Intestinal Digestive Enzyme Activities Research Articles

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.

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.

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.

Complete genome analysis of Bacillus velezensis TS5 and its potential as a probiotic strain in mice.

In recent years, a large number of studies have shown that Bacillus velezensis has the potential as an animal feed additive, and its potential probiotic properties have been gradually explored. In this study, Illumina NovaSeq PE150 and Oxford Nanopore ONT sequencing platforms were used to sequence the genome of Bacillus velezensis TS5, a fiber-degrading strain isolated from Tibetan sheep. To further investigate the potential of B. velezensis TS5 as a probiotic strain, in vivo experiments were conducted using 40 five-week-old male specific pathogen-free C57BL/6J mice. The mice were randomly divided into four groups: high fiber diet control group (H group), high fiber diet probiotics group (HT group), low fiber diet control group (L group), and low fiber diet probiotics group (LT group). The H and HT groups were fed high-fiber diet (30%), while the L and LT groups were fed low-fiber diet (5%). The total bacteria amount in the vegetative forms of B. velezensis TS5 per mouse in the HT and LT groups was 1 × 109 CFU per day, mice in the H and L groups were given the same volume of sterile physiological saline daily by gavage, and the experiment period lasted for 8 weeks. The complete genome sequencing results of B. velezensis TS5 showed that it contained 3,929,788 nucleotides with a GC content of 46.50%. The strain encoded 3,873 genes that partially related to stress resistance, adhesion, and antioxidants, as well as the production of secondary metabolites, digestive enzymes, and other beneficial nutrients. The genes of this bacterium were mainly involved in carbohydrate metabolism, amino acid metabolism, vitamin and cofactor metabolism, biological process, and molecular function, as revealed by KEGG and GO databases. The results of mouse tests showed that B. velezensis TS5 could improve intestinal digestive enzyme activity, liver antioxidant capacity, small intestine morphology, and cecum microbiota structure in mice. These findings confirmed the probiotic effects of B. velezensis TS5 isolated from Tibetan sheep feces and provided the theoretical basis for the clinical application and development of new feed additives.

Response of growth performance, antioxidant capacity, and gut microbiota to dietary cholesterol and lecithin in the juvenile Redclaw crayfish, Cherax quadricarinatus

Dietary cholesterol and lecithin are two essential nutrients for the growth and health of crustaceans. A 56-day feeding trial was carried out to evaluate the effects of dietary cholesterol and lecithin on the growth performance, antioxidant capacity, intestinal digestive enzymes, and gut microbiota of the Redclaw crayfish, Cherax quadricarinatus. The crayfish (initial average weight 11.39 ± 0.28 g) were fed with six experimental diets formulated with different contents of cholesterol (0.5% and 1%) and lecithin (1%, 2%, and 3%). No additional cholesterol (0%) and lecithin (0%) were added to the diet of the control group. Crayfish fed the diet with 0.5% cholesterol and 2% lecithin improved growth performance, antioxidant capacity, and intestinal digestive enzyme activities than crayfish fed with other diets. Survival, condition factor, hepatosomatic index, and whole-body proximate composition of crayfish were not significantly affected by different dietary cholesterol and lecithin levels. The Proteobacteria, Firmicutes, and Actinobacteria dominate the gut microbiota community of C. quadricarinatus. In diets with 0.5% cholesterol and 2% lecithin, there were more positive connections and a more complex network structure, which may reduce the risk of pathogen infection. Overall, the combination of 0.5% cholesterol and 2% lecithin in C. quadricarinatus diets was optimal.

Effects of Replacing Fish Meal with Stickwater Hydrolysate and Meal on the Growth, Serum Biochemical Indexes, and Muscle Quality of Yellow Catfish (Tachysurus fulvidraco)

An eight-week feeding experiment was conducted to evaluate the effects of replacing fish meal with stickwater hydrolysate (SWH) or stickwater hydrolysate meal (SWM) on the growth, serum biochemical parameters, intestinal digestive enzyme activity, and muscle quality of yellow catfish (Tachysurus fulvidraco). The control diet (CON) contained 30% fish meal and the remaining five diets were substituted for fish meal with 2.5% (SWM2.5), 5% (SWM5) SWM, and 5% (SWH5), 10% (SWH10), and 15% (SWH15) SWH, respectively. The results showed that there were no significant differences in weight gain rate, feed conversion rate, survival rate, hepatosomatic index, and viscerosomatic index among the groups. The substitution of fish meal with SWH significantly augmented the serum triglyceride and total cholesterol levels, whereas urea nitrogen content exhibited a reduction proportional to the replacement ratio. The incorporation of SWH led to a notable rise in glutamate-pyruvate transaminase activity, albeit with a gradual decline as the substitution ratio escalated. Relative to the CON group, the SWH5 group displayed a significant reduction in serum superoxide dismutase activity and a significant elevation in serum catalase activity. The substitution of fish meal with SWM yielded noticeable increments in the activities of complement 3, immunoglobulin M, and alkaline phosphatase. Neither SWH nor SWM exerted a substantial influence on intestinal amylase activity. Regarding muscle characteristics, neither SWH nor SWM showed a marked effect on hardness and springiness; however, adhesiveness, cohesiveness, gumminess, and chewiness properties exhibited enhancement as the proportion of fish meal replacement increased. In conclusion, within this experimental context, substituting fish meal with SWH and SWM did not adversely impact the growth and meat quality of yellow catfish. Specifically, replacing 15% fish meal with stickwater hydrolysate and 5% fish meal with stickwater hydrolysate meal contributed to an enhanced immune capacity in yellow catfish to a certain extent.

The Effects of Fermented Feed on the Growth Performance, Antioxidant Activity, Immune Function, Intestinal Digestive Enzyme Activity, Morphology, and Microflora of Yellow-Feather Chickens.

This experiment was conducted to investigate the effects of fermented feed on growth performance, antioxidant activity, immune function, intestinal digestive enzyme activity, morphology, and microflora of yellow-feather chickens. A total of 240 one-day-old female yellow-feathered (Hexi dwarf) chickens were randomly divided into two treatment groups, with six replicates per group and 20 chickens per replicate. The control group (CK) received a basal diet, whereas the experimental group was fed a basal diet of +2.00% fermented feed (FJ). The trial lasted for 22 days. Compared with the CK, (1) the growth performance was not affected (p > 0.05); (2) immunoglobin a, immunoglobin g, immunoglobin m, interleukin-1β, and interleukin-6 were affected (p < 0.05); (3) liver superoxide dismutase, glutathione peroxidase, and catalase were higher (p < 0.05); (4) trypsin activity in the duodenum and cecal Shannon index were increased (p < 0.05); (5) the relative abundance of Actinobacteriota in cecum was increased (p < 0.05); (6) the abundance of dominant microflora of Bacteroides as well as Clostridia UCG-014_norank were increased (p < 0.05). In summary, the fermented feed improved the growth performance, antioxidant activity, immune function, intestinal digestive enzyme activity, morphology, and microflora of yellow-feather chickens.

Sodium butyrate improves the growth performance, intestinal immunity, and ammonia tolerance of yellow catfish Pelteobagrus fulvidraco by increasing the relative abundance of Candidatus_Arthromitus

The study aimed to analyze the effect of dietary sodium butyrate (SB) on intestinal digestive enzyme activity, liver physiological status, immune parameter, intestinal microbiota structure and composition, and ammonia tolerance in yellow catfish. Over the course of an 8-week experiment, four separate groups including 480 healthy male yellow catfish (1.52 ± 0.66 g) were fed diets containing varying concentrations of SB: 0, 0.05, 0.1, and 0.2%. Following this, an acute ammonia stress experiment that lasted for 96-h was conducted. The study showed that dietary supplementation of SB can improve growth performance and feed utilization (weight gain rate increased from 163.66 to 226.1%; specific growth rate increased from 1.73 to 2.11%/d; feed conversion rate decreased from 2.02 to 1.34), and increase intestinal digestive enzyme activity (lipase increased from 22.66 to 41.46 U/mg prot; amylase increased from 0.38 to 0.46 U/mg prot; pepsin increased from 10.13 to 12.83 U/mg prot). Plasma total protein (from 510.79 to 523.02 μg/mL), 50% hemolytic complement (from 35.46 to 40.46 U/mL), and immunoglobulin M (from 0.45 to 0.48 g/L) increased as dietary SB levels. On the contrary, plasma glucose (from 6.2 to 3.39 mmol/mL), high-density lipoprotein cholesterol (from 0.38 to 0.25 mmol/mL), aspartate aminotransferase (from 55.66 to 37.36 U/L), alanine aminotransferase (from 358.82 to 283.25 U/L), superoxide dismutase (from 163.84 to 147.13 U/mL), catalase (from 152.89 to 135.07 U/mL), tumor necrosis factor-α (from 67.58 to 62.13 pg/mL), interleukin-1 (from 40.07 to 30.96 pg/mL), and interleukin-8 (from 57.16 to 52.16 pg/mL) decreased with dietary SB levels. In addition, dietary supplementation of 0.2% SB significantly increased the relative abundance of Candidatus_Arthromitus in intestine by approximately 22-fold. To sum up, the utilization of SB has potential to enhance fish growth performance, elevate its physiological status, and improve its ability to tolerate acute ammonia toxicity. This is achievable by increasing the prevalence of Candidatus_Arthromitus in the intestine.

Effects of injecting L-Arginine on immune responses and intestinal structure of the hybrid grouper (Epinephelus fuscoguttatus ♀× Epinephelus lanceolatus ♂)

To study the effects of L-Arginine (Arg) on immune responses and intestinal structure in a hybrid grouper (Epinephelus fuscoguttatus ♀× Epinephelus lanceolatus ♂), intraperitoneal injection of different Arg doses (0, 50, 100, 200 mg per kg body weight of grouper) was administered once every seven days, repeating the process three times in the present study. A total of 216 groupers (initial weight of 349.42 ± 0.67 g) were randomly divided into four groups with three replicates, and each of the replicates comprised 18 fish. Serum was sampled at the seven, 14, and 21 days post-injection. The results showed that injection of Arg had a significant effect on serum albumin, immunoglobulin M (IgM), total protein (TP) and nitric oxide (NO) content, as well as nitric oxide synthase (NOS) and lysozyme activity (P < 0.05). With an increase of Arg dose, serum NO, TP, and albumin levels initially increased and subsequently decreased, and were significantly higher in fish injected with Arg at doses of 50 and 100 mg/kg in comparison to the control group. On days seven and 14, the highest serum albumin, TP, and IgM levels were observed in the 100 mg/kg group. With an increase in injection time and frequency, the 50 mg/kg group showed the optimal immune status after the third injection. Based on the results of the intestinal digestive enzyme activity and morphology, the injection of Arg at 50 mg/kg was the most beneficial, followed by the 100 mg/kg dose. Injection of 200 mg/kg Arg, especially after three injections, had adverse effects on immune responses and intestinal structure. These findings indicated that the intraperitoneal injection of L-Arg at a certain concentration can enhance the immunity and intestinal morphology of groupers. Notably, the most significant benefits were observed after three consecutive injections of Arg at 50 mg/kg in this experiment.