Intestinal Digestive Enzyme Activities Research Articles

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

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

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

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

Effects of dietary glutamine dipeptide on growth performance, intestinal digestive enzyme activity, and gene expression of related factors in Penaeus vannamei

Effects of dietary glutamine dipeptide on growth performance, intestinal digestive enzyme activity, and gene expression of related factors in Penaeus vannamei

Effects of dietary short‐chain fatty acid salts on the growth performance, digestive, antioxidant and immune enzyme activities, immune‐related gene expression and resistance to Vibro parahaemolytics infection in juvenile ridgetail white prawn ( Exopalaemon carinicauda )

An 8-week feeding trial was conducted to study the effects of dietary short-chain fatty acid salts, sodium acetate (SA), sodium propionate (SP) and sodium butyrate (SB), on the growth performance, digestive ability, immune parameters and disease resistance of juvenile Exopalaemon carinicauda. Shrimps (14.60 ± 1.48 mg) were fed with 10 experimental diets containing 0.0 (control), 0.25%, 0.5% and 1% of SA, SB and SP in triplicate. The highest survival rate was observed in the SP (0.5%) group (p < 0.05). The final weight, specific growth rate and feed efficiency was highest in the SP (0.25%) group (p < 0.05). Shrimps that were fed SP (0.25%) had greater intestinal digestive enzyme (chymotrypsin) activity. Shrimps in the SA (0.5%) group had the highest activities of glutathione peroxidase, catalase, lysozyme, acid phosphatase and alkaline phosphatase, which was accompanied by the highest relative percent survival after a Vibro parahaemolyticus challenge (p < 0.05). The expression of immune-related genes (prophenoloxidase, C-type lectin and mannose binding lectin) in the hepatopancreas of shrimps fed SA (0.5%) and SP (0.25%) was higher than that of the control group (p < 0.05). These data suggest that SA (0.5%) and SP (0.25%) are beneficial to the growth performance and health of E. carinicauda.

Effects of fermented mulberry leaves on growth, serum antioxidant capacity, digestive enzyme activities and microbial compositions of the intestine in crucian ( Carassius carassius )

Mulberry (Morus alba) leaves are rich in proteins, vitamins and trace elements, which serve as ingredients of feed. However, the application of mulberry leaves is limited by the anti-nutritional factors present in them. In this study, we fermented the mulberry leaves using complex microorganisms containing lactic acid bacteria and yeast and investigated the effects of feed containing 0%, 5%, 10%, 15% and 20% FMLs on growth performance, serum antioxidant capacity, digestive capacity and intestinal microbiota composition in crucian (Carassius carassius). The intestinal microbiota composition was investigated using high-throughput sequencing of 16S rRNA gene. Our results showed that adding 5% FMLs to feed promoted growth performance, serum antioxidant capacity and intestinal digestive enzyme activities of crucian. There was no significant difference between the gut microbiota composition of crucian fed 5% FMLs and the blank control. When added FMLs exceeded 10%, the growth performance, serum antioxidant capacity and intestinal digestive enzyme activities decreased, and the homeostasis of gut microbiota was destroyed. These findings indicated that addition of 5% FMLs not only significantly promoted the growth of crucian, but also improved the antioxidant capacity and digestive capacity.

Effects of hypoxia stress on digestive enzyme activities, intestinal structure and the expression of tight junction proteins coding genes in juvenile cobia ( Rachycentron canadum )

In this study, juvenile cobia fish (Rachycentron canadum) (body weight: 50.44 ± 2.78 g) were used as a study object to investigate the effects of hypoxia stress (dissolved oxygen: 3.15 ± 0.21 mg/L) on the activities of their digestive enzymes, intestinal morphology and relative expression of tight junction proteins coding genes. Under the experimental conditions, the juvenile cobia were given 28 days of hypoxia stress. The results showed that the activities of digestive enzymes in the intestines of the hypoxia stress group decreased. In addition, the amylase and lipase activities decreased significantly (p < 0.05), and the trypsin activity in the hypoxia stress group compared to that in the control group. The morphology and structure of the intestine also showed significant changes. Under the microscopic observation, the mucosal fold height and muscle thickness of the intestine showed a significant decrease (p < 0.05); also, the villi's width showed a significant decrease (p < 0.05) in the hypoxia stress group as compared to that in the control group. The observation under a transmission electron microscope showed that the microvilli of juvenile cobia in the hypoxia stress group were irregularly arranged, atrophied and fallen off compared to the control group. Furthermore, there were gaps in the tight junction. In addition, the boundary between cells was unclear. The relative expression of intestinal tight junction proteins coding genes was down-regulated to varying degrees. The mRNA expressions of ZO-1 and claudin-4 were significantly down-regulated (p < 0.05) and ZO-2 and occludin in the hypoxia stress group compared to those in the control group. These results indicated that hypoxia stress could inhibit the activities of intestinal digestive enzymes, damage intestinal morphology and decrease the expression of tight junction proteins coding genes in cobia. The present study provided a scientific foundation for evaluating the multifaceted impacts of hypoxia stress on fish species, such as cobia.

Combined effect of Spirulina and ferrous fumarate on growth parameters, pigmentation, digestive enzyme activity, antioxidant enzyme activity and fatty acids composition of Yellow River carp (Cyprinus carpio)

This study was conducted to investigate the effects of Spirulina and ferrous fumarate supplementations into diets on growth parameters, pigmentation, digestive enzyme activity, antioxidant enzyme activity and fatty acids composition of Yellow River carp. Three experimental groups included control, Spirulina (diet 1), mixture of Spirulina and ferrous fumarate treatments (diet 2) in 3 replications in 9 aquariums. Fifteen fish in each aquarium were fed twice a day for six weeks. Compared to the control group, the Yellow River carp fed with the Spirulina and ferrous fumarate had a higher specific growth rate (P < 0.05). The total carotenoids content in Yellow River carp skin and scale was significantly higher for fish fed diet with Spirulina and ferrous fumarate relative to all other diets (P < 0.05). The color parameters of L *, a *, b*, Hue (Hab°) and Chroma (ch*) were calculated for all treatments. Obtain findings revealed that the Spirulina and ferrous fumarate treatment could provide the desired skin color exactly of Yellow River carp. The Spirulina and ferrous fumarate supplementation significantly elevated intestinal digestive capacity by increasing amylase, lipase, and trypsin enzyme activities (P < 0.05). The results obtained indicated that Spirulina and ferrous fumarate supplementation could improve intestinal health through enhancing intestinal digestive enzyme activity and reducing tissue peroxidation. In addition, the Spirulina and ferrous fumarate has a satisfactory nutritional value of improving the fatty acid profile. Therefore, the use of Spirulina and ferrous fumarate as feed additive could be practiced in the aquaculture species.

Effects of different levels of stevioside on growth performance, digestive enzyme activity, antioxidant capacity and gene expression of juvenile mirror carp (Cyprinus carpio)

The study evaluated the effects of different levels of stevioside (STE) on the growth performance, intestinal digestive enzyme activity, liver antioxidant indices, and gene expression of juvenile songpu mirror carp (Cyprinus carpio). The carp were fed with six diets supplemented with 0 (control), 80, 160, 240, 320, and 400 mg/kg of STE, respectively. 540 juvenile mirror carp with an average initial weight of 3.00 ± 0.15 g were randomly divided into 6 groups, 3 replicates in each group and 30 fish in every replicate. The carp were fed to satiation for 56 days. The results showed that the weight gain rate (WGR), the condition factor (CF), and the ash content were increased linearly (P < 0.05), but the hepatosomatic index (HSI) was decreased linearly (P < 0.05). Dietary STE supplementation tended to improve the total protein (TP), total cholesterol (TCHO), and low-density lipoprotein (LDL) content (P < 0.10). The activity of superoxide dismutase (SOD) was increased quadratically (P ≤ 0.05). The addition of STE tended to increase the activity of protease and decrease amylase activity in the foregut (P < 0.10). The expression of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and myeloid differentiation factor88 (MyD88) mRNA did not vary significantly (P > 0.05). It is confirmed from the study that the addition of STE could improve growth performance, liver antioxidant capacity, and immune function. Based on a broken-line regression analysis between the WGR and SOD activity against the dietary STE levels, the optimal dietary STE is 217.68 and 215.21 mg/kg, respectively.

Influences of dietary Eucommia ulmoides extract on growth, flesh quality, antioxidant capacity and collagen-related genes expression in grass carp (Ctenopharyngodon idellus)

The study investigated the effects of dietary Eucommia ulmoides extracts on growth, flesh quality and collagen-related genes expression of grass carp (Ctenopharyngodon idella). Eucommia ulmoides bark extract (EBE) and Eucommia ulmoides leaf extract (ELE) were individually supplemented into basal diet (control) at an inclusion of 4 g/kg, and then the three diets were fed to grass carp (59.7 ± 0.3 g) for 60 days. The results indicated that dietary ELE significantly increased weight gain (+4.22 %), and decreased feed conversion ratio (-4.05 %) (P < 0.05), while EBE did not significantly affect the growth performance of grass carp. Compared to the control, dietary ELE significantly increased apparent digestibility coefficient of dry matter, crude protein and intestinal digestive enzyme activity (P < 0.05), and the contents of calcium, total collagen, heat-insoluble collagen and free amino acids level (including delicious amino acids) in flesh were also significantly increased (P < 0.05). In both extracts groups, the flesh centrifugal loss, steaming loss, drip loss24h, protein carbonyl and malondialdehyde were significantly lower, and superoxide dismutase and glutathione peroxidase activities were significantly higher than the control (P < 0.05). No significant differences in the amount of saturated, monounsaturated and polyunsaturated fatty acids in flesh were found among the three groups, but docosapentaenoic acid (DPA), docosahexaenic acid (DHA), n-3 polyunsaturated fatty acids and n-3/n-6 ratio in flesh were significantly increased by dietary EBE and ELE (P < 0.05). In collagen-related genes expression, the ELE supplementation significantly promoted the expression of collagen type I (COL1A1, COL1A2), proline hydroxylase, lysine oxidasein in muscle, while the expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 was significantly decreased (P < 0.05). In conclusion, dietary ELE improved the growth, muscle antioxidant capacity and flesh quality of grass carp.

Effect of dietary coated granules containing garlic oil diallyl disulphide and diallyl trisulphide on performance, in vitro digestibility and gastrointestinal functionality in laying hens

This experiment was conducted to investigate the effects of dietary supplementation with coated granules (CG) on performance, in vitro digestibility and the gastrointestinal functionality in laying hens. A total of 40 Hisex Brown laying hens (36weeks of age) were randomly divided into five equal groups; one served as a control and the other four were actual experimental groups supplemented with 0.75, 1.5, 3 or 6g CG per day. All the hens were fed restrictively with target feed intake of 100g basal diet/hen per day. There were no differences in egg production or egg weight among the groups, but feed conversion ratio was significantly improved (linearly, p<0.05) with the dose level of CG in diet. Dietary CG increased the jejunal weight (linear and quadratic terms, p<0.05) but decreased the ileal weight (linearly, p<0.05). There was mostly statistical interaction between dietary CG and specific activity of intestinal digestive enzymes with similar patterns for dietary CG treatments (p<0.05). A positive linear correlation was observed with in vitro protein digestibility by using the crude enzyme extract from dietary CG supplementation. Dietary CG decreased the caecal Escherichia coli population while the Lactobacillus spp.: E.coli ratio increased (quadratic fit, p<0.05). CG supplementation, on the other hand, significantly altered intestinal morphology by increasing the height of duodenal and ileal villi (linearly, p<0.05). Also, duodenal antioxidant capacity observed via remaining reducing power improved linearly (p<0.05). This suggests that CG, unlike garlic oils without encapsulation, may be a good candidate for feed supplementation in commercial egg production. It could be included up to 6g CG per day without any adverse effects on performance, which may relate to improving nutrient digestibility and better utilization of limited feed intake when using a low amount of diet or other observations in this study.

Screening of intestinal probiotics and the effects of feeding probiotics on the digestive enzyme activity, immune, intestinal flora and WSSV resistance of Procambarus clarkii

In this experiment, a potential probiotic strain A23 with high antimicrobial activity against common aquatic pathogens and extracellular enzyme production was isolated from the intestine of healthy Procambarus clarkii. Biochemical and 16S rDNA sequencing analysis identified A23 as Bacillus amyloliquefaciens, and a haemolytic test and antibiotic susceptibility test were carried out on strain A23 to determine its safety. First, the whole genome of B. amyloliquefaciens A23 was determined to explore its mechanism of action. The results showed that the total length of the genome was 3,974,398 bp, the GC content was 46.56%, and 3843 genes were encoded, including 27 rRNA operons and 86 transfer RNA genes. Three bacilysin-related genes and 10 antimicrobial peptide (AMP)-related genes were found through manual inspection. Second, we evaluated the beneficial effects of strain A23 in P. clarkii by performing in vivo feeding experiments. The results showed that probiotic supplementation could effectively enhance the intestinal digestive enzyme activities, innate immune enzyme activities and white spot syndrome virus (WSSV) resistance of P. clarkii. Finally, the intestinal microbial community and diversity of crayfish were compared and analyzed by high-throughput sequencing. At the phylum level, the abundance of Proteobacteria decreased with 108 CFU/g probiotics supplement, while the abundance of Firmicutes and Bacteroides increased. The Shannon index of the intestinal microorganism community of the 108 CFU/g probiotic supplementation group was significantly higher than that of the control group, indicateding that 108 CFU/g probiotic supplementation enhanced intestinal microbial diversity. The results from this study demonstrated that B. amyloliquefaciens A23 is a promising probiotic candidate that provides multiple benefits for crayfish cultivation.

Co-bedding of Preterm Newborn Pigs Reduces Necrotizing Enterocolitis Incidence Independent of Vital Functions and Cortisol Levels.

Background: Preterm infants are born with immature organs, leading to morbidities such as necrotizing enterocolitis (NEC), a gut inflammatory disease associated with adverse feeding responses but also hemodynamic and respiratory instability. Skin-to-skin contact including “kangaroo care” may improve infant survival and health via improved vital functions (e.g., pulmonary, cardiovascular) and endocrine influences by adrenal glucocorticoids. Clinical effects of skin-to-skin contact for newborn siblings (“co-bedding”) are not known. Using NEC-susceptible Preterm pigs as models, we hypothesized that co-bedding and exogenous glucocorticoids improve vital functions and NEC resistance.Methods: In experiment 1, cesarean-delivered, formula-fed Preterm pigs were reared in incubators with (co-bedding, COB, n = 30) or without (single-bedding, SIN, n = 29) a sibling until euthanasia and tissue collection on day four. In experiment 2, single-bedded Preterm pigs were treated postnatally with a tapering dose of hydrocortisone (HC, n = 19, 1–3 mg/kg/d) or saline (CON, n = 19).Results: Co-bedding reduced NEC incidence (38 vs. 65%, p < 0.05) and increased the density of colonic goblet cells (+20%, p < 0.05) but had no effect on pulmonary and cardiovascular functions (respiration, blood pressure, heart rate, blood gases) or cortisol levels. There were limited differences in intestinal villous architecture and digestive enzyme activities. In experiment 2, HC treatment increased NEC lesions in the small intestine without any effects on pulmonary or cardiovascular functions.Conclusion: Co-bedding may improve gut function and NEC resistance independently of cardiorespiratory function and cortisol levels, but pharmacological cortisol treatment predispose to NEC. Preterm pigs may be a useful tool to better understand the physiological effects of co-bedding, neonatal stressors and their possible interactions with morbidities in Preterm neonates.

Evaluation of defatted Hermetia illucens larvae meal for Litopenaeus vannamei : effects on growth performance, nutrition retention, antioxidant and immune response, digestive enzyme activity and hepatic morphology

Defatted black soldier fly (Hermetia illucens) larvae meal (DBSFLM) has been shown an important alternative protein ingredient for fish, but little information is available about the effect of DBSFLM on growth and health of Litopenaeus vannamei. A 56-day feeding trial was conducted to assess the effects of partial replacement of fish meal with DBSFLM on growth performance, body composition, nutrition retention, blood metabolites, antioxidant and immune response, digestive enzyme activities and hepatic morphology of L. vannamei. Six isonitrogenous and isoenergy diets were formulated by replacing 0% (G0), 15% (G15), 30% (G30), 45% (G45), 60% (G60) and 80% (G80) of fish meal with DBSFLM. Each diet was randomly assigned to quadruplicate groups of 40 shrimp per tank. Shrimp were fed three times daily to apparent satiation. Blood samples were collected at the terminal trial to analyse antioxidant and non-specific immune enzyme activities. Hepatopancreas and intestine samples were collected to determine digestive enzyme activities and hepatic morphology. Shrimp fed G80 had lower (p < .05) final body weight, weight gain and specific growth rate, and higher (p < .05) feed conversion ratio than other groups. Crude protein (CP) in the whole body and muscle, coupled with CP and lipid retention of shrimp were decreased (p < .05) as dietary DBSFLM increasing. Shrimp fed G80 had lower (p < .05) serum total cholesterol but higher (p < .05) total antioxidant capacity than other diets, and serum malondialdehyde was lower (p < .05) in shrimp fed G45-G80 than those fed G0-G30. Hepatic and intestinal digestive enzyme activities were not altered by treatments (p > .05). Hepatocytes were shown to have different degrees of vacuolar degeneration, hepatic corpuscle atrophy and starlike lumen lose as observed in G60 and G80. The results demonstrated that up to 60% of fish meal could be replaced by DBSFLM without any adverse effects on growth performance, antioxidant and immune enzyme activities, and digestive enzyme activities of L. vannamei. However, hepatocyte damage was observed when the replacement levels exceeded 60%.

Effects of dietary florfenicol contained feeds on growth and immunity of European seabass (Dicentrarchus labrax) in flow-through and recirculating aquaculture system

Antibiotic growth promoters have been banned in animal husbandry and aquaculture in China, since 2020. Florfenicol (FLO) is the most used antibiotics in aquaculture for controlling various bacterial disease in fish, although its effect on health of farmed fish remains a concern. In the present study, European seabass (Dicentrarchus labrax) reared under flow-through aquaculture system (FAS) and recirculating aquaculture system (RAS), were fed on diets supplemented with FLO for 10 d, followed by a 20-d withdrawal period. The effects of FLO on the growth performance, intestinal digestive enzyme activities, serum biochemical parameters, antioxidant enzymes, and expression of related genes, were evaluated. The results showed that FLO exposure inhibited growth performance of D. labrax although this was recovered after stopping the feeding. Besides, FLO suppressed α-Amylase and trypsin activities in the intestine, and the amounts of nutrition-related indicators were also affected. In addition, FLO exposure upregulated liver cellular damage markers (ALT, ALP, and AST) during the treatment phase, although it did not pose a high potential for liver damage. We also observed elevated levels of SOD, CAT, and MDA in gills, indicative of oxidative stress on the cultured fish. Moreover, integrated biomarker response results indicated that fish in RAS had higher growth performance and immunity in the late post-treatment phase, relative to those in RAS, after FLO exposure. This was attributed to high-efficient water treatment of RAS. Overall, these results indicate that exposure to FLO modulates digestive enzyme activities and antioxidant response in European seabass, thereby affecting their growth performance and immune response under different aquaculture modes.

Dietary glycerol inclusion decreases growth performance and nitrogen retention efficiency in rainbow trout (Oncorhynchus mykiss)

Glycerol is an inexpensive source of dietary energy, although its inclusion in compound feeds has been barely investigated in fish. The effects of dietary refined glycerol inclusion on growth performance, nitrogen and energy balance, as well as its digestibility and intestinal digestive enzyme activities was studied in rainbow trout. Fish (initial BW 20.2 ± 0.1 g, mean ± SE) were divided into nine tanks (1.66 kg m−3), each one assigned to the experimental diets, in triplicates. Fish were fed twice a day to apparent satiation for 60 days three diets including 0, 25, or 50 g kg−1 of refined glycerol (G0, G25, and G50, respectively) with similar digestible protein to energy ratios (22 mg kJ−1). A digestibility trial was conducted in parallel to the growth trial by using a Choubert System to collect feces, in triplicates. Refined glycerol was well digested (ADCglycerol > 99.7%) when included up to 50 g kg−1. Specific growth rate (SGR) decreased as glycerol inclusion levels increased in the diet (P = 0.029). Feed intake was enhanced with increasing dietary inclusion levels of glycerol (P = 0.013). The feed efficiency decreased linearly as the glycerol inclusion levels increased in the diet, reflected in a higher FCR ratio, particularly in the G50 group compared to the G0 or G25 groups (1.04 ± 0.02, 0.90 ± 0.02 and 0.91 ± 0.02, respectively). Total ammonia nitrogen excretion rate (TANER) was measured in trout at the end of the growth trial, displaying increased values with higher dietary glycerol inclusion levels (P < 0.001). As a result, trout fed G25 or G50 diets displayed an increased energy intake, which was not reflected in a reduction of the nitrogen excretion rate. Contrary to expected, glycerol had a negative effect on nitrogen efficiency, indicating that dietary inclusion of this compound does not spare the use of proteins as a metabolic fuel. In addition, amylase, but not proteases and lipase, was altered in the intestine of trout by refined glycerol inclusion, as this digestive enzyme activity increased 6 h post-feeding in trout fed G25 and G50 diets. In conclusion, dietary refined glycerol inclusion on rainbow trout was not reflected in beneficial effects on fish performance or in the quantity of nitrogen waste products excreted to the environment by this carnivorous species.

Feeding sundried cassava leaf meal as a replacement for de‐oiled rice bran in the diets of rohu, L abeo rohita , fingerlings: effect on growth, enzyme activities and gene expression of igf‐i and igf‐bpi

A 75-day feeding trial was conducted to evaluate the nutritional implication of feeding diets containing graded levels of sundried cassava leaf meal (SCLM) to Labeo rohita fingerlings. Four isonitrogenous (300 g/kg crude protein) and isoenergetic (18 MJ/kg) diets were prepared by replacing de-oiled rice bran (DORB) with 0 (diet 1), 130 (diet 2), 260 (diet 3) and 390 g/kg (diet 4) of SCLM. The diets were fed to the triplicate groups of L. rohita fingerlings (average weight, 2.03 ± 0.03 g) in a completely randomized experimental design. At the end of the trial, diet 3 had similar (p > 0.05) percentage weight gain (106.38 ± 4.41%), specific growth rate (1.29 ± 0.04%/day) and feed conversion ratio (2.38 ± 0.08) relative to the control group. Intestinal digestive enzyme activities, hepatic and muscle transaminases and proximate body composition of L. rohita fingerlings were not significantly (p > 0.05) influenced by the dietary treatment. Superoxide dismutase activity of the group reared on diets 3 and 4 was significantly (p < 0.05) higher than that of diet 1. Based on the second-order polynomial regression analysis on the expression of IGF-I and IGF-BPI, it was concluded that as much as 166.5 g/kg DORB can be replaced by SCLM for optimal growth performance, in the diets of L. rohita fingerlings.

High protein intake promotes the adaptation to chronic hypoxia in zebrafish (Danio rerio)

Chronic hypoxia is a common environmental stress factor in aquaculture. Many researchers have illustrated the physiological and metabolic changes under chronic hypoxia, but there are few studies to evaluate the relationship between dietary nutrients and hypoxic adaptation in fish. In the present study, we fed zebrafish with control diet (C), high-carbohydrate diet (HC), high-fat diet (HF) and high-protein diet (HP) at normal dissolved oxygen (DO = 7.0 ± 0.5 mg/L) or low dissolved oxygen (DO = 2.5 ± 0.5 mg/L) environment, respectively. After a 7-week feeding trial, the growth performance, body composition, tissue biochemical indexes, mRNA expressions of hifα isoforms and nutrient metabolism-related genes, intestinal digestive enzyme activities and microbiota composition were measured. The results indicated that only the HP diet could alleviate the reduction of body weight and feed efficiency induced by chronic hypoxia, but the HF diet feeding worsened the adverse effects of chronic hypoxia in zebrafish. At the C groups, hypoxia increased catabolism of lipid and protein, but at the HP groups, hypoxia enhanced utilization of glycogen and protein. Compared to the C-hypoxia group, the HP feeding could activate transcription of hif-1a and its downstream glycolysis genes in chronic hypoxia. Furthermore, at hypoxic state, the HP feeding could alleviate the reduction of intestinal digestive enzyme activities and microbiota dysbiosis induced by the chronic hypoxia, including increasing bacterial diversity and decreasing Cetobacterium genus abundance. This is the first study indicating that high protein intake could strengthen ability of fish in resisting the negative effect of chronic hypoxia.

243 Ileal Terminal Starch Hydrolytic Activity Is Increased in Association with Improved Growth and Feed Efficiency in Weaning Pigs Fed a Therapeutic Multi-antimicrobial-supplemented Diet

Abstract Understanding roles of prescribed in-feed therapeutic multi-antimicrobials in affecting the small intestinal terminal starch digestive enzyme activity in improving weaning pig growth and feed utilization may shed light on developing novel alternative strategies to reduce uses of antimicrobials. A total of 125 crossbred barrows, weaned on d 19–21 with an average initial BW of 6.9 ± 0.1 kg, were randomly assigned to two corn, SBM and dried whey powder based diets for 21 d according to a randomized complete block design. The multi-antimicrobial diet was supplemented with aureomycin 220, tiamulin 31.2 and ZnO 2,358 at mg/kg diet. The growth performances including final BW (control, 13.9 ± 0.2 vs. antimicrobials, 15.0 ± 0.2 kg), ADG (control, 0.307 ± 0.009 vs. antimicrobials, 0.355 ± 0.009 kg/d), ADFI (control, 0.425 ± 0.012 vs. antimicrobials, 0.455 ± 0.013 kg/d) and F:G (control, 1.39 ± 0.03 vs. antimicrobials, 1.28 ± 0.03 kg/kg) were improved (P &amp;lt; 0.05; n = 25 pens; 5 barrows/pen) compared to the non-antimicrobial control diet. The combined enzyme kinetics of the jejunal and the ileal maltase-glucoamylase (MGA) and sucrase-isomaltase (SI) activity were determined with the jejunal and the ileal homogenates by using maltose (0–60 mM in incubation mixture). The combined jejunal and the ileal MGA-SI affinity Km values and the combined jejunal MGA-SI maximal activity Vmax values were not different (P &amp;gt; 0.05) between the two diet groups. However, the combined ileal MGA-SI Vmax (nmol·mg protein-1·min-1) was increased in the antimicrobial diet (P &amp;lt; 0.05; control, 125.6 ± 10.84, n = 13 pigs vs. antimicrobials, 170.8 ± 12.15, n = 11 pigs) in comparison with the control diet. The Pearson’s correlation analyses revealed that the combined ileal MGA-IS Vmax of hydrolyzing maltose was associated with ADG (P = 0.0669; r = 0.38; n = 24 pigs) and feed efficiency (F:G; P &amp;lt; 0.05; r = -0.53; n = 24 pigs). Our results suggest that in-feed therapeutic multi-antimicrobials could improve the distal small intestinal terminal starch digestive enzyme MGA-SI activity, thus improving growth and feed efficiency in weaning pigs.

219 Effects of maternal nutrient restriction and rumen-protected arginine supplementation on post-ruminal digestive enzyme activities of lamb offspring

Abstract To determine the effects of maternal nutrient restriction and rumen-protected arginine supplementation on post-ruminal digestive enzymes in lambs, 31 multiparous, Rambouillet ewes were allocated to one of three dietary treatments at 54 d of gestation. Dietary treatments were 100% of nutrient requirements (control, CON; n=11), 60% of control (restricted, RES; n=10), or RES plus a rumen-protected arginine supplement dosed at 180 mg/kg BW once daily (RES-ARG; n=10). At parturition, lambs were immediately removed from dams and reared independently. Milk-replacer and alfalfa hay + creep feed was offered for ad libitum intake. At day 54 of age, lambs were slaughtered and the pancreas and small intestine were collected. Pancreatic (α-amylase, trypsin) and small intestinal (maltase, glucoamylase, sucrase, isomaltase, lactase) digestive enzyme activities were assayed. Data were analyzed using the GLM procedure of SAS with treatment and fetal sex included in the model statement. Contrast statements were used to determine differences between means for effects of restriction (CON vs. RES and RES-ARG) and rumen-protected arginine supplementation (RES vs. RES-ARG). There was no influence (P≥0.32) of maternal nutrient restriction or rumen-protected arginine supplementation on pancreatic or small intestinal protein concentrations. No treatment effects were observed (P≥0.14) for enzymes involved in starch digestion including pancreatic α-amylase and small intestinal maltase, glucoamylase, and isomaltase. Sucrase activity was undetected in the small intestine of lambs across all treatments. Maternal nutrient restriction tended to increase (P=0.09) pancreatic trypsin specific activity in lambs. Lactase specific activity in the small intestine of lambs tended to decrease (P=0.08) with maternal nutrient restriction. Rumen-protected arginine supplementation to gestating ewes did not influence (P≥0.19) digestive enzyme activities of lamb offspring. These data suggest that maternal nutrient restriction may result in increased pancreatic trypsin activity of lambs to potentially compensate for inadequate pre-natal nutrient supply.

PSIX-7 Grazing toxic endophyte-infected tall fescue does not influence pancreatic or small intestinal digestive enzyme activities in beef steers

Abstract The objective of this experiment was to determine the influence of toxic endophyte-infected tall fescue exposure on pancreatic and small intestinal digestive enzyme activities in steers. Twelve fescue-naive beef steers [693 ± 42.7 kg of body weight (BW)] were stratified by BW and randomly assigned within BW ranks to graze non-toxic endophyte-infected tall fescue (NTE, n = 6; 0.01 ± 0.009 mg ergovaline + ergovalinine/kg) or toxic endophyte-infected tall fescue (TE, n = 6; 0.50 ± 0.048 mg ergovaline + ergovalinine/kg) pastures for 84 d. After the grazing period, steers were weighed and then slaughtered in three groups for tissue collection. A 1-m segment of the small intestine was collected 5-m distal to the pyloric sphincter. Subsamples of the small intestinal mucosa and pancreas were collected, homogenized in saline, and assayed for protein concentration. Pancreatic and small intestinal digestive enzyme activities were assayed. Data were analyzed using the GLM procedure of SAS as a randomized complete block design for effects of treatment and slaughter group (blocking factor). Steers grazing NTE pastures had a greater (P &amp;lt; 0.001) average daily gain (0.282 vs -0.631 kg/d) and final BW at slaughter (739 vs 620 kg) than steers grazing TE pastures. Small intestinal segment mass and mucosal density (P ≥ 0.16) were not influenced by treatment. Grazing TE pasture did not influence (P ≥ 0.21) pancreatic or small intestinal protein concentrations. Pancreatic α-amylase and trypsin activity per gram pancreas (P ≥ 0.21) or per gram pancreatic protein (P ≥ 0.30) were not influenced by fescue treatment. Small intestinal glucoamylase, isomaltase, and maltase activities did not differ between steers grazing NTE or TE pastures when expressed per gram of intestinal tissue (P ≥ 0.47) or per gram of intestinal protein (P ≥ 0.60). These data indicate that decreased gains observed in cattle consuming TE are not a result of decreased pancreatic or small intestinal digestive enzyme activities.