Feeding and osmoregulation in the euryhaline crab Neohelice granulata: digestive parameter responses

Effect of biological additives on Japanese eel (Anguilla japonica) growth performance, digestive enzymes activity and immunology

Effects of Dietary Metabolizable Energy and Crude Protein Content on the Activities of Digestive Enzymes in Jejunal Fluid of Peking Ducks

Microplastics alter digestive enzyme activities in the marine bivalve, Mytilus galloprovincialis.

Combined effects of toxic Microcystis aeruginosa and hypoxia on the digestive enzyme activities of the triangle sail mussel Hyriopsis cumingii

The silkworm (Bombyx mori) is an economically important insect and serves as a model organism for Lepidoptera. To investigate the effects of the intestinal microbial population on the growth and development of larvae fed an artificial diet (AD) during the young stages, we analyzed the characteristics of the intestinal microbial population using 16S rRNA gene sequencing technology. Our results revealed that the intestinal flora of the AD group tended to be simple by the 3rd-instar, which Lactobacillus accounting for 14.85% and leading to a decreased pH in the intestinal fluid. In contrast, the intestinal flora of silkworms in the mulberry leaf (ML) group showed continuous growth of diversity, with Proteobacteria accounting for 37.10%, Firmicutes accounting for 21.44%, and Actinobacteria accounting for 17.36%. Additionally, we detected the activity of intestinal digestive enzymes at different instars and found that the activity of digestive enzymes in the AD group increased by larval instar. Protease activity in the AD group was lower during the 1st- to 3rd-instars compared to the ML group, while α-amylase and lipase activities were significantly higher in the AD group during the 2nd- and 3rd-instar compared to the ML group. Furthermore, our experimental results indicated that changes in the intestinal population decreased the pH and affected the activity of proteases, which might contribute to the slower growth and development of larvae in the AD group. In summary, this study provides a reference for investigating the relationship between artificial diet and intestinal flora balance.

The use of probiotics has become an alternative in the aquaculture industry and is considered a new tool for disease control. However, the maintenance of viability of probiotic bacterial cells during storage is quite challenging. This study aimed to investigate the potential effects of euryhaline probiotic and paraprobiotic B. cereus BR2 on African catfish, specifically on growth performance, gastrointestinal health, immune-related gene expression, and resistance to E. tarda ETS1.1. The test feed was enriched with a 1% (w/w) dose of probiotics and paraprobiotics at a cells density of 108 and 1010 CFU mL− 1, each with replications. For diet supplementation experiment, African catfish fry with initial average body weight of 6.67 ± 0.34 g were randomly placed into six aquaria containing 60 L volume of freshwater and reared for 30 days. Afterwards, fish were challenged intraperitoneally on day 31− th with E. tarda ETS1.1 at cell density of 107 CFU mL− 1, and reared for 14 days. The results showed that diets treated with probiotics and paraprobiotics 108 and 1010 CFU mL− 1 significantly (p < 0.05) increased mean final weight, mean final biomass, specific growth rate (SGR), disease resistance (survival rate) and reduced feed conversion ratio (FCR) values. Digestive enzyme (amylase, protease, lipase) activities, total bacterial population and abundance of B. cereus BR2 in the intestine were measured higher in supplementation treatments than control fish. After the challenge test, decreased E. tarda ETS1.1 abundance in kidney and liver of fish were measured in both probiotic and paraprobiotic treatments. Furthermore, interleukin 1β (IL-1β) gene expression showed upregulation in fish after treatment. Similarly, major histocompatibility complex 2β (MHC-2β) expression was significantly upregulated after supplementation and post-challenge, with the highest level of MHC-2β mRNA expression found in DPI 7. The supplementation of probiotic and paraprobiotic B. cereus BR2 per oral effectively improved growth performance, digestive enzymes activity, immune-related gene expression, resistance of African catfish to E. tarda ETS1.1.

This trial was conducted to investigate the effects of proanthocyanidins (PACs) on the growth performance, digestive enzymes activities and microbiota in the intestines of juvenile American eels (Anguilla rostrata) cultured in cement tanks. Six cement tanks stocked with similar fish size and weight (about 120 g/fish and 2116 kg/tank) were randomly divided into a control group fed with a commercial diet and a PACs group fed with a commercial diet supplemented 400 mg/kg PACs, with three replicates in each group. The trial period lasted 60 days. The finial fish weight and weight gain rate were significantly improved by PACs supplementation (P<0.05). There were no significant differences in feed efficiency and feeding rate between the control group and PACs group (P>0.05). Activities of protease in intestines were significantly enhanced by PACs supplementation (P<0.05), however dietary PACs supplementation had no significant effect on the activities of amylase and lipase (P>0.05). Furthermore, dietary PACs supplementation increased the richness and decrease the diversity of intestinal microbiota. At the phylum level, the higher relative abundance of Proteobacteria and the lower relative abundances of Firmicutes and Actinobacteria were found in PACs group compared to control group. At the genus level, PACs supplemented in diet significantly increased the relative abundances of Candidatus Arthromitus, Paracoccus and Eubacterium hallii (P>0.05). In conclusion, dietary 400 mg/kg PACs supplementation improved growth performance and activity of protease in intestine, and modulate intestinal microbiota of juvenile American eel cultured in cement tanks.

Simple SummarySustainable aquaculture requires natural alternative substances with high potential in enhancing the performance and wellbeing of aquatic animals. In this regard, the present study tested the possibility of using mannan oligosaccharides (MOS) in the diets of grey mullet as functional additives. For 8 weeks, fish were fed with enriched diets containing 0, 0.5, 1, and 2% MOS. The results showed marked improvements in the growth performance, digestive enzyme activity, blood chemistry, and antioxidative capacity. In conclusion, dietary MOS at 0.5–1% is required to enhance the productivity of grey mullet.Mannan oligosaccharide (MOS) is prebiotic with high functionality in aquaculture. The current study investigated the potential roles of MOS on the growth performance, digestive enzyme activity, carcass composition, and blood chemistry of Thinlip grey mullet (Liza ramada). Four tested diets with 34.49% crude protein and 6.29% of total lipids were prepared and fortified with 0, 0.5, 1, and 2% MOS. Fish of initial weight = 5.14 ± 0.11 g/fish were distributed in 12 hapas (0.5 × 0.5 × 1 m) at 15 fish per hapa (triplicates) and fed the test diets to the satiation level two times a day (08:00 and 15:00) for eight weeks. At the end of the trial, all fish were weighed individually for growth performance calculation. Blood was collected to check blood chemistry traits, and intestines were dissected for digestive enzyme analysis. Fish treated with MOS had marked enhancement in the final body weight, feed conversion ratio, protein gain, and protein retention regardless of inclusion dose (p < 0.05). The weight gain, specific growth rate, and protein efficiency ratio were meaningfully enhanced by including MOS at 0.5 and 1%, followed by fish fed with 2% MOS, while the lowest values were in the control group (p < 0.05). Insignificant influences of MOS were seen on the chemical composition of carcass components (moisture, crude protein, total lipids, and ash) (p > 0.05). Fish treated with MOS at 0.5 and 1% had marked enhancement in the amylase, lipase, and protease activities regardless of inclusion dose (p < 0.05). The blood total protein and albumin levels were meaningfully enhanced by including MOS at 0.5 and 1%, followed by fish fed with 2% MOS, while the lowest values were in the control group (p < 0.05). The blood globulin was significantly enhanced in fish fed 1% MOS than fish treated with 0, 0.5, and 2% of MOS (p < 0.05). The blood lysozyme activity was meaningfully enhanced by including MOS at 1%, followed by fish treated with 0.5 and 2%, while the lowest values were in the control group (p < 0.05). Phagocytic activity and phagocytic index were markedly improved in fish treated with 1 and 2% MOS, followed by those fed 0.5% compared with fish fed MOS-free diet (p < 0.05). Superoxide dismutase and glutathione peroxidase were markedly improved in fish treated with 1, and 2% MOS, followed by those fed 0.5% compared with fish fed MOS-free diet (p < 0.05). Dietary MOS (0.5, 1, and 2%) meaningfully enhanced catalase activity while decreased the malondialdehyde concentration (p < 0.05). In summary, dietary MOS is required at 0.5–1% for enhancing the growth rate, feed efficiency, digestive enzyme activity, blood chemistry, and antioxidative capacity of grey mullet.

This study was conducted to evaluate the effects of mannan oligosaccharide (MOS) dietary supplementation on growth, digestive enzyme activities, gut morphology, and microbiota in striped catfish (Pangasianodon hypophthalmus). Triplicate groups of juvenile striped catfish (initial weight 20.41 ± 1.64 g) were fed twice per day at 2.5 % of body weight for 12 weeks, with 0 (control), 0.2, 0.4, 0.6, or 0.8 % MOS diets. Compared to control (0.74 ± 0.03) and fish fed low MOS concentration, those fed 0.6 % (1.01 ± 0.02) or 0.8 % (1.03 ± 0.03) MOS had significantly higher (P < 0.05) specific growth rates. Feed conversion ratio and protein efficiency ratio, respectively, significantly improved (P < 0.05) in fish fed 0.6 % (1.62 ± 0.23; 1.71 ± 0.23) or 0.8 % (1.42 ± 0.06; 1.92 ± 0.08) MOS. Further, compared to control and fish fed 0.2 % MOS, those fed 0.6 % MOS had significantly higher (P < 0.05) apparent protein and dry matter digestibilities. Amylase, protease, and lipase activities, respectively, were significantly higher (P < 0.05) in fish fed 0.6 % MOS (5.10 ± 0.97; 0.47 ± 0.08; and 5.59 ± 1.82) than in control (2.60 ± 0.53; 0.32 ± 0.05; and 3.78 ± 0.72). Histological analysis of the anterior and posterior gut showed significantly higher (P < 0.05) villus length in 0.6 and 0.8 % MOS fed fish than in the control and other treatments. The guts of fish fed different MOS concentrations showed similar total lactic acid bacteria counts, which were significantly higher (P < 0.05) than those in the control. Thus, 0.6 % MOS-supplemented diet improved growth, feed utilization, digestive enzyme activities, gut morphology, and microbiota in juvenile striped catfish.

Effect of probiotic on larvae shrimp ( Penaeus vannamei) based on water quality, survival rate and digestive enzyme activities

We examined seasonal and age-related variation in digestive organ sizes and enzyme activities in female western sandpipers (Calidris mauri) refueling at a coastal stopover site in southern British Columbia. Adult sandpipers exhibited seasonal variation in pancreatic and intestinal enzyme activities but not in digestive system or organ sizes. Spring migrants had 22% higher total and 67% higher standardized pancreatic lipase activities but 37% lower total pancreatic amylase activity than fall migrants, which suggests that the spring diet was enriched with lipids but low in glycogen. Spring migrants also had 47% higher total intestinal maltase activity as well as 56% higher standardized maltase and 13% higher standardized aminopeptidase-N activities. Spring migrants had higher total enzymic capacity than fall migrants, due primarily to higher total lipase and maltase activities. During fall migration, the juvenile's digestive system was 10% larger than the adult's, and it was composed differently: juveniles had a 16% larger small intestine but a 27% smaller proventriculus. The juvenile's larger digestive system was associated with lower total enzymic capacity than the adult's due to 20% lower total chitinase and 23% lower total lipase activities. These results suggest that juvenile western sandpipers may process food differently from adults and/or have a lower-quality diet.

Corn distiller's dried grains with solubles: Apparent digestibility and digestive enzymes activities in European seabass (Dicentrarchus labrax) and meagre (Argyrosomus regius)

The activity of the digestive enzymes lipase, α-amylase and disaccharidases (sucrase, maltase, isomaltase and trehalase) was studied in slow-growing and fast-growing groups of farmed Eurasian perch (Percafluviatilis) of different ages.The activity of carbohydrases (disaccharidases and α-amylase), lipase, trypsin and chymotrypsin were also compared in Eurasian perch andArcticcharr (Salvelinusalpinus).No effect was noted of growth rate and age on the digestive enzyme activities in Eurasian perch.Total lipase activity was higher than total combined carbohydrase activity in both species (142.0 vs. 6.2 and 111.0 vs. 2.5 Umg-1 protein for Eurasian perch and Arctic charr respectively; P<0.001 for both). Compared with Arctic charr, Eurasian perch had higher lipase activity in the pancreasand lower lipase activity in the pyloric caeca and mid-intestine. Total chymotrypsin activity was higher than total trypsin activity in both species, whereas total chymotrypsin activity was higher for Arcticcharr than for Eurasian perch (192.8 and 110.2 Umg sample-1 respectively; P<0.001). The high lipase and protease activity, and low carbohydrase activity in both species can be linked to their carnivorous feeding habits. Moreover, Eurasian Perch had a higher total carbohydrase activity than charr, suggesting a greater capacity for digesting carbohydrates, especially starch.

This study investigates the long-term effects of oral tea polyphenols (TPs) and Lactobacillus brevis M8 (LB) on biochemical parameters, digestive enzymes, and cytokines expression in broilers. In experiment 1, 240 broiler chickens were selected to investigate the effects of 0.06 g/kg body weight (BW) TP and 1.0 ml/kg BW LB on broilers; in experiment 2, 180 broiler chickens were assigned randomly to three groups to investigate the effects of different dosages of TP (0.03, 0.06, and 0.09 g/kg BW) combined with 1.0 ml/kg BW LB on broilers; in experiment 3, 180 broiler chickens were assigned randomly to three groups to investigate the effects of different dosages of LB (0.5, 1.0, and 1.5 ml/kg BW) combined with 0.06 g/kg BW TP on broilers. The results showed that TP and LB affected serum biochemical parameters, and TP reduced serum cholesterol (CHO) and low-density lipoprotein cholesterol (LDL-C) abundances in a dosage-dependent manner (P<0.05) on Day 84. Meanwhile, broilers fed a diet supplemented with TP or LB had a lower intestinal lipase activity on Day 84 compared with the control group (P<0.05). Middle and high dosages of TP increased pancreatic lipase and proventriculus pepsin activities (P<0.05). Also middle and high dosages of LB significantly enhanced pancreatic lipase activity (P<0.05), while high LB supplementation inhibited intestinal trypsase (P<0.05) on Day 84. Furthermore, both TP and LB reduced intestinal cytokine expression and nuclear factor-κ B (NF-κB) mRNA level on Days 56 and 84. In conclusion, long-term treatment of TP and LB improved lipid metabolism and digestive enzymes activities, and affected intestinal inflammatory status, which may be associated with the NF-κB signal.

Determining digestive enzyme activity is of potential interest to obtain and understand valuable information about fish digestive physiology, since digestion is an elementary process of fish metabolism. We described for the first time (i) three digestive enzymes: amylase, trypsin and intestinal alkaline phosphatase (IAP), and (ii) three gut morphometric parameters: relative gut length (RGL), relative gut mass (RGM) and Zihler’s index (ZI) in threespine stickleback (Gasterosteus aculeatus), and we studied the effect of temperature and body size on these parameters. When mimicking seasonal variation in temperature, body size had no effect on digestive enzyme activity. The highest levels of amylase and trypsin activity were observed at 18°C, while the highest IAP activity was recorded at 20°C. When sticklebacks were exposed to three constant temperatures (16, 18 and 21°C), a temporal effect correlated to fish growth was observed with inverse evolution patterns between amylase activity and the activities of trypsin and IAP. Temperature (in both experiments) had no effect on morphometric parameters. However, a temporal variation was recorded for both RGM (in the second experiment) and ZI (in both experiments), and the later was correlated to fish body mass.