Intestinal Digestive Enzyme Activities Research Articles

Effects of dietary fermented attachments of suspension cage as a replacement for sea mud on growth and intestinal health of sea cucumber Apostichopus japonicus

In the suspension cage culture process, regular cleaning to remove epiphytic organisms from the cage is essential to prevent economic losses due to the sinking of the cage. However, after cleaning, many of attachments from the suspension cage accumulate in the tidal flats, causing environmental pollution and resource wastage. Moreover, because sea cucumbers (Apostichopus japonicus) are sedimentary food organisms, sea mud is typically added to their feed to varying degrees. However, long-term excavation of sea mud can destroy the marine environment. Therefore, developing an alternative new raw feed material to replace sea mud in sea cucumber feed is necessary to promote sustainable development of the A. japonicus aquaculture industry. The aim of this study was to explore the feasibility of using fermented attachments of suspension cage (FASC) as a raw feed material for A. japonicus. Different FASC concentrations (0, 25, 50, 75, and 100 %) were used in A. japonicus feed for 60 d. Replacing Sea mud with 100 % FASC significantly improved sea cucumber growth, reduced the feed coefficient, significantly increased the activity of intestinal digestive enzymes, improved intestinal structure, and enriched intestinal microbiome diversity. Furthermore, expressions of growth genes mapk-7 and fgfr-1 significantly increased in the 100 % FASC treatment compared with that in the control, and that of negative growth regulator gene gdf-8 was inhibited. The results suggested the potential of FASC as a new raw feed material for A. japonicus.

Effects of Salinity on Growth, Digestive Enzyme Activity, and Antioxidant Capacity of Spotbanded Scat (Selenotoca multifasciata) Juveniles

As a euryhaline fish species that inhabits estuarine and coastal regions, the spotbanded scat (Selenotoca multifasciata) experiences growth influences during its larval stage due to variations in salinity. Here, we evaluated salinity required by early-stage spotbanded scat juveniles to achieve the highest growth performance, digestive enzyme activity, survival, and antioxidant capacity. We reared spotbanded scat juveniles (all 0.50 ± 0.05 g) in 0–35‰ salinity gradients for 50 days and recorded their survival rate every 10 days. After 50 experimental days, we measured morphological data, stomach and intestinal digestive enzyme activities, and liver antioxidant enzyme activities and malondialdehyde contents. In general, 5–15‰ salinity led to 100% survival. The 5‰ salinity group demonstrated the highest values for the following measures: final wet body weight; weight gain rate; specific growth rate; growth percentage; average daily gain; stomach amylase and lipase specific activities; and intestinal amylase, lipase, trypsin, and pepsin specific activities. However, stomach trypsin and pepsin activities did not demonstrate significant between-group differences (all p > 0.05). The 25‰ salinity group demonstrated the highest liver superoxide dismutase and glutathione peroxidase activities and malondialdehyde content. Finally, the 0‰ salinity group demonstrated the highest liver catalase activity. Thus, spotbanded scat juveniles demonstrate the highest survival rates, growth performance, and digestive enzyme activity at 5‰ salinity and the strongest oxidative stress responses at 25‰ salinity.

Supplementation of Clostridium butyricum LV1 lyophilised powder to cottonseed protein concentrate basal diets improves growth, intestinal microbiota, and immunity of Litopenaeus vannamei

Clostridium butyricum (CB) is a strictly anaerobic gram-positive probiotic. In this study, CB strain (LV1) was extracted from the intestine of Litopenaeus vannamei for preparing CB lyophilised powder (CBLP, 5.6 × 108 CFU/g) by freeze-drying method, with the aim to explore the effect of CB LV1 lyophilised powder on the growth, intestinal microbiota, and immunity of Litopenaeus vannamei after substitution of fishmeal with cottonseed protein concentrate (CPC). Six isonitrogenous and isolipid diets were formulated with 25% fishmeal in the positive control (FM) and 40% fishmeal replaced by CPC in the negative control (CBLP 0). CBLP was added to the CBLP 0 group at 3 × 105 CFU/g (CBLP 1), 1.2 × 106 CFU/g (CBLP 2), 4.8 × 106 CFU/g (CBLP 3), and 1.92 × 107 CFU/g (CBLP 4), respectively. The results showed that the CBLP 3 group had the highest weight gain rate and specific growth rate (P > 0.05). Serum superoxide dismutase and acid phosphatase activities were remarkably enhanced in the CBLP 2, CBLP 3, and CBLP 4 groups (P < 0.05). CBLP supplementation improved the intestinal digestive enzyme activity. The addition of CBLP optimized the structure of the intestinal microbiota, increased the beneficial bacteria, and reduced the potentially pathogenic bacteria. Chao1, ACE, and Sob indices were elevated in the CBLP 2, CBLP 3, and CBLP 4 groups (P < 0.001). Relish, PO, eIF4E1α, and IGF1 gene expressions were remarkably elevated in the CBLP 3 group (P < 0.01). CBLP further improved the intestinal morphological structure and enhanced the disease resistance. Muscle phenylalanine, histidine, and tyrosine contents were remarkably elevated in the CBLP 1 and CBLP 2 groups (P < 0.05). In conclusion, supplementation of CBLP in CPC basal diets improved the growth, intestinal microbiota, and immunity of Litopenaeus vannamei. Binary regression analysis of SGR indicated that the appropriate addition level of CBLP was 8.79 × 106 CFU/g.

Arecoline inhibits the growth of Spodoptera litura by inducing intestinal metabolic dysfunction

Arecoline (ACL), an active constituent derived from Areca catechu L., exerts various pharmacological effects and serves as a potential plant-based insecticide. However, the effects of ACL on Spodoptera litura, an important and widely distributed agricultural pest, remain unknown. This study aimed to elucidate the mechanism underlying ACL-induced toxicity and its inhibitory effects on larval growth and development through intestinal pathology observations, intestinal transcriptome sequencing, intestinal digestive enzyme activity analysis. The results indicated that ACL exposure leads to pathological alterations in the S. litura midgut. Furthermore, the detection of digestive enzyme activity revealed that ACL inhibits the activities of acetyl CoA carboxylase, lipase, α-amylase, and trypsin. Simultaneously, upregulation of superoxide dismutase activity and downregulation of malondialdehyde levels were observed after ACL exposure. Transcriptome analysis identified 1118 genes that were significantly differentially expressed in the midgut after ACL exposure, potentially related to ACL toxic effects. Notably, ACL treatment downregulated key enzymes involved in lipid metabolism, such as fatty acid binding protein 2-like, pancreatic triacylglycerol lipase-like, pancreatic lipid-related protein 2-like, and fatty acid binding protein 1-like. Taken together, these results suggest that ACL induces midgut damage and impedes larval growth by suppressing digestive enzyme activity in the intestine. These findings can aid in the development of environmentally friendly plant-derived insecticides, utilizing ACL to effectively combat S. litura proliferation.

Early anatomical development of the digestive system and high intestinal digestive enzyme activity in two silverside species, Odontesthes bonariensis and O. hatcheri (Atherinomorpha: Atherinopsidae) Elva

Integrative studies are important for a better understanding of the functional development of fish digestive systems and the consequent design of suitable feeding regimes and ad-hoc diets. To characterize the ontogeny of digestive function in larvae and juveniles of two atherinopsids from South America, Odontesthes bonariensis and O. hatcheri, morphologic, histologic, and intestinal enzyme biochemical analyses were performed. Both species showed a functional digestive system from one week after hatching (wah) with a sustained high-level activity of the cytosolic enzyme leucine alanine peptidase (leu-ala) until 9 and 13 wah in O. hatcheri and O. bonariensis, respectively. Maximum specific leu-ala activities in both species were higher compared to other agastric and most gastric fish. These results and the abundant pinocytic vacuoles in the posterior intestine suggest that cytosolic digestion is crucial for these species. It seems that their apparent anatomically simple digestive system is compensated by an uncommonly early development and function of the digestive tract and accessory organs accompanied by high intestinal cytosolic activity. The above findings contribute to the understanding of the Atherinopsidae digestive model and, for the first time, suggest that under farming conditions, these species could be weaned at an early developmental stage with an appropriate balanced diet.

Potassium diformate affects the growth and development of broilers by improving intestinal function and digestive enzyme activity

Gut health of broiler chickens is essential for production performance. The present study aimed to evaluate the impact of dietary supplementation with potassium diformate (KDF) on growth performance and intestinal health in broiler chickens. A total of 180 Arbor Acres (AA) broiler chickens were randomly allocated into 3 treatments, with 6 replicates, containing 10 chicks in each replicate. The treatment groups were: control group (CON) was fed a basal diet; KDF-4 groups fed the basal diet with 4 g/kg KDF; KDF-8 groups fed the basal diet with 8 g/kg KDF. The experiment period lasted for 42 d. During the starter phase, the ADFI and F/G of broilers in KDF groups were lower (P < 0.05) compared to the CON group. Furthermore, the BW and ADG in KDF-4 group was improved (P<0.05). The treatment groups exhibited a significant increase (P < 0.05) in both ADG and ADFI during the grower and overall phase. Moreover, the F/G in KDF-4 group was lower (P < 0.05) compared to the CON and KDF-8 groups. The semi-eviscerated weight rate (SEWR), eviscerated carcass weight rate (ECWR), pectoral muscle rate (PMR), and leg muscle rate (LMR) of broilers were improved (P < 0.05) in KDF groups. The serum levels of glucose (GLU) and UREA (UA) were significantly higher (P < 0.05) in KDF-8 group. Additionally, the nutrient apparent utilization rate of dry matter (DM), energy (EE), and crude protein (CP) were improved (P < 0.05) in KDF-4 group. The villus height (VH) and villus height to crypt depth ratio (V/C) of duodenum, jejunum, and ileum were higher (P < 0.05) in KDF groups compared to the CON group, while crypt depth (CD) was significantly reduced (P < 0.05). The digestive enzyme activities of lipase (LIP), amylase (AMS), or trypsin (TPS) were significantly enhanced (P < 0.05) in the intestinal chyme, while the total bacterial count, Escherichia coli, Lactobacilli, Bifidobacteria, and Bacillus were reduced (P < 0.05) in the ileum. This study demonstrates that the inclusion of KDF in the diet of broilers leads to improvements in growth, slaughter performance, nutrient utilization rate, and maintenance of intestinal health.

Responses of Digestive, Antioxidant, Immunological and Metabolic Enzymes in the Intestines and Liver of Largemouth Bass (Micropterus salmoides) under the Biofloc Model.

To investigate the activities of intestinal digestive enzymes, liver antioxidant enzymes, immunological enzymes, and glucometabolic enzymes in largemouth bass (Micropterus salmoides) under the biofloc model, an experiment was conducted in 300-liter glass tanks. The experiment comprised a control group, which was fed a basal diet, and a biofloc group, where glucose was added to maintain a C/N ratio of 15. Each group had three parallel setups, with a stocking density of 20 fish per tank. The experiment ran for 60 days, employing a zero-water exchange aquaculture model. The results showed that at the end of the culture period, there were no significant differences between the initial weight, final weight, WGR, SGR, and SR of the biofloc group and the control group of largemouth bass (p > 0.05), whereas the lower FCR and the higher PER in the biofloc group were significant (p < 0.05); intestinal α-amylase, trypsin, and lipase activities of largemouth bass in the biofloc group were significantly increased by 37.20%, 64.11%, and 51.69%, respectively, compared with the control group (p < 0.05); liver superoxide dismutase and catalase activities, and total antioxidant capacity of largemouth bass in the biofloc group were significantly increased by 49.26%, 46.87%, and 98.94% (p < 0.05), while the malondialdehyde content was significantly reduced by 19.91% (p < 0.05); liver lysozyme, alkaline phosphatase, and acid phosphatase activities of largemouth bass in the biofloc group were significantly increased by 62.66%, 41.22%, and 29.66%, respectively (p < 0.05); liver glucokinase, pyruvate kinase, glucose-6-phosphate kinase, pyruvate kinase, glucose-6-phosphatase, and glycogen synthase activities were significantly increased by 46.29%, 99.33%, 32.54%, and 26.89%, respectively (p < 0.05). The study showed that the biofloc model of culturing largemouth bass can not only enhance digestive enzyme activities, antioxidant capacity, and immune response but can also promote the process of glucose metabolism and reduce feeding costs. This study provides data support for healthy culturing of largemouth bass in future production, provides a theoretical reference for optimizing the biofloc technology culture model, and is crucial for promoting the healthy and green development of aquaculture.

Unlocking the therapeutic potential of Huoxiang Zhengqi San in cold and high humidity-induced diarrhea: Insights into intestinal microbiota modulation and digestive enzyme activity

Huoxiang Zhengqi San (HXZQS), a traditional Chinese herbal formula, enjoys widespread use in Chinese medicine to treat diarrhea with cold-dampness trapped spleen syndrome (CDSS), which is induced by exposure to cold and high humidity stress. This study aimed to explore its therapeutic mechanisms in mice, particularly focusing on the intestinal microbiota. Forty male SPF-grade KM mice were allocated into two groups: the normal control group (H-Cc, n = 10) and the CDSS group (H-Mc, n = 30). After modeling, H-Mc was subdivided into H-Mc (n = 15) and HXZQS treatment (H–Tc, n = 15) groups. Intestinal samples were analyzed for enzyme activity and microbiota composition. Our findings demonstrated a notable reduction in intestinal lactase activity post-HXZQS treatment (P < 0.05). Lactobacillus johnsonii, Lactobacillus reuteri, and Lactobacillus murinus emerged as the main dominant species across most groups. However, in the H-Mc group, Clostridium sensu stricto 1 was identified as the exclusive dominant bacteria. LEfSe analysis highlighted Clostridiales vadinBB60 group and Corynebacterium as differential bacteria in the H–Tc group, and Cyanobacteria unidentified specie in the H-Mc group. Predicted microbiota functions aligned with changes in abundance, notably in cofactors and vitamins metabolism. The collinear results of the intestinal microbiota interaction network showed that HXZQS restored cooperative interactions among rare bacteria by mitigating their mutual promotion. The HXZQS decoction effectively alleviates diarrhea with CDSS by regulating intestinal microbiota, digestive enzyme activity, and microbiota interaction. Notably, it enhances Clostridium vadinBB60 and suppresses Cyanobacteria unidentified specie, warranting further study.

Effects of Plant Polysaccharides Combined with Boric Acid on Digestive Function, Immune Function, Harmful Gas and Heavy Metal Contents in Faeces of Fatteners.

The experiment aimed to investigate the effects of plant polysaccharides combined with boric acid on digestive function, immune function and harmful gas and heavy metal contents in the faeces of fatteners. For this study, 90 healthy crossbred fatteners were selected and randomly divided into five groups: the control group was fed with a basal diet (Con); experimental group I was fed with basal diet + 40 mg/kg boric acid (BA); experimental group II was fed with basal diet + 40 mg/kg boric acid + 400 mg/kg Astragalus polysaccharides (BA+APS); experimental group III was fed with basal diet + 40 mg/kg boric acid + 200 mg/kg Ganoderma lucidum polysaccharides (BA+GLP); and experimental group IV was fed with basal diet + 40 mg/kg boric acid + 500 mg/kg Echinacea polysaccharides (BA+EPS). Compared with Con, the average daily gain (ADG), the trypsin activities in the duodenum and jejunum, the IL-2 levels in the spleen, the T-AOC activities and GSH-Px contents in the lymph node of fattening were increased in the BA group (p < 0.05), but malondialdehyde content in the lymph and spleen, and the contents of NH3, H2S, Hg, Cu, Fe and Zn in the feces and urine were decreased (p < 0.05). Compared with the BA, the ADG, gain-to-feed ratio (G/F), the trypsin and maltase activities in the duodenum and jejunum were increased in the BA+APS (p < 0.05), and the T-SOD activities in the spleen and T-AOC activities in the lymph node were also increased (p < 0.05), but the H2S level was decreased in the feces and urine (p < 0.05). Compared with the BA, the ADG, G/F and the trypsin and maltase activities in the duodenum were increased in the BA+GLP and BA+EPS (p < 0.05), the activities of maltase and lipase in the duodenum of fatteners in the BA+GLP and the activities of trypsin, maltase and lipase in the BA+EPS were increased (p < 0.05). Gathering everything together, our findings reveal that the combined addition of boric acid and plant polysaccharides in the diet of fatteners synergistically improved their growth performance and immune status. That may be achieved by regulating the activity of intestinal digestive enzymes, improving the antioxidant function and then promoting the digestion and absorption of nutrients. Furthermore, the above results reduce the emission of harmful gases and heavy metals in feces and urine.

Pediococcus pentosaceus ZZ61 enhances growth performance and pathogenic resistance of silkworm Bombyx mori by regulating gut microbiota and metabolites

Probiotics have attracted considerable attention in animal husbandry due to their positive effect on animal growth and health. This study aimed to screen candidate probiotic strain promoting the growth and health of silkworm and reveal the potential mechanisms. A novel probiotic Pediococcus pentosaceus strain (ZZ61) substantially promoted body weight gain, feed efficiency, and silk yield. These effects were likely mediated by changes in the intestinal digestive enzyme activity and nutrient provisioning (e.g., B vitamins) of the host, improving nutrient digestion and assimilation. Additionally, P. pentosaceus produced antimicrobial compounds and increased the antioxidant capacity to protect the host against pathogenic infection. Furthermore, P. pentosaceus affected the gut microbiome and altered the levels of gut metabolites (e.g., glycine and glycerophospholipids), which in turn promotes host nutrition and health. This study contributes to an improved understanding of the interactions between probiotic and host and promotes probiotic utilization in sericulture.

Effects of Bacillus cereusYB1 on growth, intestinal digestive enzyme activity, liver antioxidant enzyme activity, and intestinal structure of black rockfish, Sebastes schlegelii

AbstractWe aimed to investigate the effects of Bacillus cereus YB1 on the growth, intestinal digestive enzyme activity, liver antioxidant enzyme activity, and intestinal tissue structure of juvenile black rockfish (Sebastes schlegelii). A 50‐day feeding experiment was conducted. Feeding was conducted in four diet groups: control group with no YB1 supplement in diet and three treatment groups E‐L, E‐M, and E‐H containing 105, 106, and 107 CFU/g YB1, respectively. The results revealed that the weight gain and specific growth rate of juvenile fish significantly increased, while the feed coefficient was reduced in all three diet treatment groups. This indicated that the growth of black rockfish was significantly and positively affected by YB1 feeding. Enzyme activity in the intestinal tract was not significantly affected by YB1. However, the activity of protease, amylase, and lipase increased because of YB1 treatment, except for the proteases in the E‐M diet group. Meanwhile, no significant differences were recorded in the activities of the antioxidant enzymes in liver, but the level of catalase, superoxide dismutase, and malondialdehyde activities in treatments shows a better performance compared with the control in overall perspective. Furthermore, the structural features of the intestine (i.e., number of intestinal villi, length of gut villi, and thickness of muscularis) was significantly elevated with the inclusion of B. cereus YB1 in the diet. These results reveal that dietary supplementation of B. cereus YB1 is beneficial to the boosting of enzymatic activities and structure of intestinal tissue as well as the antioxidative ability of liver tissue. Such findings suggest that fish growth would be improved under YB1 feeding conditions.

Preparation of valine-curcumin conjugate and its in vitro antibacterial and antitumor activity and in vivo biological effects on American eels (Anguilla rostrata)

Curcumin (Cur) exhibits diverse natural pharmacological activities, despite its limited water solubility (hydrophobicity) and low bioavailability. In this investigation, a valine-curcumin conjugate (Val-Cur) was synthesized through amino acid side chain modification, and its solubility increased to 1.78 mg/mL. In vitro experimental findings demonstrated that the antibacterial activity of Val-Cur against Escherichia coli, Staphylococcus aureus, Aeromonas hydrophila, and Vibrio parahaemolyticus was significantly superior to that of Cur. The inhibition rate of Val-Cur against HepG2 (human hepatocellular carcinoma) cells was higher than that of Cur at low concentrations (below 25 μmol/L), although the IC50 value of Val-Cur did not differ significantly from that of Cur. In vivo biological effects of Val-Cur were assessed by adding it into the feed (150 mg/kg) of American eels (Anguilla rostrata). Val-Cur significantly improved the growth performance (↑weight gain rate, ↑specific growth rate, and ↓feed conversion rate) and activities of intestinal digestive enzymes (amylase and lipase) and antioxidant enzymes (superoxide dismutase) in American eels. Additionally, Val-Cur significantly improved serum biochemical indices (↑high-density lipoprotein cholesterol, ↓low-density lipoprotein cholesterol, ↓aspartate and alanine aminotransferases). Furthermore, Val-Cur increased intestinal microbial diversity, reduced the abundance of potentially pathogenic bacteria (Spiroplasma, Clostridium, and Pseudomonas), and elevated the abundance of beneficial digestion-promoting bacteria (Romboutsia, Phyllobacterium, Romboutsia sedimentorum, and Clostridium butyricum) conducive to glucose metabolism (P < 0.05). To the best of our knowledge, this study is the first to explore water-soluble curcumin in aquaculture, and the findings will lay the groundwork for the potential application of water-soluble curcumin in the field of aquaculture.

Effects of dietary pectin on the growth performance, intestinal barrier, and antioxidant status of juvenile rainbow trout (Oncorhynchus mykiss)

To evaluate the effects of dietary pectin on growth performance, intestinal barrier, and antioxidant status of juvenile rainbow trout (Oncorhynchus mykiss), 10-week feeding trial was conducted. Five isoproteic and isoenergetic diets were formulated to contain 0% (P0), 4% (P4), 8% (P8), and 16% (P16) pectin as well as 0.02% pectinase (PE) at the expense of wheat starch, respectively. Dietary inclusion of 416% pectin linearly promoted the feed intake and growth performance but depressed the feed efficiency, but significant differences were only observed between the P16 and P0 groups. Similarly, dietary inclusion of 816% pectin significantly increased the foregut trypsin and amylase activities but decreased the foregut and midgut sucrase activity. The midgut muc2 gene expression level was significantly down-regulated by the inclusion of 16% pectin. Dietary inclusion of 2% pectin increased the abundance of Proteobacteria and Stenotrophomonas but reduced the abundance of Actinobacteria, Bacteroides and Helicobacter; while the lowest values of observed species, Chao1 and ACE indices of intestinal flora were found in the P8 group. Fish fed with the P8 diet exhibited the lowest plasma catalase and midgut glutathione S-transferase activities as well as malondialdehyde content, but the highest midgut malondialdehyde content. Dietary inclusion of 816% pectin significantly depressed the plasma growth hormone (GH), insulin-like growth factor-1 (IGF-1) and mechanistic target of rapamycin contents as well as alanine aminotransferase activity, the hepatic adenosine monophosphate deaminase and glutamate dehydrogenase (GDH) activities. Dietary treatment with 0.02% pectinase did not affect the growth performance, but depressed the foregut sucrase activity, the midgut amylase and sucrase activities, increased the plasma GH and IGF-1 contents as well as hepatic GDH and aspartate aminotransferase activities. In conclusion, high-dose of dietary pectin (816%) may promote the feed intake and intestinal digestive enzyme activities and thereby improve the growth performance of rainbow trout.

Effects of partial replacement of fishmeal with Spirulina platensis powder and addition of Spirulina platensis polysaccharide on growth, nutrition, antioxidant capacity and gut microbiota of Micropterus salmoides

Fish is currently considered a primary protein in the human diet, and the high demand for fish will stimulate the growth of aquaculture. However, a lack of high-quality fish feed (fishmeal) has led to a decline in the quality and yield of aquatic products. Therefore, an alternative high-quality protein source for fish meal is required to sustain the industry. This study assessed the effects of incorporating Spirulina platensis (SP) dried powder as a partial replacement for fishmeal and supplementing with S. platensis purified polysaccharides (PSP) on the growth, nutritional value, and health status of the largemouth bass, Micropterus salmoides, to address the challenges of fishmeal scarcity and promote sustainable development in fish aquaculture. Juveniles were fed four isonitrogenous and isolipidic diets containing SP at 0% (SP0), 3% (SP3) and 6% (SP6) and PSP at 0.3% for 56 days. The results showed that both the SP3 and SP6 groups displayed significantly (P < 0.05) improved growth performance and lower hepatosomatic indices than the control diet (SP0). Whole-body crude protein and protein efficiency significantly increased in both the SP3 and SP6 groups compared with SP0 (P < 0.05). Conversely, crude lipid content notably (P < 0.05) decreased in SP3 (5.96%) and SP6 (5.41%) in contrast to SP0 (6.59%). The muscle amino acid composition of the PSP, SP3, and SP6 groups also improved significantly (P < 0.05) compared to that of the SP0. Liver SOD activity was significantly increased from 1.11 U/mg in SP0 to 1.22–1.24 U/mg in SP3 and SP6 (P < 0.05), while MDA levels declined accordingly. Serum triglyceride levels were significantly lower in SP3 than in SP0 (P < 0.05) but remained stable in the SP6 and PSP groups. Low-density lipoprotein cholesterol decreased significantly in the SP3 and SP6 groups, but no significant effect was observed in the PSP group. Alanine aminotransferase activity was significantly (P < 0.05) lower in the PSP, SP3, and SP6 groups than in SP0. Aspartate aminotransferase activity in PSP and SP3 was significantly lower than in SP0 (P < 0.05), but showed no significant difference with SP6 (P > 0.05). Intestinal trypsin and amylase activities significantly improved in the PSP, SP3, and SP6 groups (P < 0.05), and lipase activities in PSP and SP3 increased significantly compared to those in SP0 (P < 0.05). The intestinal microbiome displayed significantly higher Shannon index scores for SP3 (0.83) and SP6 (0.93) than for SP0 (0.61). The relative abundances of the phylum Fusobacteria and genus Cetobacterium were significantly increased, whereas Proteobacteria and Plesiomonas were significantly decreased in the PSP and SP3 groups compared with that in SP0 (P < 0.05). The present study indicated that the replacement of fishmeal with 3–6% SP and 0.3% PSP addition could improve the growth performance, protein efficiency, muscle nutritional value, liver health, antioxidant capacity, intestinal digestive enzyme activity, and intestinal microbiota diversity of the largemouth bass. Therefore, the partial replacement of SP or the addition of PSP has great potential in promoting healthy aquaculture of largemouth bass.

Expression of chicken epidermal growth factor (cEGF) in Escherichia coli regulates the microflora structure of the duodenum to improve growth performance and intestinal morphogenesis in broilers

ABSTRACT 1. A study used gene synthesis to obtain the functional domains of chicken epidermal growth factor (cEGF) and examined their impact on broiler growth performance, small intestinal morphology, digestive enzyme activities in the intestinal contents and the structure of duodenal microflora. 2. The pET-32a-cEGF recombinant expression vector was constructed. The specific band at 26 KDa was shown by SDS-PAGE analysis and WB results. The purified protein content was shown to be 1687 μg/ml by assay. 3. A total of 180 healthy, one-day-old Arbor Acres male, white-feathered broilers were randomly divided into three dietary treatment groups (six replicate pens, 10 birds per replicate): A control diet (ND); cEGF diet (cEGF), control supplemented with 250 mg/kg cEGF and the control diet (CD) supplemented with 250 mg/kg chlortetracycline. 4. The results showed that feeding the cEGF and CD diet reduced FCR of broilers aged 1–21 d, average daily feed intake (ADFI) at 22–42 d, and the FCR in the whole period (1–42 d; p < 0.05). Compared with the ND group, the cEGF diet increased duodenal α-amylase and alkaline phosphatase activities in the 1–21 d, duodenal lipase, alkaline phosphatase, and ileal alkaline phosphatase activities in the post-period and increased villus height in the duodenum and ileum (p < 0.05). In addition, the ACE and Chao1 index for the birds fed cEGF were higher than the ND group (p < 0.05). At the phyla level, Firmicutes and Proteobacteria were dominant in all groups. At the genus level, the dominant genus was Lactobacillus. The LEfSe analysis showed that the cEGF group was enriched by 11 species including Brevibacillus, Eisenbergiella, Cloacibacterium, Butyricoccus spp. 5. The addition of 250 mg/kg cEGF to the diet can increase growth performance by improving intestinal development and digestive enzyme activity, which may be related to the duodenal intestinal microflora. Therefore, cEGF is an effective alternative to antibiotics in broiler farming.

Effects of dietary arginine supplementation on growth performance, antioxidant capacity, intestinal digestive enzyme activity, muscle transcriptome, and gut health of Siniperca chuatsi

Our study investigated the effects of dietary arginine supplementation on the growth performance, antioxidant capacity, intestinal digestive enzyme activity, muscle transcriptome, and gut health of Chinese perch (Siniperca chuatsi). Four isonitrogenous and isolipidic diets (50% crude protein, 11% crude lipid) with graded levels (2.61%, 2.99%, 3.37%, and 3.82%) of arginine were formulated and processed. A total of 360 Chinese perch (approximately 45–46 g) were randomly divided into four groups with triplicates of 30 fish per cage in each group. Our results revealed that although there was no significant improvement in the growth performance of Chinese perch, their antioxidant capacity and nutritional metabolism were significantly improved. Compared to the control group (without arginine supplementation, 2.61% group), feeding graded arginine levels could significantly (P &amp;lt; 0.05) decrease serum glucose and malondialdehyde (MDA) contents, as well as increase total superoxide dismutase (TSOD) activity. Fish fed a 3.37% arginine diet had the highest TSOD activity in the serum and liver. The intestinal morphological structure was clearer and more uniform in the 2.99% and 3.37% arginine groups. Fish fed with 3.82% arginine had significantly decreased (P &amp;lt; 0.05) muscle valine, glutamate, tyrosine, and total non-essential amino acid contents, with decreased (P &amp;lt; 0.05) intestinal amylase activity. Transcriptome analysis showed that graded arginine levels significantly (P &amp;lt; 0.05) influenced muscle gene expression involved in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of energy metabolism (amino acid, glucose, fatty acid), signaling pathways (mTOR, PI3K-Akt, MAPK, foxO, and insulin pathway), etc. The microbial community structure did not change significantly. Mycoplasma showed the highest abundance in the control group, and Cetobacterium had the highest abundance in the dietary arginine supplementation groups. Network analysis showed that the network complexity of the control group was higher than those of arginine groups. Our finding would help advance the field of arginine nutrition and guide the development of future fish feeds. Based on antioxidant and intestinal health indicators, the optimal dietary arginine requirement for Chinese perch was 2.99%–3.37% of the dry diet (6.08%–6.79% of dietary protein).

Host-associated Bacillus velezensis T20 improved disease resistance and intestinal health of juvenile turbot (Scophthalmus maximus)

The development of host-derived probiotics offers an alternative nutritional strategy for aquaculture. Turbot (Scophthalmus maximus L.) is an important cultured fish in the world. However, research on its host-associated probiotics is limited. The present study evaluates the probiotic potential of Bacillus velezensis T20 (T20) isolated from the intestine of turbot. In the experiment, turbots were fed with two diets: the control diet (CON) and CON supplemented with 1 × 108 CFU/g T20 for 8 weeks. Results showed that the addition of T20 did not affect the growth performance of turbot, but significantly decreased the mortality of turbot challenged by Edwardsiella tarda. Moreover, T20 could survive in the intestine of turbot, it might contribute to the improved intestinal antioxidant capacity, physical barrier and digestive enzymes activities of turbot. In terms of intestinal microbiota, T20 modulated intestinal microbiota communities. Specifically, T20 increased the relative abundances of Bacillus and B. velezensis in both intestinal mucosa and digesta, and decreased potential pathogen such as Mycoplasma, Staphylococcus and Weissella in intestinal digesta. In conclusion, the present study showed that dietary B. velezensis T20 could enhance the disease resistance, improve the communities of intestinal microbiota and promote the intestinal health of turbot.

Rhodiola rosea L. improved intestinal digestive enzyme activities, inflammatory response, barrier and microbiota dysbiosis in Lateolabrax maculatus juveniles fed with high-carbohydrate diets

A 56-d feeding trial was conducted to evaluate the influences of Rhodiola rosea L. on digestive enzyme activities, intestinal barrier, inflammatory response, and microbiota dysbiosis in Lateolabrax maculatus juveniles (9.37 ± 0.03 g) fed with high-carbohydrate diets. Six diets were designed: a control diet (20% corn starch, Control), high-carbohydrate diet (30% corn starch, HC1), and four high-carbohydrate diets supplemented with Rhodiola rosea L. at 30, 60, 90 and 120 mg/kg (HC2, HC3, HC4 and HC5, respectively). Compared with the control group, the HC1 diet remarkably increased α-amylase, lipase, and chymotrypsin activities in the intestine (p < 0.05), as well as the mRNA levels of Claudin-15, NF-κB, TNF-α, IL-1β, and IL-8 (p < 0.05) and the relative abundance of Proteobacteria and Photobacterium in the intestine, which belong to the phylum and genus level, respectively. But the opposite trend was found in muscular thickness and villus lengths (p < 0.05), the mRNA levels of Occludin, ZO-1, and TGF-β (p < 0.05), at the level of phylum and genus level in the HC1 group, and the relative abundance of Firmicutes, Bacteroidetes, and Bacillus in the intestine compared with the control group. Intestinal chymotrypsin activity was significantly higher in the HC3 group and intestinal muscular thickness and villus lengths were also significantly higher in the HC2, HC3, HC4, and HC5 groups compared to the HC1 group (p < 0.05). In addition, Occludin mRNA expression in the intestine was significantly increased in the HC2, HC4, and HC5 groups compared to the HC1 group. ZO-1 and TGF-β mRNA expression in the intestine were significantly increased in the HC2, HC3, HC4, and HC5 groups compared to the HC1 group (p < 0.05). At the phylum level, the relative abundance of Firmicutes and Bacteroidetes was higher in the intestine in the HC2, HC3, HC4, and HC5 groups than that in the HC1 group. On the contrary, intestinal lipase and chymotrypsin activities were significantly decreased in the HC2 group compared to the HC1 group, respectively (p < 0.05). The Claudin-15, NF-κB, TNF-α, IL-1β, and IL-8 mRNA expression in the intestine were significantly decreased in the HC2, HC3, HC4, and HC5 groups compared to the HC1 group (p < 0.05). Besides, at the genus level, compared to the HC1 group, the relative abundance of Photobacterium in the intestine and the diversity of the intestinal microbiota in the HC2, HC3, HC4, and HC5 groups were all decreased. In conclusion, these results demonstrated that the addition of Rhodiola rosea L. in high-carbohydrate diets can improve intestinal digestive enzyme activities, inflammatory response and intestinal barrier-related gene expression, and microbiota dysbiosis in L. maculatus. The suitable supplemental level of Rhodiola rosea L. in high-carbohydrate diets of L. maculatus is 60 mg/kg.

Effects of betaine on growth performance and intestinal health of rabbits fed different digestible energy diets.

An experiment was conducted to determine the effects of betaine on growth performance and intestinal health in rabbits fed diets with different levels of digestible energy. During a 36-d experiment, a total of 144 healthy 35-d-old weaned New Zealand white rabbits with a similar initial body weight (771.05 ± 41.79g) were randomly distributed to a 2 × 3 factorial arrangement. Experimental treatments consisted of two levels of digestible energy (normal: 10.20 and low: 9.60MJ/kg) and three levels of betaine (0, 500, and 1,000mg/kg). Results indicated that rabbits fed the diet with low digestible energy (LDE) had reduced body gain/feed intake on days 1 to 14 and 1 to 36 (P < 0.05), increased the apparent total tract digestibility (ATTD) of neutral detergent fiber, acid detergent fiber (ADF), and n-free extract, and decreased the ATTD of gross energy (GE), crude fiber, and organic matter (OM; P < 0.05). The LDE diet upregulated the gene abundance levels of duodenum junctional adhesion molecule-3 (JAM-3) and downregulated the ileum toll-like receptor 4, myeloid differentiation factor 88, and interleukin-6 (IL-6; P < 0.05). Activities of amylase, lipase, trypsin, and the immunoglobulin M content in the jejunum were decreased in the LDE treatment group (P < 0.05). Dietary betaine supplementation increased the ATTD of GE, dry matter (DM), ADF, and n-free extract by LDE (P < 0.05). The villus height, crypt depth, and goblet cell numbers were decreased, and the villus-crypt ratio was increased in the duodenum (P < 0.05). The gene abundance levels of duodenum IL-2 were downregulated, and the duodenum JAM-2 and JAM-3 were upregulated (P < 0.05). Furthermore, the addition of betaine to the LDE diet increased the ATTD of GE, DM, and OM in rabbits (P < 0.05). Gene abundance levels of ileum IL-6 and duodenum JAM-3 were upregulated (P < 0.05). In summary, LDE diets can reduce the activity of intestinal digestive enzymes and decrease the ATTD of nutrients. However, the addition of betaine to LDE diets improved the intestinal barrier structure and nutrient ATTD in rabbits, with better results when betaine was added at an additive level of 500mg/kg.

Influence of vasoactive intestinal polypeptide on growth performance, nutrient digestibility, nitrogen balance, and digestive enzyme activity in lambs.

This study evaluated if vasoactive intestinal polypeptide (VIP) influences growth performance, nutrient digestibility, nitrogen balance, and digestive enzyme activity. Sixteen wether lambs (69.6 ± 1.9kg) were housed in individual pens, adapted to a corn grain-based diet, and randomly assigned to 2 treatment groups. Lambs were injected intraperitoneally every other day for 28 d with saline (0.9% NaCl) containing no VIP (n = 8; control) or containing VIP (n = 8; 1.3 nmol/kg body weight [BW]). All lambs were transferred to individual metabolic crates for the final 7 d of the experiment to measure nitrogen balance and nutrient digestibility. At the end of the treatment period, lambs were slaughtered, and pancreatic tissue, small intestinal tissue, and rumen fluid were collected for protein, digestive enzymes, ruminal pH, and volatile fatty acid (VFA) analyses. Lambs treated with VIP had greater final BW, average daily gain, and gain:feed (P = 0.01, 0.05, 0.03, respectively). No differences between treatment groups were observed (P ≥ 0.25) for nutrient intake, digestibility, nitrogen retention, ruminal pH, and VFA concentrations. Moreover, VIP treatment did not influence (P ≥ 0.19) plasma glucose, urea N, and insulin concentrations. Treatment with VIP increased (P = 0.03) relative cecum weight (g/kg BW) and decreased (P = 0.05) relative brain weight. Pancreatic and intestinal digestive enzyme activities, except for duodenal maltase (P = 0.02), were not influenced (P ≥ 0.09) by VIP treatment. These data suggest that the administration of VIP may have potential to improve average daily gain and gain:feed in lambs fed grain-based diets.