Digestive Enzyme Activities Research Articles

A novel multitrophic biofloc technology for duckweed and Megalobrama amblycephala integrated culture: Improving nutrient utilization and animal welfare

Biofloc technology (BFT) is an eco-friendly aquaculture model that utilizes zero-exchange water. In this study, we investigated the integration of duckweed into BFT in an effort to enhance nitrogen, phosphorus, and carbon utilization and to improve animal welfare for cultivating Megalobrama amblycephala. The experiment spanned 75 days, comparing a group of M. amblycephala supplemented with duckweed (DM) to a control group (CG) with no supplementation, where duckweed consumption relied solely on the feeding behavior of the fish. The concentrations of nitrate, total nitrogen, and phosphorus accumulation were lower in the DM than in the CG from day 45 onwards, with differences of 16.19, 26.90, and 1.45 mg/L, respectively, at the end of the experiment. The DM showed simultaneous increases of 5.77, 11.20, and 5.07 % in the absolute utilization of nitrogen, phosphorus, and carbon, respectively. The abundance of TM7a (10.27 %), linked to nitrate absorption, became the dominant genus in the water of the DM. Additionally, the abundance of Cetobacterium, associated with carbohydrate digestion, was significantly higher in gut of the DM (23.83 %) than in the gut of CG (1.24 %, P < 0.05). Supplementing the diet of M. amblycephala with duckweed improved digestion and antioxidant enzyme activity. Transcriptome data showed that duckweed supplementation resulted in an increase in the expression of genes related to protein digestion and absorption and carbohydrate metabolism in M. amblycephala, and analysis of the significantly enriched pathways further supported improved antioxidant capacity. Based on the above results, we concluded that as M. amblycephala consumes more duckweed, the differences in nitrogen and phosphorus levels between the DM and CG would continue to increase, along with a simultaneous increase in fixed carbon. Thus, this study achieved the goal of recycling BFT resources and improving animal welfare by integrating duckweed.

Effects of dietary β-sitosterol supplementation on growth performance, antioxidant ability, and disease resistance in largemouth bass Micropterus salmoides

β-sitosterol, as the most abundant phytosterol, has been shown to exert multiple biological roles in in vitro and in vivo animal studies. Largemouth bass (Micropterus salmoides) is an economical freshwater-farmed species widely cultivated in China due to its nutritious and delicious meat. This study investigated the effects of dietary β-sitosterol supplementation on largemouth bass farming. In the study, largemouth bass were fed with five levels of β-sitosterol (0, 20, 40, 80, and 160 mg/kg) supplementation in a commercial feed for four weeks. The growth performance, antioxidant ability, intestinal structure, immune-related gene expression, and resistance to pathogens such as Aeromonas hydrophila and largemouth bass virus (LMBRaV) were detected. The results revealed that β-sitosterol supplementation in feed increased the weight gain rate of largemouth bass, with 40 mg/kg supplementation displaying the best effect. The serum biochemical indices all showed an increase, including glucose and alkaline phosphatase. The intestinal villus length and muscularis propria thickness also increased, accompanied by elevated digestive enzyme activities, which promoted digestion and absorption of nutrients. Meanwhile, the levels of total cholesterol, aspartate aminotransferase, and alanine aminotransferase in serum decreased, indicating reduced liver damage. In addition, β-sitosterol supplementation effectively enhanced the antioxidant capacity of largemouth bass by decreasing malondialdehyde and elevating superoxide dismutase. Immune-related gene expression also changed. Pathogen infection tests revealed that β-sitosterol supplementation in feed had a certain protective effect against infection in largemouth bass, with the protection rate against A. hydrophila being higher than LMBRaV. The 40 mg/kg β-sitosterol supplementation group exhibited the best results. Collectively, the results revealed that the β-sitosterol can promote growth, improve enzyme activity, stimulate intestinal digestion, increase immune gene expression, and induce disease resistance in largemouth bass, with the optimal supplementation dosage being 40 mg/kg. β-sitosterol might be an excellent feed additive in aquaculture.

Effects of feed conditioning temperature on pellet quality, growth performance, intestinal development and blood parameters of geese from 1 to 28 d of age

A 28-d experiment was conducted to investigate the effects of feed-conditioning temperature on the pellet quality, growth performance, intestinal development, and blood parameters of geese. A total of 180 one-day-old White Yuzhou goslings were randomly allotted to 5 treatment groups, with 6 replicates containing 6 birds each. Five diets were conditioned at 65, 70, 75, 80, and 85°C. Body weight and feed intake per pen basis were recorded from the arrival to the end of the trial. Blood and small intestine samples were collected on d 28 for analysis. The results showed that the pellet durability index (PDI), pellet hardness, and gelatinisation degree of starch (GDS) increased with increasing conditioning temperature (P < 0.05). The final body weight (FBW), average daily gain (ADG) and average daily feed intake (ADFI) of goslings significantly increased when conditioning temperature increased from 65 or 70°C to 80 or 85°C (P < 0.05), accompanied by unaffected feed conversion ratio (FCR) (P > 0.05). The villus height to crypt depth ratio (VH/CD) in the duodenum and ileum improved with increasing conditioning temperature (P < 0.05). Additionally, trypsin and amylase activity were enhanced when the conditioning temperature increased from 65 to 85°C (P < 0.05). No significant differences in the carcass traits and blood parameters of goslings were observed among the groups (P > 0.05). Overall, under the present experimental conditions, increasing the steam-conditioning temperature of pelleted feed improved pellet quality, growth performance, intestinal morphology, and digestive enzyme activity in goslings. Based on broken-line regression analysis, the lower critical conditioning temperature for ADG in geese from 1 to 28 d of age was 80.95°C.

Effectiveness of lycopene dietary enrichment for growth performance, digestive enzymes, blood health, immunity, and antioxidant status of common carp (Cyprinus carpio) against chronic glyphosate toxicity

For food safety challenges, sustainable aquaculture emerges as a significant source in recent years; however, despite its potential, the industry still facing challenges, notably the exposure of cultured animals to pesticidal pollution. This pollution originating from agricultural practices that can enter aquaculture system directly: to integrated-agriculture aquaculture practices, or indirectly via soil leakage. Current research based on glyphosate (GLY) toxicity and its amelioration by lycopene (LYC). Four fish groups used for six-weeks experiment in which four groups were used. Control group (CL) was fed with basal commercial diet only without any LYC and GLY exposure; 2) LYC group: exposed to LYC supplemented diet (15 mg/kg per fish diet); 3) GLY group: exposed to glyphosate only (1/5th of 96 h LC50: 0.0892 mg/L) with basal commercial diet, and; 4) GLY + LYC group: exposed to both lycopene supplemented diet (15 mg/kg per fish diet) and glyphosate (1/5th of 96 h LC50: 0.0892 mg/L). GLY observed to decrease growth parameters and feed utilization whereas, lycopene ameliorated growth rate (WG, SGR, HSI, CF) and feeding utilization (FCR) as compared to the control group. Also, GLY induced toxicity within hematobiochemical parameters with alleviation by LYC supplementation. GLY induced cytotoxicity was observed within RBCs as lobbing, notching, vacuolation, blebbing, micronuclei, and condensation. Increase in reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS) were observed by GLY exposure. Also, there is observed reduction in antioxidant enzyme activities (CAT, SOD, POD, TPC and GSH) upon GLY exposure. Lipid peroxidation (malondialdehyde: MDA), 8-OHdG (8-hydroxy-2′-deoxyguanosine) and DIY (dityrosine) observed to increase by GLY toxicity. There was improvement in immune responses; increased AChE (acetylcholinesterase) activity, lysozyme content, ACP (acid phosphatase), NBT (nitro blue tetrazolium), NO (nitric oxide) and IgM levels (immunoglobulin M) and digestive enzyme activities (protease, lipase and amylase) observed by LYC supplemented diet. Taken together, LYC supplementation observed to alleviate GLY induced oxidative stress and cytotoxicity with improved immunity, digestive actions and blood health within C. carpio. Therefore, dietary supplementation with lycopene can protect common carp from the harmful effects by glyphosate within agri-integrated aquaculture practices, so suggesting it as potential feed additive.

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.

Growth performance, health status and flesh quality of striped catfish (Pangasianodon hypophthalmus) reared in variable stocking densities in biofloc system

Optimization of ideal stocking density in intensive aquaculture system is a challenging appraisal. Higher stocking density is inducing chronic stress, impacting negatively on physiology and increasing disease associated risks in fish. Hence, the study was designed to evaluate the water quality, growth performance, health status and flesh quality of striped catfish (Pangasianodon hypophthalmus). The fish (2.61–2.64 ± 0.01 g initial body weight) were reared in randomly designed variable stocking densities (SDs) including five treatments (30, 40, 50, 60 and 70 fish m−3) in triplicates at C:N ratio 15:1 in jaggery supplemented biofloc system for 120 days in 1000 –L experimental fiber-reinforced plastic tanks. SD30 acted as control treatment having low stocking density. During the culture, pH, alkalinity and dissolved oxygen level decreased and BOD increased with increased stocking density. TDS and TSS level increased upto SD50 treatment and further decreased in higher stocking density treatments. Higher population of heterotrophic, ammonifying and nitrifying bacteria significantly (p < 0.05) reduced TAN, NH3-N, NO2-N, and elevated NO3-Nas well as rate and potential of ammonification and nitrification in SD50 treatment than other treatments. Bacillariophyceae and protozoa were most dominant group in the biofloc microbiome in all the treatments. Highly elevated biofloc volume, floc microbiome, good floc characteristics and floc quality might have enhanced fish survival rate, body weight gain, SGR through improving FCR in SD50 than other SDs. Moreover, higher population of gut microbiota (TPC and probiotic) and elevated digestive enzymes activity in fish reared in SD50 treatment significantly (p < 0.05) enhanced PER, ANPU, and somatic indices (GSI and HSI) as well as enhanced colour (lightness, yellowness/blueness and whiteness), flesh quality and hardness. Fish reared in SD50 treatment showed significantly (p < 0.05) higher haematological (TEC, TLC and Hb), immunological (TSP, albumin, RBA and lysozyme), antioxidant responses (higher SOD and CAT) and lower metabolic stress enzymes responses (ALT, AST and glucose). Moreover, fish reared in SD50 treatment showed improved villi surface area and height in intestine and slightly vacuolated hepatocytes in liver. Overall, significantly (p < 0.05) better water quality, fish performance, health status and flesh quality were observed in SD50. Collectively, the findings suggest that farmers can be benefitted by fetching higher production through suitable stocking density (50fish m−3) of P. hypophthalmus in biofloc with improved water quality, growth performance, health status and flesh quality.

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.

Changes in Digestive Enzyme Activities during Larval Development of Spotted Seatrout (Cynoscion nebulosus)

The spotted seatrout (Cynoscion nebulosus)—an important commercial species—has a high potential for aquaculture in the Gulf of Mexico. To optimize its feeding during larval rearing, this study aims to evaluate the primary gastric (pepsin), intestinal (leucine aminopeptidase and alkaline phosphatase), and pancreatic (alkaline protease, trypsin, chymotrypsin, amylase, and lipase) enzyme activities from hatching to day 30. A multivariate analysis identified three digestive enzyme development stages during the spotted seatrout larval transformation. The first stage occurred between 1 (mean ± standard error (SE) = 1.73 ± 0.14 millimeter (mm) standard length (SL)) and 3 (2.14 ± 0.07 mm SL) days after hatching (DAH); a period of digestive stability showed the highest activity in amylase and bile salt-dependent lipase. The second stage (from 4 (2.53 ± 0.09 mm SL) to 20 (10.92 ± 0.51 mm SL) DAH) was a period of digestive transition, during which leucine aminopeptidase, chymotrypsin, and alkaline proteases were identified as the predominant enzymes from 4 to 5 DAH. In the third stage—a period of digestive stability—pepsin was the major enzyme that occurred between 25 (16.51 ± 0.81 mm SL) and 30 (25.91 ± 0.82 mm SL) DAH. These results indicate that the spotted seatrout larvae have a digestive system adapted to lipids and carbohydrates at the onset of feeding, with an immediate transition to protein digestion when exogenous feeding begins. Additionally, the digestive system of the spotted seatrout may be considered mature at 25 DAH. Further research is needed to elucidate the mechanisms of digestive tract development in the spotted seatrout larvae.

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.

Effect of temporal thermal stress on Penaeus vannamei: Growth performance and physiological plasticity.

The present study evaluated the effect of temporal periods of hypothermia and hyperthermia, followed by an optimal temperature recovery phase on the growth, survival, and physiological response of Penaeus vannamei. Post-larvae were exposed to stress periods for 7 and 14 days at 22 °C and 32 °C each, followed by a recovery phase at 28 °C to complete seven experimental weeks, and were compared with a control group maintained at 28 °C. Weight gain, specific growth rate, feed intake, feed conversion ratio, and survival were weekly determined. Muscle, hepatopancreas, and hemolymph were sampled on the 14th day of the recovery phase for biochemical composition, and antioxidant and digestive enzyme activities determination. The shrimp presented a higher growth rate during short-term hyperthermia in contrast to shrimp under hypothermia that presented compensatory growth after thermal stress when the temperature was restored at 28 °C. Hyperthermia increased 12–13% the feed intake while this was diminished 21–29% by the hypothermia periods. Shrimp undergo metabolic adjustments following thermal stress, with short hypothermia increasing the lipase activity and lipid storage in the hepatopancreas, while short hyperthermia also enhances chymotrypsin activity and leads to higher protein and lipid accumulation. Conversely, prolonged hyperthermia induces greater energy consumption, depleting lipid and glycogen stores, while hypothermia causes scarce mobilization of energy reserves during recovery phase. Antioxidant enzyme activities were not affected by short-thermal stress (7d), while prolonged thermal stress (14d) significantly affected SOD, CAT, and GPx activities. The present study provides important insights into the physiological plasticity of P. vannamei during recovery from thermal stress.

Recuperative Effects of Cinnamon (Cinnamomum zeylanicum) in Catla catla After Sub-Lethal Exposure to Lead.

This research was conducted to validate the beneficial effects of incorporating dietary cinnamon (Cinnamomum zeylanicum) powder (CzP) in alleviating lead (Pb) poisoning in fish. Healthy Catla catla individuals (16.36 ± 0.19g/fish) were distributed across 18 tanks in triplicate groups. The experimental groups were as follows: Control group: fish without supplementation or exposure to Pb; positive control group: fish without supplementation but exposed to 1mg/L Pb; 5g/kg CzP along with 1mg/L Pb exposure; 10g/kg CzP along with 1mg/L Pb exposure; 15g/kg CzP along with 1mg/L Pb exposure; and 20g/kg CzP along with 1mg/L Pb exposure. The trial continued for a period of 60days. Waterborne Pb had a deleterious effect on fish growth performance, body composition, blood profile, and digestive enzyme activity, along with elevated Pb accumulation in various tissues. Conversely, consumption of cinnamon effectively mitigated the toxic potential of Pb and enhanced fish longevity. Notably, 10g/kg CzP boosted growth, improved carcass quality, reversed blood indices, restored enzyme function in the gut, and mitigated Pb accumulation in tissues. In summary, the findings revealed that incorporating 10g/kg of CzP as a dietary supplement in C. catla aquaculture could effectively counteract heavy metal toxicity.

Influence of Herba Houttuyniae added to fodder on the morphological structure of the intestinal tract, the digestive enzymes, the intestinal flora, and immune function of koi carp (Cyprinus carpio) infected with Aeromonas veronii.

This study investigated whether adding Herba Houttuyniae to feed can improve intestinal function and prevent diseases for koi carp (Cyprinus carpio) infected with Aeromonas veronii. There was a total of 168 koi carp with an average body length of (9.43 ± 0.99) cm and an average body weight of (26.00 ± 11.40) g. The K group was the control group fed with basal feed, while the C group was fed with feed with a H. houttuyniae content of six per thousand. After 14days of feeding, the fish were fasted for a day and then intraperitoneally injected with A. veronii for artificial infection, injection dose is 0.2mL, and the concentration is 1 × 107CFU/mL. Samples were collected from the two groups on days 0, 1, 2, and 4. The fold height, intestinal villus width, and muscle layer thickness in the gut of the koi carp were measured. In addition, on day 4, the activities of trypsin, α-amylase, and lipase in the gut were determined, and the intestinal flora of the carp in both groups was tested. The results showed that on the second and fourth days of sampling, the fold height and muscle layer thickness in the C group were significantly higher than those in the K group (P < 0.05). The villus width in the C group was slightly higher than that in the K group, but the difference was not significant (P > 0.05). Microscopic observation revealed that the intestinal structure of the carp in the C4 (day 4 in C group) group was more intact than that in the K4 (day 4 in K group) group. Moreover, the activities of trypsin, α-amylase, and lipase in the foregut and midgut in the C4 group were higher than those in the K4 group (P < 0.05). The activities of trypsin and α-amylase in the hindgut in the C4 group were higher than those in the K4 group (P < 0.05). Furthermore, beneficial bacteria, especially those in the genus Cetobacterium, were more abundant in the intestinal tract of the carp in the C4 group compared to the K group. In addition, comparisons and tests of IL-4 and IL-10 in the intestines of the fish in both groups demonstrated that the H. houttuyniae added to feed enhanced the immune function of the fish intestines after bacterial attack. In conclusion, for koi carp infected with A.veronii, adding H. houttuyniae to their feed not only improves the activity of digestive enzymes and the morphological structure of the intestine but also optimizes the beneficial intestinal microbiota, thereby protecting the intestinal tract.

Exploring the relationship between dietary rapeseed meal, condensed tannin and growth, nutrive metabolism in largemouth bass (Micropterus salmoides)

This study evaluated the effects of rapeseed meal (RM) and condensed tannin (CT) on the growth and nutritional metabolism of largemouth bass (Micropterus salmoides), and speculated whether there was interaction between anti-nutritional factors in RM. Eight diets were formulated for 55-day feeding trial, six of which were practical diet groups, including control group (CG), five RM inclusive groups with graded RM levels of 5% (RM5), 10% (RM10), 15% (RM15), 20% (RM20) and 25% (RM25) partially replacing fishmeal, and the other two were semi-purified diets with 0.062% CT (CT5) ≈ the CT content in the RM5 and 0.31% CT (CT25) ≈ the CT content in the RM25. The results of the experiments on replacing fishmeal with RM demonstrated that with the increase of RM substitution level, the weight gain rate (WGR), survival rate (SR) and specific growth rate (SGR) of largemouth bass showed a downward trend. High levels of RM led to the inhibition of digestive enzyme activity in largemouth bass, as well as the manifestation of abnormal markers related to protein, fat, and carbohydrate metabolism in both plasma and liver. RM reduced muscle protein and fat content, although the effect was not statistically significant at 5% RM level. The results of CT concentration experiments showed that the addition of 0.31% CT significantly reduced WGR, SGR, SR, protein efficiency ratio (PER) and gastrointestinal digestive enzyme activity, and significantly increased the feed coefficient ratio (FCR), plasma ammonia (PA), plasma glucose (PG), and hepatic glycogen (HG) and liver triglyceride (TG). The addition of 0.062% CT significantly reduced PG and HG. Supplementation of CT significantly reduced muscle fat. Among the groups of CT supplementation and RM, CT5 exhibited superior WGR, PER and FCR compared to RM5, along with enhanced intestinal trypsin, amylase activity, liver glutamic pyruvic transaminase (GPT) activity and decreased content of HG and liver TG; CT25 exhibited decreased activities of gastric lipase (LPS), enteric trypsin and pepsin, and increased content of total cholesterol (T-CHO) and glucose in plasma in compariosn to RM25, accompanied with no significant change in growth performance. Therefore, largemouth bass exhibited tolerance to a 5% inclusion of RM in the feed without compromising their growth, digestion and metabolic functions. The incorporation of 5% RM, equivalent to a supplemental 0.062% CT, had regulatory effects on the digestion and metabolism of largemouth bass while improving feed utilization. There was an interaction among anti-nutritional factors in RM, with synergistic effect being evident at low RM levels, whereas antagonism more promient at high levels of RM.

Comparative analysis of efficacy of different forms of Galli Gigerii Endothelium Corneum on functional dyspepsia in rats based on composition-pharmacodynamics

A systematic evaluation of the differences in the chemical composition and efficacy of the different forms of Galli Gigerii Endothelium Corneum(GGEC) was conducted based on modern analytical techniques and a functional dyspepsia(FD) rat model, which clarifies the material basis of the digestive efficacy of GGEC. Proteins, enzymes, polysaccharides, amino acids, and flavonoids in GGEC powder and decoction were determined respectively. The total protein of the powder and decoction was 0.06% and 0.65%, respectively, and the pepsin and amylase potency of the powder was 27.03 and 44.05 U·mg~(-1) respectively. The polysaccharide of the decoction was 0.03%, and there was no polysaccharide detected in the powder. The total L-type amino acids in the powder and decoction were 279.81 and 8.27 mg·g~(-1) respectively, and the total flavonoid content was 59.51 μg·g~(-1). Enzymes and flavonoids were not detected in the decoction. The powder significantly reduced nutrient paste viscosity, while the decoction and control group showed no significant reduction in nutrient paste viscosity. FD rat models were prepared by iodoacetamide gavage and irregular diet. The results showed that both powder and decoction significantly increased the gastric emptying effect, small intestinal propulsion rate, digestive enzymes activity, gastrin(GAS), motilin(MTL), ghrelin(GHRL) and reduced vasoactive intestinal peptide(VIP), 3-(2-ammo-nioethyl)-5-hydroxy-1H-indolium maleate(5-HT), and somatostatin(SST) content in rats(P&lt;0.05, P&lt;0.01). Comparison of GGEC decoction and powder administration between groups of the same dosage level showed that gastrointestinal propulsion and serum levels of GAS, GHRL, VIP, and SST in the powder group were significantly superior to those in the decoction and that the gastrointestinal propulsion, as well as serum levels of MTL, GAS, and GHRL were slightly higher than those of the decoction with two times its raw dose, and the serum levels of SST, 5-HT, and VIP in the powder group were slightly lower than those of the decoction with two times its raw dose. In conclusion, both decoction and powder have therapeutic effects on FD, but there is a significant difference between the two effects. Under the same dosage, the digestive efficacy of the powder is significantly better than that of the decoction, and the decoction needs to increase the dosage to compensate for the efficacy. It is hypothesized that the digestive efficacy of the GGEC has a duality, and the digestive active ingredients of the powder may include enzymes and L-type amino acids, while the decoction mainly relies on L-type amino acids to exert its efficacy. This study provides new evidence to investigate the digestive active substances of the GGEC and to improve the effectiveness of the drug in the clinic.

Diet Shifts Alter the Activity and Distribution of Digestive Enzymes in an Herbivorous Fish

The digestive tract is central to the function of an animal since it assimilates nutrients from the diet. Digestion itself is a chemical process and digestive enzymes are the digestive catalysts. Thus, we measured amylase, maltase, N-acetyl-b-d-glucosaminidase, lipase, trypsin, aminopeptidase, and alkaline phosphatase activities along the digestive tract of the marine herbivorous fish, Cebidichthys violaceus. We did this for wild-caught individuals of this species, and compared those to individuals fed carnivore, omnivore, and herbivore diets in the laboratory for six months. In laboratory fish, the enzymatic activities were generally lower compared to wild-caught fish. In wild caught fish, a strong anterior-to-posterior gradient of amylase activity was observed along the gut and this pattern largely disappeared in the lab-fed fish. N-acetyl-β-D-glucosaminidase (NAGase), which breaks down chitin products, showed an increase in activity in the distal intestines of the lab-fed fish, which is not observed in wild fish. The NAGase activity of the herbivorous fishes correlate with the bacterial species Paroccus sp., which is a known NAGase producer, and one of the dominant microbes in the distal intestines of the lab-fed fish. The role of this enzyme, however, remains unclear since the lab diets did not contain large amounts of chitin. These enzymatic differences tell us how much fish can modify their enzymatic activity to align with their diet. In summary, the findings show that C. violaceous can endure different degrees of protein and carbohydrate levels, within limits. Their digestive system clearly changed in response to more protein in the diet, along with a microbiome that had more potential pathogens. Live algal diets would may be the most suitable for this herbivorous fish based on the totality of gathered data from the lab. American Physiological Society Fellowship UCI Microbiome Initiative Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of replacing fish meal with biofloc meal on growth performance, nutrients metabolism, immune response and intestinal microbiota of common carp (Cyprinus carpio)

This study investigated the effects of replacing fish meal (FM) with biofloc meal (BM) on the growth, digestion function, protein metabolism, lipid metabolism, immunity, antioxidant capacity and intestinal microbiota of common carp (Cyprinus carpio). The experiment includes two trials (a growth trial and a digestibility trial). In the growth trial, the control diet contained 20% FM. And five isonitrogenous and isolipidic diets were formulated to replace 0% (CK), 20% (BM20), 40% (BM40), 60% (BM60) and 80% (BM80) of the FM protein with BM. The five diets were fed to common carp (3.73 ± 0.01 g) for 56 days. The results indicated that the growth performance [final weight (FW), specific growth rate (SGR) and feed efficiency ratio (FER)] and digestive enzymes activities displayed a noteworthy quadratic trend with the increasing replacement level of FM with BM (P < 0.05), reaching a maximum at the BM40 group and a minimum at the BM80 group. Regression analysis of weight gain rate (WGR) against the substitution level found that the optimal level of BM replacing FM was 34.12%. The appropriate levels of BM could improve protein metabolism and lipid metabolism by regulating the expressions of related genes. Regarding the expression levels of PI3K, mTOR and HSL mRNA, they were the highest in the BM40 group and the lowest in the BM80 group, while the levels of ACC and FAS mRNA were reversed (P < 0.05). Simultaneously, the number of lipid vacuoles in the BM80 group were significantly increased than the CK group. Replacing 40% FM with BM augmented the fish immunity and antioxidant capacity, as showed by elevated the C3, C4 and IgM levels as well as CAT and SOD activities, and reduced the expression levels of NF-κB, TNF-α and Keap1 (P < 0.05). Regarding intestinal microbiota, replacing 40% FM with BM could improve the intestinal microbiota structure. The digestibility trial results showed that the apparent digestibility of protein and lipid in BM of common carp was slightly lower than FM. Conclusively, replacing 40% FM with BM could promote growth, immunity and protein metabolism of common carp, but excessive substitution level (80%) could compromise growth and hepatopancreas health.

Effect of water temperature on the development of Portunus trituberculatus larvae in the off-season breeding mode (Decapoda, Portunidae)

Abstract To clarify the influence of different water temperatures on the development of Portunus trituberculatus (swimming crab) larvae during off-season (early autumn) breeding, a gradient of four rearing temperatures of 27, 29, 31 and 33°C was set up, and the effects of water temperature on larval development were systematically compared. The results showed that the moulting cycle (MC) from the zoea 1 (Z1)-zoea 2 (Z2) stage was not significantly affected by water temperature (), remaining at approximately 3 days. However, in the Z2-megalopa (M) stage, the MC in the 31°C group was consistently the shortest. The total developmental duration and total effective cumulative temperature during Z1-M in the 31°C group were the lowest at 9.97 days and 250 days · °C, respectively. According to the equation of water temperature and larval development rate, the development rate was the fastest when the water temperature was 31°C. As the water temperature increased, the survival rate (SR) of larvae at various stages gradually decreased. The SR of the 27°C group was consistently significantly higher than that of the 33°C group (), especially in the M stage, where the SR of the 33°C group was only 2%, which was significantly lower than that of the 27°C and 29°C groups (). Among the antioxidant indexes, both superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) were the lowest in the 29°C group at 315.75 U/mg protein and 0.36 mmol/g protein, respectively, and both were significantly lower than those in the 33°C group (). Catalase (CAT) and glutathione peroxidase (GSH-PX) were both the lowest in the 31°C group, and in this group the CAT was significantly lower than in the 33°C group, and GSH-PX was significantly lower than in the 27°C group (). For malondialdehyde (MDA) content, the four groups were basically maintained at about 2.5 nmol/mg protein, and there was no significant difference (). In terms of digestive enzyme activity, the activity of lipase (LPS) was basically maintained at 1.93 U/g protein. The other four digestive enzyme activity differences were mainly reflected in that the 31 and 33°C groups maintained relatively higher levels than the 27 and 29°C groups, especially the activities of α-amylase (AMS), and cellulase (CL) in the 33°C group, which were significantly higher than those in the 27 and 29°C groups (). Comprehensive indicators indicate that a water temperature between 29 and 31°C is the appropriate temperature for the development of the larvae of off-season breeding swimming crabs.

Changes in growth, morphology, and levels of digestive enzymes and growth-related hormones in early ontogeny of black scraper, Thamnaconus modestus

IntroductionThe black scraper, Thamnaconus modestus, is a highly valued marine fish species, but its output has gradually decreased in recent years, which may be due to its low survival rate during early ontogenesis.MethodsTherefore, in this study, we assessed the changes in growth, morphology, digestive enzymes, and hormone levels in T. modestus from 0–60 days post-hatching (dph) and revealed growth turning points by morphological measurement and determination of digestive enzyme activities and hormone levels. We found that ontogenesis could be divided into the larval (0–20 dph) and juvenile (20–60 dph) stages. Acid and alkaline protease activity significantly increased and decreased, respectively, from 12–25 dph, likely due to the development of stomach and gastric glands. Acid phosphatase levels significantly increased at 0 and 4 dph, which may be related to the regulation of metabolism and immune protection. A sharp increase in alkaline phosphatase levels at 20 and 25 dph was observed and was likely due to the development of the brush border membrane of enterocytes. The amylase level was significantly higher at 25, 30, and 35 dph, possibly due to better digestion and absorption during the transition from consuming Artemia to compound feed. In newly hatched larvae, the level of thyroid hormones triiodothyronine (T3) and thyroxine (T4) gradually increased and peaked at 35 dph, highlighting the importance of these hormones during the development of T. modestus. Growth hormone (GH) levels first increased from 0–8 dph, with a plateau at 8–20 dph, and then increased at 25–30–35 dph. For insulin-like growth factor 1 (IGF-1), a significant increase with a subsequent plateau was observed between 8 and 20 dph, followed by a substantial decrease between 30 and 35 dph. These results suggest that the regulating functions of GH and IGF-1 are synchronised. Digestive enzyme activity and hormone levels of abnormal fry at 30 dph were lower than those of normal fish, highlighting the importance of specific hormones, especially T4 and IGF-1, in the development of T. modestus.

The performance and physiological responses of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) to different sorghum cultivars

Utilizing pest-resistant cultivars is a highly effective and environmentally-friendly approach for managing crop infestations by pests. In the present study, the differences in the resistance of eight cultivars of Sorghum bicolor (L.) Moench (Kimia, Payam, Pegah, Sepideh, Spidfid, KGS23, KFS2, and KFS18) against Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), a polyphagous pest of stored products, were evaluated based on demographic parameters, nutritional indices, and digestive enzymatic activities within the pest. The results revealed that the development time of R. dominica was the shortest when reared on Kimia, Spidfid, and KFS2, while the longest was recorded in those fed on Payam and Pegah. The fecundity of R. dominica was the lowest on Pegah. Furthermore, Kimia and Sepideh showed the highest intrinsic rate of increase (r) and finite rate of increase (λ), whereas the lowest values for these parameters were observed on Pegah and KGS23. The highest relative growth rate (RGR) of R. dominica was achieved on Sepideh, whereas the lowest RGR was observed on KGS23. The highest level of digestive proteolytic activity in R. dominica was observed on Sepideh, whereas the lowest level was found on KGS23. The amylolytic activity in R. dominica was the highest on Sepideh, and the lowest on Pegah and KGS23. The findings showed significant negative correlations between fecundity, intrinsic rate of increase, and amylolytic activity of the pest with the total phenolic content of the studied sorghum cultivars. Furthermore, the results obtained from cluster analysis revealed that Sepideh, Kimia, and KFS2 were the susceptible cultivars for population growth of R. dominica, while Payam, Pegah, and KGS23 were the partially resistant hosts for this pest. The pest-resistant sorghum cultivars identified in this study can potentially be utilized in combination with other pest control strategies for sustainable management of R. dominica, which may help reduce the excessive use of chemical insecticides.

The use of fishery and aquaculture by-products with Nannochloropsis sp. allows total dietary replacement of wild-caught fishmeal, fish oil and soy protein in European sea bass juveniles

Five experimental diets (CTRL, 50FMFO, 50FMFO-50MIC, 0FMFO-50MIC, 0FMFO-100MIC) were formulated to replace wild-caught fishmeal (FM), wild-caught fish oil (FO) and soy protein using fisheries, aquaculture by-products (BP) and microalgae (MIC). Fifty European sea bass juveniles were distributed in 15 tanks (initial body weight 46.66 ± 0.04 g) and reared in a recirculating aquaculture system for 88 days. Temperature, salinity, oxygen and photoperiod were kept constant throughout the experiment (22 ± 0.5 °C, 25 g L−1 and 8.0 ± 1.0 mg L−1, 12:12 light/dark, respectively). Growth, feed intake (FI), proximal composition, nutritional index, apparent digestibility, somatometric indexes, blood plasma biochemistry and digestive enzyme activity were evaluated. Also, gut microbiota composition was assessed through next-generation sequencing. Results showed that growth performance and feed digestibility were not affected by FM, FO and soy replacement using BP and MIC. Dietary replacement of 100% FM and FO with circular substitutes and 50% replacement of soymeal with microalgae increased the activity of alkaline phosphatase and chymotrypsin. Moreover, the inclusion of BP and MIC had positive effects on the gut microbiota richness and abundance. In conclusion, the utilization of BP and MIC represents a valuable alternative to FM and FO as well as soy protein in feed for European sea bass juveniles.