The effects of xylanase supplementation on growth, digestion, circulating hormone and metabolite levels, immunity and gut microflora in cockerels fed on wheat-based diets

Multi-copy expression of a protease-resistant xylanase with high xylan degradation ability and its application in broilers fed wheat-based diets

The acidic thermostable xylanase (AT-xynA) has great potential in the feed industry, but its low activity is not conductive to large-scale production, and its application in poultry diets still needs to be further evaluated. In Experiment1, AT-xynA activity increased 3.10 times by constructing multi-copy strains, and the highest activity reached 10,018.29 ± 91.18 U/mL. AT-xynA showed protease resistance, high specificity for xylan substrates, xylobiose and xylotriose were the main hydrolysates. In Experiment2, 192 broilers were assigned into 3 treatments including a wheat-based diet, and the diets supplemented with AT-xynA during the entire period (XY-42) or exclusively during the early stage (XY-21). AT-xynA improved growth performance, while the performance of XY-21 and XY-42 was identical. To further clarify the mechanism underlying the particular effectiveness of AT-xynA during the early stage, 128 broilers were allotted into 2 treatments including a wheat-based diet and the diet supplemented with AT-xynA for 42 d in Experiment3. AT-xynA improved intestinal digestive function and microbiota composition, the benefits were stronger in younger broilers than older ones. Overall, the activity of AT-xynA exhibiting protease resistance and high xylan degradation ability increased by constructing multi-copy strains, and AT-xynA was particularly effective in improving broiler performance during the early stage.

Effect of endo-1,4-beta-xylanase supplementation to low-energy diets on performance, blood constituents, nutrient digestibility, and gene expressions related growth of broiler chickens

The presence of soluble and insoluble non-starch polysaccharides (NSP) was reported to reduce nutrient utilisation, and adversely impact the broilers' growth performance; accordingly, NSP-degrading enzymes are essential supplements to cereal-based diets. Therefore, the current trial was conducted to characterise the impacts of supplemental xylanase (Xyl) to diets with low-ME levels on performance, carcass traits, blood parameters, nutrient digestibility and some genes expressions in broiler chickens. A total of 600 1-day-old Ross 308 male broiler chicks were randomly assigned to 6 treatments with 10 replications of 10 birds each per group in a completely randomised design. The 6 treatments were as follow: (1) basal diets with balanced ME content served as control (positive control, PC), (2) low-energy diet (negative control 1 [NC1]; ME content reduced by 70 kcal/kg compared with PC), (3) low-energy diet (negative control 2 [NC2]; ME content reduced by 140 kcal/kg compared with PC), (4) NC1 + 100 g/ton xylanase (NC1 + 100Xyl), (5) NC2 + 100 g/ton xylanase (NC2 + 100Xyl), and (6) NC1 + 50 g/ton xylanase (NC1 + 50Xyl). At the end of the experiment (35 days of age), the reduction of energy in the NC diets yielded lower live body weight (BW) and total body weight gain (BWG) (p ˂ 0.001); however, it significantly increased feed intake (p ˂ 0.05), leading to worst feed conversion ratio (FCR) and European production efficiency factor (EPEF) (p ˂ 0.01) than PC. There was non-significant variation in final BW, BWG, FCR, or EPEF between the PC group and the NC groups supplemented with Xyl. Carcass yield, gizzard, liver and, muscle relative weights were not influenced by dietary treatments; while broilers fed diet with low-energy diets with or without Xyl addition had lower abdominal fat (p ˂ 0.01) than PC. Furthermore, broilers fed on low-ME diets supplemented with Xyl showed a reduction in plasma total cholesterol (p ˂ 0.05) and low density lipoprotein (p ˂ 0.01) levels. Greater antibody titre against Newcastle disease (p ˂ 0.05) was recorded in the NC1 + 100Xyl and NC2 + 100Xyl groups. The addition of Xyl to low-energy diets significantly improved (p ˂ 0.05) fibre digestibility compared to the PC group. Moreover, enzyme supplementation increased muscle total lipids content and decreased muscle thiobarbituric acid retroactive substance content. In addition, enzyme supplementation increased gene expression related to growth and gene expression related to fatty acid synthesis. It was concluded that a low-ME diet might diminish broiler performance, whereas Xyl supplementation to low-ME diets beneficially affected growth performance, abdominal fat percentage, nutrient digestibility and immunity for broilers, and gene expressions related to growth and fatty acid synthesis in broiler chickens fed low-energy diets.

Hematology profile, digestive enzymes, thyroid hormones, productivity, and nitrogen balance of growing male rabbits supplemented with exogenous dietary lysozyme

In a simple randomized design trial, 420 growing male V-Line rabbits were randomly distributed into four groups to investigate the impact of exogenous dietary lysozyme on some physiological and nutritional parameters of male growing rabbits supplemented with exogenous dietary lysozyme. The witness group received a basal diet without exogenous dietary lysozyme (LYZ0), while the exogenous dietary lysozyme groups received 50, 100 and 150 mg/kg of basal diet (Groups; LYZ50, LYZ100 and LYZ150), respectively. The results showed significantly increased in blood cell count, hemoglobin concentration, total white blood cell, lipase, protease, amylase, total protein, triiodothyronine and thyroxine levels, while thyroid stimulating hormone levels significantly lessened in rabbits received LYZ. The LYZ- rabbit diets improved total digestible nutrient, digestible crude protein, and digestible energy values, with the LYZ100 group outperforming the others. LYZ-treated rabbits had significantly higher nitrogen intake, digestible nitrogen, and nitrogen balance than the witness group. The lysozyme in a rabbit's diet is taking on a new role as a digestive enzyme, enhancement thyroid hormones, as well as improvement hematology, daily protein efficiency ratio, daily performance index, hot carcass, total edible parts, nutritional value, and nitrogen balance, with decreasing the daily caloric conversion ratio and total non-edible parts.

Effects of adaptation diet and exogenous enzymes on true metabolizable energy and cecal microbial ecology, short-chain fatty acid profile, and enzyme activity in roosters fed barley and rye diets

Three experiments evaluated effects of adaptation diet and exogenous β-glucanase and xylanase on TME_n of barley and rye. Single Comb White Leghorn roosters were fed adaptation diets based on corn/soybean meal (SBM), barley/SBM with and without β-glucanase, or rye/corn/SBM with and without xylanase for 4 wk. In Experiments 1 and 2, after the adaptation period, TME_n was determined using a 48 h precision-fed rooster assay for 100% barley or 100% rye diets with or without β-glucanase or xylanase, respectively. Experiment 3 consisted only of feeding adaptation diets for 4 wk. Cecal samples were collected at the end of experiments for microbial ecology, short-chain fatty acid (SCFA) profiles, and enzyme activity analyses. In Experiments 1 and 2, β-glucanase increased (P < 0.05) TME_n of barley, and there was no significant effect of adaptation diet on TME_n values. Total cecal Eubacteria and Ruminococcaceae were decreased (P < 0.05) and Escherichia coli were increased (P < 0.05) at the end of the TME_n assay compared with the end of the adaptation period (with no TME_n assay). There was a large decrease (P < 0.05) for most cecal SCFA at the end of the TME_n assay compared with the end of the adaptation period. Both cecal β-glucanase and xylanase activity were increased for birds fed adaptation diets containing the respective enzyme. In Experiment 3, there were no consistent effects of adaptation diet on cecal microbial profiles or SCFA but cecal β-glucanase activity was increased (P < 0.05) by exogenous β-glucanase for barley and cecal xylanase activity was increased (P < 0.05) by exogenous xylanase for rye. Overall, the results indicated that TME_n of barley was increased by exogenous β-glucanase, adaptation diet did not significantly influence the TME_n response to the dietary enzymes, and cecal fermentation (based on cecal SCFA) was greatly reduced by the TME_n assay. Cecal β-glucanase and xylanase activity, however, were often increased by feeding high barley and high rye diets containing exogenous enzymes.

Molecular insight into cellulose degradation by the phototrophic green alga Scenedesmus

Lignocellulose is the most abundant natural biopolymer on earth and a potential raw material for the production of fuels and chemicals. However, only some organisms such as bacteria and fungi produce enzymes that metabolize this polymer. In this work we have demonstrated the presence of cellulolytic activity in the supernatant of Scenedesmus quadricauda cultures and we identified the presence of extracellular cellulases in the genome of five Scenedesmus species. Scenedesmus is a green alga which grows in both freshwater and saltwater regions as well as in soils, showing highly flexible metabolic properties. Sequence comparison of the different identified cellulases with hydrolytic enzymes from other organisms using multisequence alignments and phylogenetic trees showed that these proteins belong to the families of glycosyl hydrolases 1, 5, 9, and 10. In addition, most of the Scenedesmus cellulases showed greater sequence similarity with those from invertebrates, fungi, bacteria, and other microalgae than with the plant homologs. Furthermore, the data obtained from the three dimensional structure showed that both, their global structure and the main amino acid residues involved in catalysis and substrate binding are well conserved. Based on our results, we propose that different species of Scenedesmus could act as biocatalysts for the hydrolysis of cellulosic biomass produced from sunlight.

Changes in Growth Performance and Ileal Microbiota Composition by Xylanase Supplementation in Broilers Fed Wheat-Based Diets

Xylanase exerts key roles in improving growth performance and intestinal health of broilers fed wheat-based diets. However, knowledge is limited regarding effects of xylanase supplementation on ileal microbiota in broilers. A total of 128 one-day-old broilers (initial BW 48.03 ± 0.33 g) were selected to investigate effects of xylanase (AT-xynA) on growth performance, ileal morphology, microbiota composition, immune response, antioxidant capacity, and endocrine peptide levels in broilers. Broilers were randomly allotted into two dietary treatments (n = 8), namely, a wheat-soybean basal diet and a basal diet with 4,000 U/kg AT-xynA (XY). On days 7, 14, 21, and 42, broilers were weighted and ileal tissues were sampled. Ileal digesta samples were collected for analyzing microbiota composition on days 21 and 42. The results showed that AT-xynA could improve average daily weight gain and average daily feed intake, and there were interactions between diet and age of broilers (p < 0.05). On days 21 and 42, xylanase supplementation decreased ileal microbiota α-diversity, and the relative abundance of potentially pathogenic microbiota, such as phylum Proteobacteria, family Moraxellaceae and Staphylococcaceae, genus Staphylococcus, Pseudomonas, Streptococcus, and Enterococcus, increased the abundance of Lactobacillus (p < 0.05). Moreover, the reduction in acetate concentration and abundance of short-chain fatty acid-producing bacteria was also observed in broilers from XY group (p < 0.05). AT-xynA increased ileal villus height, glucagon-like peptide-1, and insulin-like growth factor-1 concentrations and decreased interleukin-1β, interleukin-6, tumor necrosis factor-α, and malondialdehyde content in broilers, and these positive effects on intestinal health were greater in young broilers. In conclusion, xylanase supplementation to wheat-based diets could improve ileal intestinal morphology and immune function, and alleviate excess fermentation of bacteria, which may be related to changes of intestinal microbiota. In addition, the positive effects of xylanase on intestinal health were more pronounced in young broilers, thus contributing to subsequent improvement in growth performance of broilers.

Dietary probiotics as a strategy for improving growth performance, intestinal efficacy, immunity, and antioxidant capacity of white Pekin ducks fed with different levels of CP

The potential impacts of probiotics on the performance and health status of white Pekin ducks fed with optimal or suboptimal dietary CP were evaluated during the growing period. A total of 180 male white Pekin ducks (14-day-old ducks with an initial weight of 415.65 ± 2.20 g) were randomly divided into 4 experimental groups (45 in each group of 5 replicates) in a 2 × 2 factorial design. The main factors included 2 dietary CP levels (18 or 14%) and dietary probiotic addition (with or without probiotics). The probiotic source was supplemented at 0.2 g per kilogram of diet from a blend of Lactobacillus acidophilus and Lactobacillus casei. The results showed that the diet containing 18% CP and probiotics significantly increases the final and total weight gain. Activities of intestinal enzymes (amylase, lipase, and protease), morphometrics (villus length, goblet cell count, and cryptal depth), and carcass percentage were also increased significantly. Total protein content, lysozyme activity, bactericidal activity, nitro blue tetrazolium levels, alternative complement pathway, superoxide dismutase activity, and catalase activity were significantly increased, whereas glucose, cortisol, and total cholesterol levels were decreased when treated with diet containing 18% CP and probiotics. Conversely, the group treated with diet containing 14% CP without probiotics showed the poorest performance, carcass properties, immune response, and antioxidant potential. In conclusion, probiotic addition to the 14% CP diet improved the performance of white Pekin ducks caused by reduced CP diet to performance due to the 18% CP diet without probiotic supplementation.

Effect of Different Levels of Multienzymes on Immune Response, Blood Hematology and Biochemistry, Antioxidants Status and Organs Histology of Broiler Chicks Fed Standard and Low-Density Diets

This study was executed to investigate the effect of supplementing three multienzyme levels (0, 0. 1, and 0.2%) with two types of diet [standard diet (SD) vs. low-density diet (LDD)] on immune response, blood hematology and biochemistry, antioxidant status, and organ histology of broilers during 1–38 days of age. A total of 216 unsexed 1-day-old Arbor Acres broiler chicks were randomly distributed, on a factorial design (2 × 3), to six treatments each with six replicates. There were six chicks per replicate. Results showed that LDD significantly decreased body weight gain (BWG) of broilers, but did not affect the European Production Efficiency Index (EPEI). Addition of multienzymes at both levels (0.1 and 0.2%) significantly increased BWG and improved EPEI, compared to the control diet. Alanine aminotransferase (ALT), aspirate aminotransferase (AST), malondialdehyde (MDA), lymphocyte, lymphocyte transformation test (LTT), and phagocyte activity (PA) were significantly higher for LDD than the SD, but eosinophil was lower. Supplementation of multienzymes significantly decreased ALT, AST, and MDA, compared to the control group, but increased packed cell volume (PCV), hemoglobin (Hgb), lymphocytes, and monocytes. Immune organs, such as spleen, thymus, and the bursa of Fabricius were significantly increased with multienzyme supplementation. It could be concluded that multienzyme supplementation at either 0.1 or 0.2% to SD or LDD improved EPEI and immune status of broiler chicks.

Influence of poly-enzyme preparation “Universal” on the meat productivity of Cherry-Valley ducks

Antibiotics widely used in poultry farms can have a harmful effect on meat consumers through chemical residues. Thus, it is important for the safety of customers to find a natural alternative. The purpose of this study was to evaluate the effectiveness of adding a poly-enzyme preparation “Universal”, containing amylosubtilin (1300 U/g), protosubtilin (67 U/g) and celloviridine (2000 U/g), on the productivity of broiler ducklings of the Cherry Valley breed. The results of research have shown that the addition of the “Universal” drug in the diet helped increase the meat productivity of broiler ducks. The use of the “Universal” drug contributed to the better development of internal organs (heart, liver and stomach) in broiler ducks. The improvement in duck weight and meat yield may be attributed to the fact that the feed protein is best consumed under the influence of protosubtilin, one of the “Universal.” It is understood that protosubtilin supplies digestible peptides and amino acids with hydrolysis of plant proteins from grain raw materials, enhances the gastrointestinal tract’s enzymatic history, compensates for the loss of depleted digestive enzymes and at the early stages of animal growth. Thus, the results of the experiment showed that the use of the drug “Universal” in the cultivation of broiler ducks of the cherry valley breed increases the pre-slaughter and slaughter weight, meat yield and reduces feed conversion, which is economically profitable. Therefore, it is recommended to use the drug “universal” as part of ration for broiler ducklings.

Xylanase and xylo- oligosaccharide prebiotic improve the growth performance and concentration of potentially prebiotic oligosaccharides in the ileum of broiler chickens

1. The objective of this study was to investigate the effect of supplementing broiler diets with xylanase or xylo- oligosaccharide (XOS) on growth performance, the concentration of non-starch polysaccharide (NSP) hydrolysis products in the ileum and concentration of short chain fatty acids (SCFA) in the caeca of broiler chickens.2. In total, 500 male Ross 308 broilers were used in this 29-day (d) study. The treatments were organised into a 2 × 2 plus 1 factorial arrangement consisting of two additives (xylanase or XOS) at two levels (low or high) plus a control treatment with no additives. This gave five treatments with 100 birds in each treatment group. The diets were slightly deficient in protein by 20 g/kg and energy by 1 MJ/kg.3. On d 14 and 28, two birds per pen were euthanised, the caeca content collected and analysed for short chain fatty acid (SCFA) concentration. On d 29, six birds per pen were euthanised and ileal digesta were collected and analysed for the concentration of NSP fractions.4. On d 14, caecal acetic acid, iso-butyric acid, iso-valeric acid, n-valeric acid and total SCFA concentrations were significantly greater (P ≤ 0.05) when diets were supplemented with XOS compared with xylanase.5. Ileal concentration of arabinose, galactose and glucuronic acid (GlucA2) were significantly greater (P ≤ 0.05) in the insoluble NSP fraction when diets were supplemented with a high level of xylanase, compared with the control treatment. Ileal concentration of fructose was significantly greater (P ≤ 0.05) in the water soluble NSP when a high level of xylanase or low level of XOS were included in the diet compared with the control.6. It was concluded that xylanase and XOS had similar effects on NSP concentration and SCFA in the caeca, although there was little effect on performance. This observation demonstrated further benefits of xylanase supplementation in wheat-based broiler diets beyond digesta viscosity reduction and the release of extra nutrients.

Effect of disulfide bridge on hydrolytic characteristics of xylanase from Penicillium janthinellum

Highly efficient and stable enzymes are required for application in biotechnology, to meet the technical, environmental, and economic industrial demands. Xylanases are hemicellulolytic enzymes that degrade the heteroxylan constituent of the lignocellulosic plant cell wall. In this study, an acidic xylanase designated Pjxyn (pH 4.0) from Penicillium janthinellum was engineered by the introduction of a disulfide bridge. This strategy exploited the influence of the bridge on hydrolysis characteristics and enhanced hydrolysis was achieved. Three mutants [PjxynS(27)S(39), PjxynS(27)S(186), and PjxynS(39)S(186)] produced more xylose and xylobiose as hydrolysis products compared with the wild-type Pjxyn, when commercial xylans and lab-prepared water-insoluble corncob-xylan were used as the substrates, especial for the PjxynS(27)S(39) mutant, the content of xylose and xylobiose was 87.62% (using beechwood xylan) and 69.91% (using oat-spelt xylan) higher than that in the hydrolysis products of Pjxyn. Moreover, each mutant combined with the xylanase mutant T-XynFM effectively decreased the production of xylose with an optimum xylobiose yield. The findings demonstrate the potential industrial value of engineering xylanase to improve its hydrolytic properties and thermostability.

Influence of a cocktail of protease and xylanase in different energy densities of corn- and soybean-meal-based diet on growth performance, nutrient digestibility, carcass quality, and gas emission in broilers

A total of 480 one-day-old male Ross 308 broilers with an average initial body weight (BW) of 42 ± 1 g was randomly divided into four treatments (8 replicates/treatment, 15 birds/replicate) by their BW to evaluate the influence of a cocktail of protease and xylanase in different energy density of corn- and soybean-meal-based diet on broilers. This experiment lasted for 35 d and there were two phases; starter (1–18 d) and finisher (19–35 d). The experiment was a 2 × 2 factorial arrangement with two levels of metabolizable energy and the cocktail enzyme with 200 mg of protease kg−1 diet and 100 FXU xylanase kg−1 diet. Both high-nutrient density and cocktail enzyme supplementation increased (P < 0.05) the body weight gain (BWG) during day 1–18 and day 1–35 as well as dry matter retention on day 35. Broilers fed the high-nutrient-density diets had higher (P < 0.05) energy retention on day 35 and relative breast muscle weight. Broilers fed the cocktail enzyme diets significantly increased nitrogen (N) retention and decreased the levels of ammonia (NH3) and hydrogen sulphide (H2S) emission. In conclusion, dietary supplementation of the cocktail enzyme component improved BWG, N retention, and reduced excreta noxious gas emission in broilers.

Effects of nutrient variability in corn and xylanase inclusion on broiler performance, nutrient utilisation, and volatile fatty acid profiles

The objective of the trial was to determine the impact of corn source and xylanase on broiler performance, digestibility, and volatile fatty acid (VFA) profiles. Six corn samples were obtained from different regions of the US. Twelve treatments were derived using corn source, with each corn diet being fed with or without xylanase. Three dietary phases were used throughout the trial, starter (d 1–18), grower (d 19–31), and finisher (d 32–41). On d 18 and 41, ileal and excreta contents were collected for the determination of ileal digestible energy (IDE), ileal energy and nitrogen digestibility coefficients (IEDC and INDC), apparent metabolisable energy (AME), and caecal VFA profiles. Day 18 body weight (BW) was affected by corn source and varied between 724 and 764g (P = 0.001). For d 31 BW, there was an interaction of corn source with xylanase (P = 0.001), with the effect of xylanase being inconsistent. The effect of xylanase on feed conversion ratio (FCR) during the grower phase depended on corn source (interactive term, P = 0.021). Xylanase reduced (P = 0.026) FCR during the finisher phase (1.943 vs. 1.992). Variation of corn source influenced digestibility on all evaluated parameters. A range of 152 and 213 kcal/kg for IDE was observed on d 18 and 41, respectively (P = 0.005 and 0.001). The range of AME was 176 kcal/kg on d 18 of age which increased to 194 kcal/kg on d 41. Nitrogen digestibility was influenced by corn source, with an observed range of 4.4 and 6.1% for d 18 and 41, respectively, amongst all corn sources (P = 0.001). Xylanase increased (P = 0.031) the concentration of butyrate in the caecum on d 18. On d 41, an interaction between corn source and xylanase was observed with isovalerate in the caecal contents (P = 0.038). These data demonstrate the impact of varying corn nutrient profiles on nutrient utilisation and growth performance.

Supplementing the feeds of layer pullets, at different ages with two different fiber sources improves immune function

Two experiments were conducted to study the effects of lignocellulose supplementation on immune function in layer pullets at different stages of growth. Four-wk-old pullets (Experiment 1) were fed a control, diet (Diet C); Diet C plus 1% mixed soluble/insoluble fiber (Diet MF), or plus 1% insoluble fiber (Diet IF). At 7.5 wk-of-age, heterophil phagocytosis, and oxidative burst in Groups MF (328.5 beads/100 cells; 4,330.0 ΔRFU; relative fluorescent units) and IF (350.3; 5,264.4) were greater (P < 0.05) than Controls (303.4; 3,509.0). At 8 wk-of-age, Group MF and IF relative weights of bursa of Fabricius (0.57 g/100 g BW; 0.58 g /100 g BW), thymus glands (0.77; 0.78), and areas of Peyer's patches (PP) (2.7 cm2; 2.9 cm2) were higher (P < 0.05) than Controls (bursa, 0.50 g; thymus, 0.70 g; PP area, 1.8 cm2). In Experiment 2, 10-wk-old pullets were fed a control diet or diets containing 1.5% MF or IF for 8 wk. At 14 wk-of-age IF pullets had higher (P < 0.05) heterophil phagocytosis efficiency (447.9 beads/100 cells) than Controls (376.4) and MF and IF had greater (P < 0.05) oxidative burst (1,302.9 and 1,857.7 ΔRFU) than Controls (744.1). At 17 wk-of-age MF and IF had increased (P < 0.05) proliferation of T-lymphocytes (ConcanavalinA-stimulated) (100.4 and 103.1% of unstimulated cells) and B-lymphocytes (lipopolysaccharide-stimulated) (122.4 and 129.0) than Controls (ConA, 79.4; lipopolysaccharide, 106.6). At 18 wk-of-age, IF pullets were heavier (1,607.5 g, P < 0.05) than Controls (1,506.5 g), had heavier (P < 0.05) bursa of Fabricius (1.12 g) than MF and Control groups (0.98 g; 0.92 g) and cecal tonsils of MF (0.38 g) and IF (0.39 g) weighted more (P < 0.05) than Controls (0.33 g). Number of jejunal and ileal PP (10.0) in IF pullets was higher (P < 0.05) than Controls (7.1). These results indicate that both MF and IF can improve development of the immune system of young and grower pullets during periods of maturation and involution of lymphoid organs.

Effects of protease and non-starch polysaccharide enzyme on performance, digestive function, activity and gene expression of endogenous enzyme of broilers

Three hundred one-day-old male broiler chickens (Ross-308) were fed corn-soybean basal diets containing non-starch polysaccharide (NSP) enzyme and different levels of acid protease from 1 to 42 days of age to investigate the effects of exogenous enzymes on growth performance, digestive function, activity of endogenous digestive enzymes in the pancreas and mRNA expression of pancreatic digestive enzymes. For days 1-42, compared to the control chickens, average daily feed intake (ADFI) and average daily gain (ADG) were significantly enhanced by the addition of NSP enzyme in combination with protease supplementation at 40 or 80 mg/kg (p<0.05). Feed-to-gain ratio (FGR) was significantly improved by supplementation with NSP enzymes or NSP enzyme combined with 40 or 80 mg/kg protease compared to the control diet (p<0.05). Apparent digestibility of crude protein (ADCP) was significantly enhanced by the addition of NSP enzyme or NSP enzyme combined with 40 or 80 mg/kg protease (p<0.05). Cholecystokinin (CCK) level in serum was reduced by 31.39% with NSP enzyme combined with protease supplementation at 160 mg/kg (p<0.05), but the CCK level in serum was increased by 26.51% with NSP enzyme supplementation alone. After 21 days, supplementation with NSP enzyme and NSP enzyme combined with 40 or 80 mg/kg protease increased the activity of pancreatic trypsin by 74.13%, 70.66% and 42.59% (p<0.05), respectively. After 42 days, supplementation with NSP enzyme and NSP enzyme combined with 40 mg/kg protease increased the activity of pancreatic trypsin by 32.45% and 27.41%, respectively (p<0.05). However, supplementation with NSP enzyme and 80 or 160 mg/kg protease decreased the activity of pancreatic trypsin by 10.75% and 25.88%, respectively (p<0.05). The activities of pancreatic lipase and amylase were significantly higher in treated animals than they were in the control group (p<0.05). Supplementation with NSP enzyme, NSP enzyme combined with 40 or 80 mg/kg protease increased pancreatic trypsin mRNA levels by 40%, 44% and 28%, respectively. Supplementation with NSP enzyme and 160 mg/kg protease decreased pancreatic trypsin mRNA levels by 13%. Pancreatic lipase and amylase mRNA expression were significantly elevated in treated animals compared to the control group (p<0.05). These results suggest that the amount of NSP enzyme and acid protease in the diet significantly affects digestive function, endogenous digestive-enzyme activity and mRNA expression in broilers.

Sequence homolog-based molecular engineering for shifting the enzymatic pH optimum

Cell-free synthetic biology system organizes multiple enzymes (parts) from different sources to implement unnatural catalytic functions. Highly adaption between the catalytic parts is crucial for building up efficient artificial biosynthetic systems. Protein engineering is a powerful technology to tailor various enzymatic properties including catalytic efficiency, substrate specificity, temperature adaptation and even achieve new catalytic functions. However, altering enzymatic pH optimum still remains a challenging task. In this study, we proposed a novel sequence homolog-based protein engineering strategy for shifting the enzymatic pH optimum based on statistical analyses of sequence-function relationship data of enzyme family. By two statistical procedures, artificial neural networks (ANNs) and least absolute shrinkage and selection operator (Lasso), five amino acids in GH11 xylanase family were identified to be related to the evolution of enzymatic pH optimum. Site-directed mutagenesis of a thermophilic xylanase from Caldicellulosiruptor bescii revealed that four out of five mutations could alter the enzymatic pH optima toward acidic condition without compromising the catalytic activity and thermostability. Combination of the positive mutants resulted in the best mutant M31 that decreased its pH optimum for 1.5 units and showed increased catalytic activity at pH < 5.0 compared to the wild-type enzyme. Structure analysis revealed that all the mutations are distant from the active center, which may be difficult to be identified by conventional rational design strategy. Interestingly, the four mutation sites are clustered at a certain region of the enzyme, suggesting a potential "hot zone" for regulating the pH optima of xylanases. This study provides an efficient method of modulating enzymatic pH optima based on statistical sequence analyses, which can facilitate the design and optimization of suitable catalytic parts for the construction of complicated cell-free synthetic biology systems.

Impact of combined β-glucanase and xylanase enzymes on growth performance, nutrients utilization and gut microbiota in broiler chickens fed corn or wheat-based diets

The effects of a xylanase and β-glucanase (XB) blend (2,500 U of xylanase and 250 U of β-glucanase per kg of complete feed) on growth performance, nutrients utilization and digesta microbiota in broiler chickens were investigated. A total of 140 day-old male Ross 308 broiler chicks were randomly assigned to 7 replicate cages and fed experimental diets. Diets were based on either corn or wheat without or with supplemental XB. Performance was monitored weekly and excreta were collected from d 17 to 20 for nutrients digestibility and AMEn measurements. On d 21, jejunal contents were collected for viscosity determination whereas ileal and cecal contents were obtained for microbial analysis by Illumina sequencing. Microbial data were analyzed using QIIME and PLS-DA whilst other data were analyzed using SAS. Birds fed wheat diets had higher (P < 0.001) BWG (3.4%) than birds fed corn-based diet whilst birds fed XB had better BWG (4%) and FCR (7%) than birds fed non-XB diets. Birds fed wheat diet had higher (P < 0.001) NDF (46.5%) and less (P = 0.01) CP (-5.4%) digestibility compared to birds fed corn-based diet. XB reduced (P < 0.001) jejunal digesta viscosity to a greater extent in wheat diet (-31%) than in corn-based diet (-10%). Birds fed wheat-based diet with XB had higher (3.5%) starch digestibility than birds fed this diet without XB. Janthinobacterium was associated with non-XB corn-based diet, whereas Ruminococcus, Lachnospiraceae, Lactobacillaceae, Peptostreptococcaceae, Clostridiales, Acidovorax and Blautia were associated with XB corn-based diet in the ileum. A relatively similar microbiome clustering was observed in wheat-based treatments in the cecum. There were no significant (P ≥ 0.05) correlations between selected ileal or cecal bacterial taxa and AMEn. Diet impacted growth performance but XB was efficacious across diet types, implying that degradation of dietary fibrous components by feed enzymes may stimulate performance in young birds. Data provided significant insight on ileal and cecal microbial profile associated with the dietary types and XB; however their functional roles require further investigations.

Effects of thermo-resistant non-starch polysaccharide degrading multi-enzyme on growth performance, meat quality, relative weights of body organs and blood profile in broiler chickens

This research was conducted to study the performance and carcass parameters of broiler chickens fed diets supplemented with heat-treated non-starch polysaccharide degrading enzyme. A total of 432 one-day old Ross 308 broiler chickens were allocated to five treatments: (i) CON (basal diet), (ii) E1: CON + 0.05% multi-enzyme, (iii) E2: CON + 0.1% multi-enzyme, (iv) E3: CON + 0.05% thermo-resistant multi-enzyme and (v) E4: CON + 0.1% thermo-resistant multi-enzyme, each treatment consisted of six replications and 12 chickens in each replication. The chickens were housed in three floor battery cages during 28-day experimental period. On days 1-7, gain in body weight (BWG) improved by feeding the diets supplemented with thermo-resistant multi-enzyme. On days 7-21 and 1-28, chickens fed the diets containing thermo-resistant multi-enzyme showed improved (p < 0.05) BWG and feed conversion ratio (FCR) compared to CON group. Supplementing the diets with multi-enzyme or thermo-resistant multi-enzyme affected the percentage of drip loss on d 1 (p < 0.05). Drip loss percentage on days 3 and 5 and also meat colour were not affected significantly. Supplementing the diets with multi-enzyme or thermo-resistant multi-enzyme did not affect the relative weights of organs but compared to CON group, relative weight of breast muscle increased and abdominal fat decreased (p < 0.05). Among measured blood constituents, chickens fed supplemented diets with thermo-resistant multi-enzyme showed higher (p < 0.05) IgG. Counts of red and white blood cells and lymphocyte percentage were not affected. In conclusion, the results demonstrated that supplementing pelleted diets with thermo-resistant multi-enzyme improved performance of broiler chickens.

Effects of Xylanase Supplementation on Growth Performance, Nutrient Digestibility and Non-starch Polysaccharide Degradation in Different Sections of the Gastrointestinal Tract of Broilers Fed Wheat-based Diets

This experiment was performed to investigate the effects of exogenous xylanase supplementation on performance, nutrient digestibility and the degradation of non-starch polysaccharides (NSP) in different sections of the gastrointestinal tract (GIT) of broilers fed wheat-based diets. A total of 120 7-day-old Arbor Acres broiler chicks were randomly allotted to two wheat-based experimental diets supplemented with 0 or 1.0 g/kg xylanase. Each treatment was composed of 6 replicates with 10 birds each. Diets were given to the birds from 7 to 21 days of age. The results showed that xylanase supplementation did not affect feed intake, but increased body weight gain of broiler at 21 day of age by 5.8% (p<0.05) and improved feed-to-gain ratio by 5.0% (p<0.05). Xylanase significantly increased (p<0.05) ileal digestibilities of crude protein (CP) by 3.5%, starch by 9.3%, soluble NSP by 43.9% and insoluble NSP by 42.2% relative to the control group, respectively. Also, compared with the control treatment, xylanase addition increased (p<0.05) total tract digestibilities of dry matter by 5.7%, CP by 4.1%, starch by 6.3%, soluble NSP by 50.8%, and had a tendency to increase (p = 0.093) insoluble NSP by 19.9%, respectively. The addition of xylanase increased the concentrations of arabinose and xylose in the digesta of gizzard, duodenum, jejunum, and ileum (p<0.05), and the order of their concentration was ileum>jejunum>duodenum>>gizzard> caecum. The supplementation of xylanse increased ileal isomaltriose concentration (p<0.05), but did not affect the concentrations of isomaltose, panose and 1-kestose in the digesta of all GIT sections. These results suggest that supplementation of xylanase to wheat-based diets cuts the arabinoxylan backbone into small fragments (mainly arabinose and xylose) in the ileum, jejunum and duodenum, and enhances digestibilites of nutrients by decreasing digesta viscosity. The release of arabinose and xylose in the small intestine may also be the important contributors to the growth-promoting effect of xylanase in broilers fed wheat-based diets.

Immobilization of His-tagged recombinant xylanase from Penicillium occitanis on nickel-chelate Eupergit C for increasing digestibility of poultry feed

Recombinant xylanase 2 from Penicillium occitanis expressed with an His-tag in Pichia pastoris, termed PoXyn2, was immobilized on nickel-chelate Eupergit C by covalent coupling reaction with a high immobilization yield up to 93.49%. Characterization of the immobilized PoXyn2 was further evaluated. The optimum pH was not affected by immobilization, but the immobilized PoXyn2 exhibited more acidic and large optimum pH range (pH 2.0-4.0) than that of the free PoXyn2 (pH 3.0). The free PoXyn2 had an optimum temperature of 50 °C, whereas that of the immobilized enzyme was shifted to 65 °C. Immobilization increased both pH stability and thermostability when compared with the free enzyme. Thermodynamically, increase in enthalpy and free energy change after covalent immobilization could be credited to the enhanced stability. Immobilized xylanase could be reused for 10 consecutive cycles retaining 60% of its initial activity. It was found to be effective in releasing reducing sugar from poultry feed. Immobilization on Eupergit C is important due to its mechanical resistance at high pH and temperature. Hence, considerable stability and reusability of bound enzyme may be advantageous for its industrial application.

GH11 xylanases: Structure/function/properties relationships and applications

For technical, environmental and economical reasons, industrial demands for process-fitted enzymes have evolved drastically in the last decade. Therefore, continuous efforts are made in order to get insights into enzyme structure/function relationships to create improved biocatalysts. Xylanases are hemicellulolytic enzymes, which are responsible for the degradation of the heteroxylans constituting the lignocellulosic plant cell wall. Due to their variety, xylanases have been classified in glycoside hydrolase families GH5, GH8, GH10, GH11, GH30 and GH43 in the CAZy database. In this review, we focus on GH11 family, which is one of the best characterized GH families with bacterial and fungal members considered as true xylanases compared to the other families because of their high substrate specificity. Based on an exhaustive analysis of the sequences and 3D structures available so far, in relation with biochemical properties, we assess biochemical aspects of GH11 xylanases: structure, catalytic machinery, focus on their "thumb" loop of major importance in catalytic efficiency and substrate selectivity, inhibition, stability to pH and temperature. GH11 xylanases have for a long time been used as biotechnological tools in various industrial applications and represent in addition promising candidates for future other uses.

Multi-carbohydrase and phytase supplementation improves growth performance and liver insulin receptor sensitivity in broiler chickens fed diets containing full-fat rapeseed

The effect of a combination of carbohydrase and phytase enzymes on growth performance, insulin-like growth factor 1 gene expression, insulin status, and insulin receptor sensitivity in broiler chickens fed wheat-soybean meal diets containing 6% (starter) and 12% (grower-finisher) of full-fat rapeseed (canola type; low glucosinolate, low erucic acid) from 1 to 42 d of age was studied. A total of 510 one-day-old male broiler chickens were randomly assigned to 3 dietary treatments, with 17 pens per treatment and 10 birds per pen. The dietary treatments consisted of a control diet and P- and Ca-deficient diets supplemented with either phytase (500 U/kg) or a combination of phytase and a multi-carbohydrase enzyme (Superzyme OM). The diets were pelleted at 78 degrees C and were fed ad libitum throughout the starter (9 d), grower (18 d), and finisher (15 d) phases of the experiment. Over the entire trial, growth performance of birds fed the phytase-supplemented diet did not differ from birds fed the control diet. The use of phytase in combination with a multicarbohydrase enzyme improved (P = 0.007) the feed conversion ratio from 1.90 to 1.84. Insulin liver receptor sensitivity increased by 9.3 and 12.3% (P = 0.004) for the phytase- and the carbohydrase-phytase-supplemented diets, respectively. There was no effect of phytase alone or carbohydrase and phytase supplementation on total plasma cholesterol, high-density lipoprotein cholesterol, and blood glucose levels. However, low-density lipoprotein cholesterol decreased (P = 0.007) for the phytase-carbohydrase treatment. Gene expression of insulin-like growth factor 1 tended to decrease by 32% (P = 0.083) after phytase-carbohydrase supplementation. The combination of carbohydrase and phytase enzymes may serve as an attractive means of facilitating nutrient availability for digestion and thus enhance the feeding value of wheat-soybean meal-based diets containing full-fat rapeseed. However, the extent to which the effects of enzyme addition on insulin receptors are associated with growth performance of broiler chicken requires further research.