Effects of β-mannanase supplementation on intestinal health and growth of nursery pigs

Two experiments were conducted using 120 pigs to test the hypothesis that supplementation of β-mannanase could reduce digesta viscosity, enhance nutrient digestion, and improve intestinal health and growth of nursery pigs. In experiment 1, 48 crossbred barrows were randomly allotted to four treatments with increasing levels of β-mannanase at 0, 200, 400, and 600 U/kg in feeds. All pigs were euthanized on day 12 to collect jejunal digesta to measure digesta viscosity and ileal digesta to measure apparent ileal digestibility (AID) of dry matter (DM), gross energy (GE), neutral detergent fiber (NDF), and acid detergent fiber (ADF). In experiment 2, 72 nursery pigs were randomly allotted to three treatments with increasing levels of β-mannanase at 0, 400, and 600 U/kg in feeds. Plasma collected on day 9 was used to measure tumor necrosis factor-α (TNF-α), immunoglobulin G (IgG), malondialdehyde (MDA), and protein carbonyl (PC). All pigs were euthanized on day 10 to collect duodenal and jejunal tissues to evaluate the production of TNF-α, IL-6, and MDA, morphology, crypt cell proliferation, and expression of tight junction proteins in the jejunum. Data were analyzed using the MIXED procedure for polynomial contrasts and the NLMIXED procedure for broken-line analysis of SAS. In experiment 1, β-mannanase supplementation tended to have quadratic effects on digesta viscosity (P = 0.085) and AID of GE (P = 0.093) in the pigs. In experiment 2, jejunal digesta viscosity of the pigs was reduced (P < 0.05) when β-mannanase was supplemented at 360 U/kg of feed. β-Mannanase supplementation linearly reduced (P < 0.05) TNF-α, IgG, MDA, and PC in the duodenum, and TNF-α, IgG, and MDA in the jejunum of the pigs. β-Mannanase supplementation linearly increased (P < 0.05) villus height to crypt depth ratio and crypt cell proliferation in the jejunum. β-Mannanase supplementation tended to linearly improve (P = 0.083) expression of zonula occludens-1 in the jejunum. In conclusion, supplementation of β-mannanase at 360 U/kg reduced the digesta viscosity and up to 600 U/kg positively affected intestinal health and growth of pigs by reducing inflammation and oxidative stress whilst enhancing structure and barrier function in the jejunum.

Individual or combinational use of phytase, protease, and xylanase for the impacts on total tract digestibility of corn, soybean meal, and distillers dried grains with soluble fed to pigs

OBJECTIVE

This study was to evaluate the effects of individual or combinational use of phytase, protease, and xylanase on total tract digestibility of corn, soybean meal, and distillers dried grains with soluble (DDGS) fed to pigs.

METHODS

Each experiment had four 4×4 Latin squares using 16 barrows. Each period had 5-d adaptation and 3-d collection. All experiments had: CON (no enzyme); Phy (CON+phytase); Xyl (CON+xylanase); Pro (CON+protease); Phy+Xyl; Phy+Pro, Xyl+Pro, Phy+Xyl+Pro. Each Latin square had 'CON, Phy, Xyl, and Phy+Xyl'; 'CON, Phy, Pro, and Phy+Pro'; 'CON, Pro, Xyl, and Xyl+Pro'; and 'Phy+Xyl, Phy+Pro, Xyl+Pro, Phy+Xyl+Pro'.

RESULTS

The digestible energy (DE), metabolizable energy (ME), and nitrogen retention (NR) of corn were not affected by enzymes but the apparent total tract digestibility (ATTD) of phosphorus (P) was improved (p<0.01) by Phy. The DE and ATTD dry matter (DM) in soybean meal were increased (p<0.05) by Phy+Pro and the ATTD P was improved (p<0.01) by Phy, Phy+Pro, and Phy+Xyl. The DE, ME, and ATTD DM in DDGS were improved (p<0.05) by Phy+Xyl and the ATTD P was improved (p<0.01) by Phy, Phy+Pro, and Phy+Xyl.

CONCLUSION

Phytase individually or in combination with xylanase and protease improved the Ca and P digestibility of corn, soybean meal, and DDGS, from the hydrolysis of phytic acid. The supplementation of protease was more effective when combined with phytase and xylanase in the soybean meal and DDGS possibly due to a higher protein content in these feedstuffs. Xylanase was more effective in DDGS diets due to the elevated levels of non-starch polysaccharides in these feedstuffs. However, when xylanase was combined with phytase, it demonstrated a higher efficacy improving the nutrient digestibility of pigs. Overall, combinational uses of feed enzymes can be more efficient for nutrient utilization in soybean meal and DDGS than single enzymes.

Friend or Foe? Impacts of Dietary Xylans, Xylooligosaccharides, and Xylanases on Intestinal Health and Growth Performance of Monogastric Animals

This paper discusses the structural difference and role of xylan, procedures involved in the production of xylooligosaccharides (XOS), and their implementation into animal feeds. Xylan is non-starch polysaccharides that share a β-(1-4)-linked xylopyranose backbone as a common feature. Due to the myriad of residues that can be substituted on the polymers within the xylan family, more anti-nutritional factors are associated with certain types of xylan than others. XOS are sugar oligomers extracted from xylan-containing lignocellulosic materials, such as crop residues, wood, and herbaceous biomass, that possess prebiotic effects. XOS can also be produced in the intestine of monogastric animals to some extent when exogenous enzymes, such as xylanase, are added to the feed. Xylanase supplementation is a common practice within both swine and poultry production to reduce intestinal viscosity and improve digestive utilization of nutrients. The efficacy of xylanase supplementation varies widely due a number of factors, one of which being the presence of xylanase inhibitors present in common feedstuffs. The use of prebiotics in animal feeding is gaining popularity as producers look to accelerate growth rate, enhance intestinal health, and improve other production parameters in an attempt to provide a safe and sustainable food product. Available research on the impact of xylan, XOS, as well as xylanase on the growth and health of swine and poultry, is also summarized. The response to xylanase supplementation in swine and poultry feeds is highly variable and whether the benefits are a result of nutrient release from NSP, reduction in digesta viscosity, production of short chain xylooligosaccharides or a combination of these is still in question. XOS supplementation seems to benefit both swine and poultry at various stages of production, as well as varying levels of XOS purity and degree of polymerization; however, further research is needed to elucidate the ideal dosage, purity, and degree of polymerization needed to confer benefits on intestinal health and performance in each respective species.

Effects of supplemental xylanase on health of the small intestine in nursery pigs fed diets with corn distillers' dried grains with solubles

Forty pigs [10.7 ± 1.2 kg initial body weight (BW) at 6 wk of age] were used in a 21-d study to evaluate the effects of supplemental xylanase (Hostazym X 100, Huvepharma, Inc., Peachtree City, GA) in nursery diets on digesta viscosity, nutrient digestibility, health of the small intestine, and growth performance when supplemented with corn distillers' dried grains with solubles (DDGS). Pigs were individually housed and randomly allotted to four treatments in a 2 × 2 factorial arrangement (n = 20/factor, 0% or 30% DDGS and 0 or 1,500 endo-pentosanase unit/kg xylanase as two factors) based on sex and initial BW. Feed intake and BW were recorded weekly. On day 15 of the study, TiO2 in diets (0.3%) was used as an indigestible marker to calculate apparent ileal digestibility (AID). Plasma samples were collected on day 19 to measure tumor necrosis factor-alpha (TNF-α), malondialdehyde, and peptide YY. On day 21, all pigs were euthanized to collect tissues from duodenum, jejunum, and colon to measure morphology, TNF-α, and malondialdehyde concentrations. Distal jejunal digesta were collected to measure viscosity. Ileum digesta were collected to measure AID of nutrients. During the entire period, supplemental xylanase increased (P < 0.05) average daily gain (ADG; 616 to 660 g/d) of nursery pigs, whereas DDGS (0 or 30%) did not affect ADG. On week 3, average daily feed intake (ADFI) was increased (P < 0.05) when fed DDGS (1,141 to 1,267 g/d) and there was an interaction (P < 0.05) between two factors indicating that supplemental xylanase decreased ADFI when DDGS was used in a diet. Use of DDGS increased (P < 0.05) viscosity [1.86 to 2.38 centipoise (cP)], whereas supplemental xylanase reduced (P < 0.05) viscosity (2.27 to 1.96 cP) of jejunal digesta. The AID of dry matter (DM) and gross energy (GE) were improved (P < 0.05) by supplemental xylanase. Plasma TNF-α was decreased (P < 0.05, 108.5 to 69.9 pg/mL) by supplemental xylanase. Use of DDGS reduced (P < 0.05) villus height:crypt depth ratio (1.46 to 1.27), whereas supplemental xylanase increased (P < 0.05) the crypt depth (360 to 404 µm) in duodenum. In conclusion, feeding a diet with 30% DDGS to nursery pigs for 3 wk had no negative effect on growth performance, whereas reduced AID of DM and GE, increased TNF-α level in colon tissue, and reduced the ratio of villus height to crypt depth. Dietary supplementation of xylanase reduced digesta viscosity improving AID of nutrients, reduced inflammatory response, and altered intestinal morphology, collectively improving ADG of nursery pigs regardless of the use of DDGS in a diet.

Improving the catalytic efficiency of thermostable Geobacillus stearothermophilus xylanase XT6 by single-amino acid substitution

Directed evolution using error-prone polymerase chain reaction was employed in the current study to enhance the catalytic efficiency of a thermostable Geobacillus stearothermophilus xylanase XT6 parent. High-throughput screening identified two variants with enhanced activity. Sequencing analysis revealed the presence of a single-amino acid substitution (P209L or V161L) in each variant. The maximum activity of mutant V161L and P209L was at 85°C and 70°C, respectively. Both mutants exhibited maximum activity at pH 7. The thermal and alkaline tolerance of mutant V161L only were markedly improved. The two mutants were more resistant to ethanol inhibition than the parent. Substrate specificity of the two mutants was shifted from beechwood xylan to birchwood xylan. The potential of the two mutants to hydrolyze rice straw and sugarcane bagasse increased. Both turnover number (kcat) and catalytic efficiency (kcat/kM) increased 12.2- and 5.7-folds for variant P209L and 13- and 6.5-folds for variant V161L, respectively, towards birchwood xylan. Based on the previously published crystal structure of extracellular G. stearothermophilus xylanase XT6, V161L and P209L mutation locate on βα-loops. Conformational changes of the respective loops could potentiate the loop swinging, product release and consequently result in enhancement of the catalytic performance.

Improvement of the catalytic efficiency of a hyperthermophilic xylanase from Bispora sp. MEY-1

Extremophilic xylanases have attracted great scientific and industrial interest. In this study, a GH10 xylanase-encoding gene, Xyl10E, was cloned from Bispora sp. MEY-1 and expressed in Pichia pastoris GS115. Deduced Xyl10E shares the highest identities of 62% and 57% with characterized family GH10 xylanases from Talaromyces leycettanus and Penicillium canescens (structure 4F8X), respectively. Xyl10E was most active at 93 to 95°C and pH 4.0, retained more than 75% or 48% of the initial activity when heated at 80°C or 90°C for 30 min, respectively, and hardly lost activity at pH 1.0 to 7.0, but was completely inhibited by SDS. Two residues, A160 and A161, located on loop 4, were identified to play roles in catalysis. Mutants A160D/E demonstrated higher affinity to substrate with lower K_m values, while mutants A161D/E mainly displayed elevated V_max values. All of these mutants had significantly improved catalytic efficiency. According to the molecular dynamics simulation, the mutation of A160E was able to affect the important substrate binding site Y204 and then improve the substrate affinity, and the mutation of A161D was capable of forming a hydrogen bond with the substrate to promote the substrate binding or accelerate the product release. This study introduces a highly thermophilic fungal xylanase and reveals the importance of loop 4 for catalytic efficiency.

Improvement of the catalytic performance of a hyperthermostable GH10 xylanase from Talaromyces leycettanus JCM12802

A xylanase gene of GH 10, Tlxyn10A, was cloned from Talaromyces leycettanus JCM12802 and expressed in Pichia pastoris. Purified recombinant TlXyn10A was acidic and hyperthermophilic, and retained stable over the pH range of 2.0-6.0 and at 90°C. Sequence analysis of TlXyn10A identified seven residues probably involved in substrate contacting. Three mutants (TlXyn10A_P, _N and _C) were then constructed by substituting some or all of the residues with corresponding ones of hyperthermal Xyl10C from Bispora sp. MEY-1. TlXyn10A_P with mutations at subsites +2 to +4 exhibited improved specific activity (by 0.44-fold) and pH stability (2.0-10.0). Molecular dynamics simulation analysis indicated that mutations E229I and F232E probably weaken the substrate affinity at subsites +3 to +4, and G149D may introduce a new hydrogen bond. These modifications altogether account for the improved performance of TlXyn10A_P. Moreover, TlXyn10A_P was able to hydrolyze wheat straw persistently, and has the application potentials in various industries.

Dietary supplementation with xylanase-expressing B. amyloliquefaciens R8 improves growth performance and enhances immunity against Aeromonas hydrophila in Nile tilapia (Oreochromis niloticus)

Bacillus amyloliquefaciens has attracted attention as a probiotic in aquaculture due to its immunostimulatory activity against pathogenic infection. Xylanases are extensively used in animal feed to degrade plant ingredients, enhancing nutrient utilization and increasing the growth rate of various animals. In the present study, the effects of dietary supplementation with B. amyloliquefaciens and xylanase-expressing B. amyloliquefaciens R8 on the growth of Nile tilapia (Oreochromis niloticus) and immunity against Aeromonas hydrophila were evaluated. The results showed that the xylanase activity in the intestine, weight gain (WG), feed efficiency (FE) and condition factor (CF) of Nile tilapia fed B. amyloliquefaciens R8 for 2 months were significantly increased compared with those of the fish fed the control diet and B. amyloliquefaciens. Moreover, the mRNA expression of growth- and metabolism-related genes, such as insulin-like growth factor-1 (igf-1), glucokinase (GK), glucose-6-phosphate 1-dehydrogenase (G6PD), and glucose-6-phosphatase (G6Pase), was significantly induced in Nile tilapia fed administered B. amyloliquefaciens R8, and this group also exhibited a higher survival rate than the control fish following a challenge with A. hydrophila. The phagocytic activity and respiratory burst activity of head kidney leukocytes as well as the serum lysozyme activity of B. amyloliquefaciens R8-fed Nile tilapia were significantly higher than those of fish fed the control diet for 2 months. Superoxide dismutase (SOD) levels in the head kidney leukocytes of Nile tilapia fed B. amyloliquefaciens R8 differed from those of fish fed the control diet, but this was not significant. These results indicate that dietary supplementation with xylanase-expressing B. amyloliquefaciens R8 improves growth performance and enhances immunity and disease resistance against A. hydrophila in Nile tilapia.