was replaced with CAP at 15% (CAP15), 30% (CAP30), 45% (CAP45), 60% (CAP60), 75% (CAP75) and 100% (CAP100), respectively. Results showed that the weight gain rate, protein efficiency ratio, feed intake, condition factor and intestinal villus height of fish significantly decreased when the replacement level of dietary fishmeal by CAP exceeded 30%, while feed conversion ratio increased significantly in the CAP60, CAP75 and CAP100 treatments (P < 0.05). Increasing replacement levels of dietary fishmeal by CAP linearly decreased the activities of intestinal digestive and absorptive enzymes (P < 0.05). In addition, the mRNA expression level of intestinal peptide transporter 1 and nuclear factor κB genes was up-regulated with increasing dietary CAP level, while the intestinal peptide transporter 2, occludin-like and interleukin 10 genes was down-regulated (P < 0.05). The muscle amino acid compositions and skin color were not significantly affected by dietary CAP supplementation. Compared with those in the CAP0 group, fish in the CAP75 and CAP100 group showed a significantly lower muscle firmness, water holding capacity and myofiber diameter, and a higher myofiber density (P < 0.05). The mRNA expression of myogenic differentiation, myogenin, myogenic factor 5 and paired box 7 genes was significantly up-regulated, while the expression of myostatin gene was significantly down-regulated in the muscle of fish in the CAP75 and CAP100 group (P < 0.05). In conclusion, CAP can replace up to 30% of dietary fishmeal protein for large yellow croaker without negative effects on the growth, feed utilization, intestinal health and muscle quality.

Modulation of dietary protein to lipid ratios for gilthead seabream on-growing during summer temperature conditions

Gilthead seabream (Sparus aurata) tend to increase fat deposition during summer farming conditions in the Mediterranean, which may negatively affect productive performance and consumers’ quality perception of the final product. Therefore, this study evaluated the impacts of protein to lipid ratios in low fishmeal/fish oil diets on growth performance, body composition, feed conversion and nutrient utilization of seabream on-grown during summer temperature conditions. The experimental diets contained low levels of fishmeal, fish oil, and crude protein (39%), differing in crude lipid content: 16% (MF diet) or 12% (LF diet). A growth trial was performed with seabream (initial weight: 100 ± 7 g) from August to October (water temperature: 23.1 ± 2.2 ºC). A digestibility trial was also performed (at 23 ºC). Key performance indicators, whole-body composition and activities of digestive enzymes were evaluated at the end of the experiment (64 days). Low dietary lipid levels negatively affected lipid, energy, and amino acid digestibility, and as a result, fish fed the LF diet presented higher nitrogen faecal losses. Still, the decrease in nutrient digestibility was not related to dietary effects on the digestive enzyme activities. The experimental diets did not compromise the activity of pancreatic, gastric, and intestinal digestive enzymes nor feed utilization, but a slight growth impairment was observed in fish fed the LF diet, probably due to the lower amino acid and lipid digestibility. However, a potential benefit of this dietary treatment towards reducing fat accumulation in seabream during summer was observed. Nevertheless, the environmental impact of the nitrogen losses during seabream on-growing should be considered when estimating the sustainability of the production. This study demonstrated that the optimisation of diet formulations should account for the environmental conditions, especially in Mediterranean aquaculture, so the economic and environmental impacts may be correctly evaluated towards a more sustainable fish production.

Condensed tannins increased intestinal permeability of Chinese seabass (Lateolabrax maculatus) based on microbiome-metabolomics analysis

Condensed tannins (CT) have been reported to induce intestinal injury of fish, whereas the injury mechanism is unclear. This study evaluated the effects of dietary grape seed CT on growth, intestinal permeability, tight junction structure, intestinal digestive and brush border enzyme activity, bacterial community and intestinal metabolites of Chinese seabass (Lateolabrax maculatus). A total of 640 fish were randomly distributed into 16 tanks with 4 tanks per group and 40 fish per tank. Four diets were formulated to contain 0 (CT0), 1 (CT1), 2 (CT2), and 2 g/kg of CT plus 4 g/kg of polyethylene glycol (PEG) (CT2 + PEG). PEG specifically binds with CT to neutralize CT activity. The experiment was arranged as complete randomized design. Fish were hand-fed to apparent satiation twice daily and the feeding trial lasted for 63 days. Fish fed CT2 had lower (P < 0.05) final body weight, weight gain rate, specific growth rate and feed intake, but higher (P < 0.05) serum diamine oxidase activity and endotoxin level than other diets. Tight junction structures in CT1 and CT2 showed varying degrees of ambiguity and damage. The trypsin activity ranked as CT0 > CT1 > CT2 (P < 0.05). Fish fed CT2 had lower (P < 0.05) activities of lipase, amylase and creatine kinase than other diets. Na+, K+-ATPase activity was lower (P < 0.05) in CT1 and CT2 than in CT0. All parameters were similar (P > 0.05) between CT0 and CT2 + PEG. Intestinal microbiota analysis showed that the abundances of Bacillus, Acinetobacter and Pseudomonas were decreased (P < 0.05) but Clostridium was increased (P < 0.05) as dietary CT increasing. Fish fed CT2 + PEG had higher (P < 0.05) abundances of Bacillus, Acinetobacter and Pseudomonas but lower (P < 0.05) Clostridium than those of fish fed CT2. Bacterial diversity measurements were not affected (P > 0.05) by dietary treatments. Metabolomics analysis indicated that CT altered the intestinal metabolomics profile of L. maculatus. The valeric acid was decreased (P < 0.05), but phenylacetic acid was increased (P < 0.05) as dietary CT increasing. Compared to CT0, CT2 had lower (P < 0.05) isobutyric acid but higher (P < 0.05) butyric acid and isovaleric acid. In conclusion, this study suggests association between reduced growth and increased intestinal permeability and varying intestinal bacterial microbiota and metabolites of L. maculatus. This study warns that dietary CT at 2 g/kg could induce intestinal injury, microecological imbalance and metabolic disorder of fish, and the resulting adverse effects may neutralize by applying polyethylene glycol in fish diets.

Dietary Supplementation of Nile Tilapia (Oreochromis niloticus) With Panax ginseng Essential Oil: Positive Impact on Animal Health and Productive Performance, and Mitigating Effects on Atrazine- Induced Toxicity

The present study assessed the impact of Panax ginseng essential oil (GEO) supplementation on physiological parameters related to productive performance and health status in Nile tilapia reared under standard conditions and exposed to a sub-lethal atrazine (ATZ) concentration. Fish were allocated into 6 groups: the control group was reared in clean water and fed with a commercial basal diet (CNT), two groups were fed with the basal diet supplemented with two different levels of GEO (GEO1 and GEO2, respectively), one group was intoxicated with 1/5 of ATZ 96-h lethal concentration 50 (1.39 mg/L) (ATZ group), and the remaining two groups were fed with the GEO-supplemented diets and concurrently exposed to 1.39 mg ATZ/L (GEO1+ATZ and GEO2+ATZ, respectively). The experiment lasted for 60 days. GEO supplementation exerted a significantly positive influence on fish growth, feed utilization, and hepatic antioxidant defense systems at both levels of supplementation. ATZ exposure significantly reduced fish survival rates and impaired fish growth and feed utilization, with the lowest final weights, weight gain, total feed intake, and the highest feed conversion ratio being recorded in the ATZ-intoxicated group. ATZ exposure caused significant changes in intestinal digestive enzyme activity (decreased lipase activity), hematological indices (decreased hemoglobin, packed cell volume, erythrocytes, and leukocytes), blood biochemical variables (decreased total proteins, albumin, globulins, and immunoglobulin M; increased total cholesterol, triglycerides, and cortisol), and hepatic oxidative/antioxidant indices (decreased glutathione level, superoxide dismutase and catalase enzyme activity and mRNA expression levels, and increased malondialdehyde content). Moreover, in the hepatic tissue of ATZ-intoxicated Nile tilapia, histopathological alterations and upregulated mRNA expression levels of stress- and apoptosis-related genes (Hsp70, caspase 3, and p53) were observed. GEO supplementation in ATZ-treated groups significantly attenuated the aforementioned negative effects, though some parameters did not reach the CNT values. These findings provide further and partly new evidence that sub-lethal ATZ toxicity induces reduced survivability, growth retardation, impaired digestive function, anemia, immunosuppression, hepatic oxidative stress damage, and overall increased stress level in Nile tilapia, and suggest that GEO supplementation may be useful for mitigating this toxicity and provide more general support to the productive performance and health status of this fish species.

Effects of BBR on growth performance, serum and hepatic biochemistry parameters, hepatic morphology and gene expression levels related to glucose metabolism in largemouth bass, Micropterus salmoides

An 8-week experiment was performed to investigate the effects of BBR on growth performance, hepatic glucose metabolism, antioxidant capacity, liver histology and intestinal digestive enzyme activity of largemouth bass. Fish (initial weight ≈122 g) were randomly allocated into 16 cages (280 L, 30 fish per tank) and fed four isonitrogenous and isolipidic diets containing 0, 0.5, 1 and 2 g/kg BBR respectively. The results indicated that diets with 1 and 2 g/kg BBR significantly promoted growth, decreased serum glucose, triglycerides (TG), total cholesterol (TC) and low-density lipoprotein cholesterol but increased serum high-density lipoprotein cholesterol (p < 0.05). The application of BBR significantly decreased hepatic alanine aminotransferase, TG and TC but increased hepatic superoxide dismutase and catalase (p < 0.05). Diets with 1 and 2 g/kg BBR significantly decreased hepatic malondialdehyde, aspartate aminotransferase and hepatic glycogen but increased intestinal farnesoid X receptor and fibroblast growth factor-19 expression and dramatically altered its downstream glycolysis- and gluconeogenesis-related genes, along with their enzyme activities (p < 0.05). Supplementation with BBR increased (p < 0.05) intestinal protease activity in B5, B10 and B20, lipase activity in B10 and B20 and amylase activity in B20. BBR reduced the liver voiding rate and fat content. These results indicated that dietary supplementation with BBR at 1 and 2 g/kg was beneficial for promoting growth and health in largemouth bass. The improved glycolysis and inhibited gluconeogenesis may account for the reduced hyperglycaemia by BBR. In addition, enhancing the activity of intestinal digestive enzymes is an effective way for BBR to improve carbohydrate utilization in largemouth bass.

Macronutrient Signals for Adaptive Modulation of Intestinal Digestive Enzymes in Two Omnivorous Galliforms

Most birds studied to date (15 out of 16 species) have shown the ability to adaptively modulate at least one small intestinal digestive enzyme activity to match the composition of macronutrient levels in their diet. Limited work on Galloanserae (waterfowl, quails, and chickens) suggested that this clade may have the mechanisms to modulate intestinal disaccharidase but not peptidase activity (6 out of 7 species). We tested this hypothesis in immature (70‐72 d) northern bobwhites (Colinus virginianus) and juvenile (20 d) and adult (230 d) domestic chickens (Gallus gallus domesticus) by raising them on 3 semisynthetic diets varying in starch, protein, and lipid composition for 7‐9 d (bobwhites) or 15 d (chickens). Birds were then euthanized, intestinal tissue harvested, and enzyme activities measured in tissue homogenates from proximal, medial and distal small intestine. We found that (1) disaccharidase (maltase and sucrase) activities were induced by dietary starch in both juvenile and adult chickens but not in northern bobwhites; (2) aminopeptidase‐N activities were induced by dietary protein in both bobwhites and juvenile and adult chickens; and (3) disaccharidase activities were suppressed by dietary lipid in both bobwhites and juvenile and adult chickens. Generally, diet effects were similar all along the intestine or most pronounced in the medial intestine (chicken disaccharidases). In chickens, age did not affect the diet‐driven modulation pattern except in sucrase activity – modulation was found in the distal but not in the proximal intestine in juveniles and the reverse was found in adults. We conclude that there is no general pattern with respect to which nutrient classes of digestive enzymes are adaptively modulated in the small intestine of Galloanserae, and that the modulation of each enzyme in species in this clade likely relates to its respective digestive ecology. On the other hand, the suppressive effect of lipid on the intestinal disaccharidases appears to be present in all vertebrates (birds, mammals, and fish) tested to date, although the biological significance of this effect is not yet understood. We will present a summary of adaptive intestinal digestive enzyme modulation patterns of all birds thus far studied, arranged in a cladogram.

Effects of dietary carbohydrate levels on growth performance, body composition, glucose/lipid metabolism and insulin signaling pathway in abalone Haliotis discus hannai

The present study investigated the effects of different dietary carbohydrate levels on the growth performance, body composition, glucose/lipid metabolism and insulin signaling pathway in abalone Haliotis discus hannai. Eight experimental diets with graded levels of carbohydrates (18.08%, 22.10%, 26.10%, 29.90%, 34.00%, 38.01%, 41.98% and 45.55%, named as T1, T2, T3, T4, T5, T6, T7 and T8, respectively) were designed to feed abalone (initial weight 22.52 ± 0.05 g) for 110 days. The results showed that the diet containing 38.01% carbohydrate significantly increased the survival rate (SR) and weight gain rate (WGR) of abalone (P < 0.05). Based on the quadratic regression mode of WGR, the optimal dietary carbohydrate level for abalone was estimated to be 37.05%. The activities of intestinal digestive enzymes were significantly increased in the T6 group. Moreover, the expressions of pyruvate kinase (pk) and glucose-6-phosphate dehydrogenase (g6pdh) in digestive glands were up-regulated with the increase of carbohydrate content in diets, while the expression of hexokinase (hk) reached the maximum in the T6 group. The highest expressions of phosphoenolpyruvate carboxykinase (pepck), glucose-6-phosphatase (g6pase) and insulin signaling pathway related genes were found in the T6 group. The expressions of key genes related to lipolysis reached the highest in the T6 group, and then down-regulated with the further increasing dietary carbohydrate levels. The expression of key genes of lipogenesis was up-regulated with the increasing dietary carbohydrate levels. In conclusion, 38.01% of dietary carbohydrate level improved the growth performance of abalone. Dietary carbohydrate levels influenced the glucose and lipid metabolism including insulin signaling pathway. Abalone potentially had the capability to deal with a high-carbohydrate load (45.55%) by increasing glycolysis and decreasing gluconeogenesis. Meanwhile, it promoted lipid synthesis and inhibited lipolysis under high dietary carbohydrate load.

Effect of dietary oxidized fish oil on growth performance, physiological homeostasis and intestinal microbiome in hybrid grouper (♀ Epi-nephelus fuscoguttatus × ♂ Epinephelus lanceolatus)

Oxidized fish oil, as a harmful ingredient in feed, has a negative impact on aquatic animals. But the effect of oxidized fish oil on hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus), especially the intestinal flora, is not yet understood. In the current study, a 65-day raising experiment with diets containing 0 g/kg, 30 g/kg, 60 g/kg, and 90 g/kg oxidized fish oil was performed (called as R, L, M and H group respectively) to investigate the effects of oxidized fish oil on growth performance, whole body composition, serum biochemical index, intestinal digestive enzyme activities and microbiome composition in juvenile hybrid grouper. Oxidized fish oil inhibited growth performance of pearl gentian grouper. The Moisture, crude protein, and ash content in whole body increased as increasing dietary oxidized fish oil content. The vitamin E content and antioxidant enzyme activity in serum including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were significantly increased as the oxidized fish oil in the diet increased, but malondialdehyde (MDA) content in serum was significantly decreased. Meanwhile, the D-Lactate (D-LA) and interleukin-10 (IL-10) content in serum was promoted by oxidized fish oil, but interleukin-6 (IL-6) content was suppressed. Moreover, the intestinal digestive enzyme activities were promoted by oxidized fish oil. The oxidized fish oil reduced alpha diversity of intestinal bacteria. At the same time, oxidized fish oil changed the structure of grouper intestinal flora according to beta diversity and line discriminant analysis (LDA) effect size. In conclusion, oxidized fish oil inhibited growth performance, changed the composition of the body and caused oxidative stress and inflammation in the body, but it promoted the secretion of digestive enzymes in the intestine. More importantly, oxidized fish oil reduced the diversity of intestinal flora and changed the structure of intestinal flora.

Exploring the Intestinal Microbiota and Metabolome Profiles Associated With Feed Efficiency in Pacific Abalone (Haliotis discus hannai).

Feed efficiency (FE) is critical to the economic and environmental benefits of aquaculture. Both the intestines and intestinal microbiota play a key role in energy acquisition and influence FE. In the current research, intestinal microbiota, metabolome, and key digestive enzyme activities were compared between abalones with high [Residual feed intake (RFI) = −0.029] and low FE (RFI = 0.022). The FE of group A were significantly higher than these of group B. There were significant differences in intestinal microbiota structures between high- and low-FE groups, while higher microbiota diversity was observed in the high-FE group. Differences in FE were also strongly correlated to variations in intestinal digestive enzyme activity that may be caused by Pseudoalteromonas and Cobetia. In addition, Saprospira, Rhodanobacteraceae, Llumatobacteraceae, and Gaiellales may potentially be utilized as biomarkers to distinguish high- from low-FE abalones. Significantly different microorganisms (uncultured beta proteobacterium, BD1_7_clade, and Lautropia) were found to be highly correlated to significantly different metabolites [DL-methionine sulfoxide Arg-Gln, L-pyroglutamic acid, dopamine, tyramine, phosphatidyl cholines (PC) (16:0/16:0), and indoleacetic acid] in the high- and low-FE groups, and intestinal trypsin activity also significantly differed between the two groups. We propose that interactions occur among intestinal microbiota, intestinal metabolites, and enzyme activity, which improve abalone FE by enhancing amino acid metabolism, immune response, and signal transduction pathways. The present study not only elucidates mechanisms of variations in abalone FE, but it also provides important basic knowledge for improving abalone FE by modulating intestinal microbiota.

Textural quality, growth parameters and oxidative responses in Nile tilapia (Oreochromis niloticus) fed faba bean water extract diet.

Texture is one of the key quality attributes used in the fresh and processed fish industry to assess product quality and consumer acceptability. To improve the textural quality of tilapia, we formulated the expanded pellet diet (EPD) and pellet diet (PD), both containing faba bean (Vicia faba, FB) water extract, a previously reported potential aquafeed additive to increase flesh texture. The common diet was used as a control. After Nile tilapia (Oreochromis niloticus) were fed three kinds of experimental diet for 120 days, muscle textural quality, growth parameters, oxidative response and immune parameters were analyzed. The results showed that there was no significant difference in the growth parameters between the three groups (P > 0.05). The highest measure of textural quality (hardness and chewiness) was found for the PD group, followed by the EPD and the control (P < 0.05). Less oxidative damage to the hepatopancreas and intestine was found in the EPD compared with the PD group, as demonstrated by the decreased levels of reactive oxygen species and increased levels of nicotinamide adenine dinucleotide and intestinal digestive enzyme activity (amylase and lipase). Taken together, this study highlights the potential usefulness in commercial settings of FB water extract for improving the textural quality of tilapia, and EPD containing faba bean water extract could be more advanced substitute for faba bean in tilapia culture in term of both effectiveness in textural quality improvement and health status enhancement compared with PD.

Effects of Feeding Frequency and Dietary Protein/Carbohydrate Ratios on Gilthead Seabream (Sparus aurata) Intestinal Functionality and Health

The present study evaluated the effects of feeding frequency (FF) and dietary protein/carbohydrate (P/CH) ratios on intestinal histomorphology, microbiota profile, and digestive and oxidative stress-related enzyme activities of gilthead seabream (Sparus aurata). To this purpose, two practical diets were formulated: one with 50% P and 10% CH (P50/CH10) and other with 40% P and 20% CH (P40/CH20). Triplicate groups of fish with9.1±0.01 gwere fed these diets for 60 days until visual satiation at a FF of 1, 2, or 3 meals per day. Distal intestine histomorphology was not affected by diet composition or FF. However, the pyloric caeca (PC) of fish fed 1 meal per day presented more gut fold height alterations than the other groups, except in fish fed diet P50/CH10 3 meals per day, where no changes was observed. Fish fed diet P40/CH20 3 meals per day also presented higher PC submucosa cellularity than the other groups. Fish fed diet P40/CH20 presented a higher number of operational taxonomic units, microbial richness, and diversity indices than fish fed diet P50/CH10. Amylase was the only measured digestive enzyme affected by the experimental conditions, presenting higher activity in fish fed diet P50/CH10 once per day. Glucose-6-phosphate dehydrogenase activity was lower in fish fed 2 meals per day than only 1. While catalase activity was lower in fish fed 2 than 3 meals per day. Glutathione reductase activity was the only measured parameter affected both by dietary P/CH ratio and FF, being inferior in fish fed once per day the P50/CH10 diet than the P40/CH20 diet and, also in the P50/CH10 diet, to fish fed 1 than those fed 3 meals per day. Overall, no major interactions was observed between dietary P/CH ratio and FF; however, a P40/CH20 diet fed 2 meals per day might be recommended for gilthead seabream juveniles.

Effects of Replacing Fishmeal by Raw or Lactobacillus acidophilus-Fermented Soybean Meal on Growth, Intestinal Digestive and Immune-Related Enzyme Activities, Morphology, and Microbiota in Turbot (Scophthalmus maximus L.)

This study was performed to investigate the fermentation efficiency of Lactobacillus acidophilus and compare the effects of dietary soybean meal (SM) or L. acidophilus-fermented SM (LASM) on turbot. Two hundred and seventy juvenile turbots ( 13.50 ± 0.13 g ) were randomly divided into three treatments fed with a fishmeal-based diet (CNT) and two experimental diets with 45% fishmeal protein replaced by SM or LASM for 8 weeks. The results showed that fermentation significantly improved the essential amino acid profile, increased the lactic acid content, and reduced the antinutritional factor level in SM. Inferior growth of fish was observed in the SM group after the feeding trial, while the LASM group exhibited comparable performance to the CNT group. Activities of intestinal digestive enzymes (trypsin and diastase) and immune-related enzymes (alkaline phosphatase, acid phosphatase, and lysozyme) decreased significantly in the SM group, while no significant reduction was found in the LASM group compared to the CNT group. Dietary LASM alleviated SM-induced intestinal pathological disruption with higher villus and normal lamina propria width. Dietary LASM positively regulated the intestinal microbiota, making the overall profile more coherent with that in the CNT group. Spearman’s correlation analysis revealed that the altered intestinal microbiota was closely linked to the digestive enzyme activities. Collectively, this study indicated that L. acidophilus fermentation significantly improved the nutritional quality of SM and relieved SM-induced adverse effects on turbot, in terms of growth, intestinal digestive and immune-related enzyme activities, morphology, and microbiota.

Condensed tannins alleviate aflatoxin B1-induced injury in Chinese sea bass (Lateolabrax maculatus)

A 56-day feeding trial was conducted to evaluate the protective mechanism of condensed tannins (CT) on the dietary aflatoxin B1 (AFB1)-induced changes in body compositions, intestinal digestive enzyme activities, antioxidant and immune parameters, liver histomorphology, and the AFB1 residue contents in the liver and muscle of Chinese sea bass (Lateolabrax maculatus) (initial body weight 2.9 ± 0.1 g). Three diets were formulated to contain 0 mg/kg of AFB1 and 0 g/kg of CT (T1), 1.0 mg/kg of AFB1 and 0 g/kg of CT (T2), and 1.0 mg/kg of AFB1 and 1.0 g/kg of CT (T3), respectively. Each diet was randomly assigned to three tanks with 40 fish per tank. Fish were fed to apparent satiation twice daily. Results indicated that the survival rate, whole body compositions of dry matter, crude protein and crude lipid contents, and intestinal digestive enzyme activities of amylase, lipase and trypsin were not significantly different among diets (P > 0.05). Fish fed T2 had lower (P < 0.05) albumin, high density lipoprotein cholesterol, superoxide dismutase, catalase and glutathione peroxidase, but higher (P < 0.05) triacylglycerol, aspartate aminotransferase, malondialdehyde, alkline phosphatase, lysozyme and immunoglobulin M than those of fish fed T1 and T3. As compared with T1, hepatocytes in T2 and T3 had obvious and slight vacuolar degeneration, some white spots of necrosis and inflammatory cell infiltration, respectively. T2 had higher (P < 0.05) AFB1 residue contents in the liver and muscle than T1, and the AFB1 residue contents in liver and muscle were not significantly different (P > 0.05) between T1 and T3. In conclusion, inclusion of 1.0 mg/kg AFB1 in L. maculatus diet induced liver injury and lipid dysmetabolism, caused imbalance of liver antioxidant and immune system, and increased AFB1 residue contents in liver and muscle of fish. Supplementation of 1.0 g/kg CT protected against AFB1-induced injury and reduced AFB1 residue contents in L. maculatus.

Effects of dietary supplementation with essential oils and protease on growth performance, antioxidation, inflammation and intestinal function of weaned pigs.

This experiment evaluated the impacts of essential oils (EO) and protease (PRO), independently or in combination, on growth performance, antioxidation, inflammation and intestinal function of weaned pigs. One hundred and sixty weaned pigs (21 d of age, BW of 6.74 ± 0.20 kg) were randomly divided into 4 treatments with 8 replicate pens of 5 pigs per pen. Dietary treatments included the following: 1) control diet (CON), 2) CON with 300 mg/kg essential oils (EO), 3) CON with 500 mg/kg protease (PRO), 4) CON with 300 mg/kg essential oil and 500 mg/kg protease (EO + PRO). On d 8, one pig from each pen was selected for sampling. The remaining pigs were fed for an additional week and growth performance was monitored during this period. Dietary treatments had no marked effects (P > 0.05) on the growth performance of pigs. However, pigs receiving EO diet had higher (P < 0.05) serum glutathione peroxidase (GSH-Px) activity, and tended to decrease (P = 0.063) serum concentration of tumor necrosis factor-α (TNF-α). In addition, pigs receiving EO diet had higher (P < 0.05) abundances of phylum Actinobacteria, and genera Bifidobacterium, and lower (P < 0.05) phylum Bacteroidetes and genera Alloprevotella in colonic digesta. Pigs receiving PRO diet decreased (P < 0.05) the serum concentration of malondialdehyde (MDA) and diamine oxidase activity, increased (P < 0.05) the villus height and the ratio of villus height to crypt depth in duodenum, increased sucrase activity in jejunal mucosa, and also increased the abundance of phylum Actinobacteria in colonic digesta. Furthermore, the synergistic effects of EO and PRO was observed (P < 0.05) for pigs with decreasing serum TNF-α concentration and increasing serum GSH-Px activity. Collectively, the results indicated that dietary supplementation of EO and PRO had no significant effects on growth performance of weaned pigs. EO diet appeared to improve antioxidant activity and intestinal microbiota, while PRO diet improved intestinal morphology and digestive enzyme activity, and there was a synergistic effect of EO and PRO on reducing inflammatory parameters in weaned pigs.

Effects of dietary xylooligosaccharide on growth, digestive enzymes activity, intestinal morphology, and the expression of inflammatory cytokines and tight junctions genes in triploid Oncorhynchus mykiss fed a low fishmeal diet

The purpose of this study was to show how dietary xylooligosaccharides (XOS) affect growth and intestinal digestive enzyme activity, histology, inflammatory cytokines, barrier function gene expression, and microbiota of juvenile rainbow trout (Oncorhynchus mykiss). Different diets (G1, G2, G3, G4, and G5) containing graded levels of XOS (0, 2.5, 5.0, 7.5, and 10.0 g/kg) were fed to triplicate groups of 30 fish (initial average weight 20.85 ± 0.48 g) for 56 days. The fish fed 10 g/kg XOS had significantly improved weight gain (P < 0.05). Intestinal lipase and amylase activity were significantly improved (P < 0.05). Intestinal histology in the height of the villi was also significantly improved (P < 0.05). TNF-alpha factor (TNF-α) and interleukin 6 (IL-6) were significantly lower in G4–G5 than that in G1 (P < 0.05); Interleukin 10 (IL-10), claudin-1, and ZO-1 showed the opposite trend. Dietary XOS altered the intestinal bacterial composition. At the phylum level, dietary XOS supplementation resulted in a decrease in abundance of the Proteobacteria in G2 and G5 treatments. At the genus level, compared to the control group, the genus Lactobacillus showed an increase with dietary XOS supplementation in G3–G5 treatments. Overall, feeding juvenile triploid O. mykiss 5.0–10.0 g/kg XOS improved growth and intestinal health by promoting intestinal development, limiting intestinal damage and inflammation, and regulating the community structure of the intestinal microbiota.

Effects of dietary ESTAQUA® yeast culture supplementation on growth, immunity, intestinal microbiota and disease-resistance against Vibrio harveyi in hybrid grouper (♀Epinephelus fuscoguttatus×♂E. lanceolatus)

This study investigated the effects of dietary supplementation of ESTAQUA® yeast culture (YC) on the growth, immunity, intestinal microbiota, and disease-resistance against Vibrio harveyi in hybrid grouper (♀Epinephelus fuscoguttatus×♂E. lanceolatus) at 0% (C0), 2% (N1), and 4% (N2). After 8 weeks of the feeding trial, the results indicated that the survival rate (SR), weight gain rate (WGR), and specific growth rate (SGR) of hybrid grouper were significantly higher in the N1 (2%) and N2 (4%) group than those in the control group (P < 0.05). Serum superoxide dismutase (SOD), catalase (CAT), total protein (TP), alkaline phosphatase (AKP), acid phosphatase (ACP), and immunoglobulin (IgM) activities were significantly higher in the N2 (4%) group (P < 0.05). Contrary to the control, aspartate aminotransferase (AST), alanine aminotransferase (ALT), malondialdehyde (MDA), and glucose (GLU) were notably decreased in the N2 (4%) group (P < 0.05). The activity of intestinal digestive enzymes was significantly higher in the experimental groups than that in the control group (P < 0.05). Furthermore, at the phylum level, the relative abundance of Actinobacteria and Bacteroidetes was remarkably higher in the N2 (4%) group than that in the control group (P < 0.05). The relative abundance of Blautia and Lactobacillus was notably higher in the N2 (4%) group at the genus level (P < 0.05). Hybrid grouper in the N1 (2%) and N2 (4%) groups effectively improved intestinal villus height and width (P < 0.05). Lastly, the protection against V. harveyi challenge in hybrid grouper was enhanced in the YC treatment group, while N2 (4%) experienced the highest cumulative SR of 80%. In conclusion, the N2 (4%) treatment group is suggested as the best to improve the growth and immunity of hybrid grouper.

Effects of a new fermented soya bean meal on growth performance, serum biochemistry profile, intestinal immune status and digestive enzyme activities in piglets.

Fermented soya bean meal (FSBM) is believed to have improved nutritional qualities compared with soya bean meal (SBM) and is also cheaper than soya protein concentration (SPC) and fish meal (FM). Therefore, the present study was conducted to compare the effects of FSBM replacing SBM, SPC and FM in diets on growth performance, serum biochemistry profile, short-chain fatty acid concentrations in digesta, intestinal mucosal enzyme activities, intestinal proinflammatory cytokine concentrations and morphology in weaned piglets. One hundred and twenty 28-day-old piglets (Duroc×Landrace×Yorkshire, body weight: 6.73±1.14kg) were randomly allocated to four treatment diets (six replicate pens with five piglets per pen) containing SBM, SPC, FM or FSBM as the protein source, respectively. Dietary FSBM supplementation improved average daily gain (p<0.05), gain to feed ratio (p<0.05), and digestibility of dry matter, gross energy, crude protein and organic matter (p<0.05) in pigs compared with those fed SBM during 0-14days and reduced diarrhoea rate (p<0.05) compared with those fed SBM and FM during 0-14days. Moreover, pigs fed FBSM had greater IgA and IgM contents and antioxidase activities than those provided SBM and SPC on day 14. In addition, the butyrate concentration in the cecum of pigs fed FSBM was greater than those fed the other diets (p<0.05), and the trypsin activity in duodenum and jejunum of pigs provided FSBM was greater than those fed SBM (p<0.05). Moreover, higher villus height (p<0.05) and villus height to crypt depth ratio (p<0.05) and lower crypt depth (p<0.05) in the duodenum of pigs fed FSBM were observed, and pigs fed FSBM had a lower (p<0.05) TNF-α concentration in jejunum compared with those fed SBM. In conclusion, dietary FSBM supplementation to replace SBM, SPC and FM could improve piglets' growth performance, intestinal health and immune function.

Effect of zinc supplementation on growth performance, intestinal development, and intestinal barrier function in Pekin ducks with lipopolysaccharide challenge

This study was conducted to investigate the influence of zinc (Zn) supplementation on growth performance, intestinal development and intestinal barrier function in Pekin ducks. A total of 480, one-day-old male Pekin ducks were divided into 6 groups with 8 replicates: 0 mg/kg Zn, 0 mg/kg Zn +0.5 mg/kg lipopolysaccharide (LPS), 30 mg/kg Zn, 30 mg/kg Zn +0.5 mg/kg LPS, 120 mg/kg Zn, 120 mg/kg Zn +0.5 mg/kg LPS. The duck primary intestinal epithelial cells (DIECs) were divided into 6 groups: D-Zn (Zinc deficiency, treated with 2 µmol/L zinc Chelator TPEN), A-Zn (Adequate Zinc, basal medium), H-Zn (High level of Zn, supplemented with 20 µmol/L Zn), D-Zn + 20 µg/mL LPS, A-Zn + 20 µg/mL LPS, H-Zn + 20 µg/mL LPS. The results were as follows: in vivo, with Zn supplementation of 120 mg/kg reduced LPS-induced decrease of growth performance and intestine damage (P < 0.05), and increased intestinal digestive enzyme activity of Pekin ducks (P < 0.05). In addition, Zn supplementation also attenuated LPS-induced intestinal epithelium permeability (P < 0.05), inhibited LPS-induced the expression of proinflammatory cytokines and apoptosis-related genes (P < 0.05), as well as reduced LPS-induced the intestinal stem cells mobilization of Pekin ducks (P < 0.05). In vitro, 20 µmol/L Zn inhibited LPS-induced expression of inflammatory factors and apoptosis-related genes (P < 0.05), promoted the expression of cytoprotection-related genes, and attenuated LPS-induced intestinal epithelium permeability in DIECs (P < 0.05). Mechanistically, 20 µmol/L Zn enhanced tight junction protein markers including CLDN-1, OCLD, and ZO-1 both at protein and mRNA levels (P < 0.05), and also increased the level of phosphorylation of TOR protein (P < 0.05) and activated the TOR signaling pathway. In conclusion, Zn improves growth performance, digestive enzyme activity, and intestinal barrier function of Pekin ducks. Importantly, Zn also reverses LPS-induced intestinal barrier damage via enhancing the expression of tight junction proteins and activating the TOR signaling pathway.

Starch supplementation improves the reproductive performance of sows in different glucose tolerance status.

This study was to evaluate the effects of glucose tolerance status, maternal starch supplementation and soybean substitution in diets on the performance of dams and their offspring. Eighty-eight pregnant sows (Landrace × Large White) were selected from an initial total of 120 sows, based on blood glucose test values, and assigned to 4 experimental treatments in a 2 × 2 factorial design. The factors were glucose tolerance status (glucose intolerant [GIT] vs. normal glucose tolerant [NGT]) or dietary treatments (corn starch diet [CS] vs. soybean substitution diet [SS]). A higher area under the curve (AUC) for post-meal glucose was observed (P < 0.05) in the GIT group than in the NGT group on d 109 of gestation. The CS group had a lower value of homeostasis model assessment-insulin resistance than the SS group (P < 0.05) on d 109 of gestation. Corn starch supplementation for sows decreased the stillbirth rate (P < 0.05), regardless of the sows' glucose tolerance status. The villus height of the jejunum and the villus height to crypt depth ratio of the ileum were greater in normal birth weight piglets from the CS group than from the SS group (P < 0.01), and so was the activity of sucrase in the jejunum and ileum (P < 0.01). Compared with the SS group, the CS group showed a reduction in pre-weaning mortality rate, an increase in the number of high-birth-weight piglets, and a decrease in the number of low-birth-weight piglets (P < 0.05) under GIT status. In conclusion, sows fed CS decreased stillbirth rate and improved insulin resistance, as well as improving the intestinal morphology and digestive enzyme activities of their progeny, regardless of glucose tolerance status. Additionally, the CS group improved birth weight distribution and decreased pre-weaning mortality rate of piglets under GIT status.