Impact of strain and dose of live yeast and yeast derivatives on in vitro ruminal fermentation of a high-grain diet at two pH levels

2018 ◽  
Vol 98 (3) ◽  
pp. 477-487 ◽  
Author(s):  
P.X. Jiao ◽  
Z.X. He ◽  
S. Ding ◽  
N.D. Walker ◽  
Y.Y. Cong ◽  
...  
Keyword(s):  
Positive Control ◽  
Gas Production ◽  
Additional Treatment ◽  
Ruminal Fermentation ◽  
Selenomonas Ruminantium ◽  
Copy Numbers ◽  
Randomized Design ◽  
Ph Level ◽  
Live Yeast

The objective of this study was to determine the effects of live yeast (LY) or yeast derivatives (YD) on gas production (GP), dry matter (DM) disappearance (DMD), fermentation characteristics, and microbial profiles in batch culture. The study was a completely randomized design with a factorial arrangement: 2 media pH × 5 yeasts × 4 dosages. An additional treatment of monensin (Mon) was added as a positive control for each pH level. Media pH was low (5.8) and high (6.5); the yeasts were three LY (LY1-3) and two YD (YD4-5); and doses were 0, 4 × 106, 8 × 106, and 1.6 × 107 cfu mL−1 for LY and 0, 15, 30, and 60 mg bottle−1 for YD. Substrate consisted of 10% silage and 90% concentrate (DM basis) and samples were incubated for 24 h. Media pH of 6.5 vs. 5.8, increased (P < 0.01) GP, DMD, and volatile fatty acid (VFA) concentrations but decreased (P < 0.01) NH3-N concentration and copy numbers of Ruminococcus albus, Ruminococcus flavefaciens, and Selenomonas ruminantium. Increasing dose of LY2 linearly (P < 0.05) increased DMD. Total VFA concentration was greater with LY2 (P < 0.01) than LY3 and YD5 at pH 6.5. Overall, adding yeast products improved (P < 0.05) DMD at pH 5.8, and increased VFA concentration compared with Mon. These results indicate that in vitro GP and DMD of a high-grain diet varied with source and dose of yeast supplementation. Some yeast products have the potential to improve fermentation of feedlot diets when supplemented at appropriate doses.

scholarly journals Inclusion of Red Osier Dogwood in High-Forage and High-Grain Diets Affected in Vitro Rumen Fermentation

2018 ◽  
Vol 18 (2) ◽  
pp. 453-467 ◽  
Author(s):  
Lingyun Y. Wei ◽  
Peixin X. Jiao ◽  
Trevor W. Alexander ◽  
Wen Zhu Yang
Keyword(s):  
Positive Control ◽  
Barley Grain ◽  
Gas Production ◽  
Additional Treatment ◽  
Starch Digestion ◽  
Randomized Design ◽  
Rumen Acidosis ◽  
High Forage ◽  
Barley Silage

Abstract Red osier dogwood (ROD) is an abundant shrub plant in Canada and other places in the world. It is rich in antioxidants such as quercetin, gallic acid and tyrosol. The objective of this study was to evaluate the effects of substituting barley silage with ROD in high-forage (HF) or high-grain (HG) diets on gas production (GP), dry matter (DM) disappearance (DMD) and fermentation characteristics in ruminal batch cultures. The study was a randomized design with 2 media pH (5.8 vs. 6.5) × 4 doses of ROD. An additional treatment of monensin and tylosin was added as a positive control for each pH level. The basic diet consisted of 60% barley silage and 40% barley grain for HF or 15% silage and 85% grain for HG diet. The barley silage was partly replaced with ROD at 0, 3, 6 or 12% in both diets (DM basis). Each diet was incubated for 24 h in culture bottles with three replicates for each treatment combination, and three runs on different days. The GP and DMD were greater (P<0.01) with media pH 6.5 vs. pH 5.8. The DMD linearly (P<0.01) decreased at pH 5.8 with increasing levels of ROD. Increasing ROD levels also linearly (P<0.01) decreased total VFA concentration and the proportion of propionate, and increased (P<0.01) the acetate to propionate ratio (A:P) at pH 5.8. Compared to the antibiotic treatment, the inclusion of ROD resulted in lower (P<0.02) DMD at pH 5.8, and a greater (P<0.01) proportion of acetate but a lower (P<0.01) proportion of propionate. These results indicated that the DMD of diets and the fermentation pattern were adversely affected by ROD at pH 5.8. However, the increased A:P along with the decreased DMD at pH 5.8, suggested a lower impact on fibre digestion than on starch digestion by ROD. Feeding ROD may therefore potentially reduce the incidence of rumen acidosis resulting from feeding HG diets to ruminants by decreasing starch digestion in the rumen.

PSXIV-14 Supplementation of high-grain diet with red osier dogwood affects in vitro digestibility and fermentation characteristics

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 477-477
Author(s):  
Wenzhu Yang
Keyword(s):  
Control Diet ◽  
Antimicrobial Properties ◽  
Positive Control ◽  
Gas Production ◽  
In Vitro Digestibility ◽  
Randomized Design ◽  
Rumen Acidosis ◽  
Barley Silage ◽  
And Control

Abstract Red osier dogwood (ROD) is a native shrub plant rich in phenolic compounds with antimicrobial properties. The objective of this study was to evaluate the effects of substituting barley silage with either raw ROD or ROD extract (RODE) in high-grain (HG) diet under a low media pH (5.8) on gas production (GP), dry matter (DM) disappearance (DMD) and fermentation characteristics in batch cultures. The study was a completely randomized design with 4 treatments: 1) control diet (10% barley silage and 90% barley concentrate, DM basis), control diet supplemented with 2) monensin (30 mg/kg diet DM; positive control), 3) substitution of 3% ROD or 4) 3% RODE for an equal portion of silage. Inoculum was obtained from 2 ruminally fistulated beef heifers offered the HG diet. Substrate ground (1 mm) was incubated for 24 h and the experiment repeated twice. The GP did not differ among treatments (147 ml/g DM), but the DMD differed (P &lt; 0.02) at highest for control (69.4%), lowest for ROD (58.4%) and intermediate for other treatments (64.1%). Total volatile fatty acid (VFA) concentration (mM) tended (P&lt; 0.08) to be lower with ROD (80.5) and monensin (80.1) than control (83.9). Acetate proportion was greater (P = 0.02) with ROD (46.2%) and RODE (46.9%) than control (42.4%) and monensin (42.3%). However, the propionate proportion was greater (P = 0.05) with monensin (32.1%) than other treatments (averaged 30.1%). Consequently, acetate to propionate ratio (A:P) of ROD (1.52) and RODE (1.56) was higher than monensin (1.32; P &lt; 0.01) and control (1.44; P &lt; 0.08). Differences in variables measured between ROD and RODE were minimal. These results indicated that the decreased DMD along with increased A:P with addition of ROD or RODE suggests that both ROD and RODE may be beneficial to HG fed cattle for reducing risk of rumen acidosis without negatively impacting fibre digestion.

scholarly journals Roughage to Concentrate Ratio and Saccharomyces cerevisiae Inclusion Could Modulate Feed Digestion and In Vitro Ruminal Fermentation

2020 ◽  
Vol 7 (4) ◽  
pp. 151
Author(s):  
Kampanat Phesatcha ◽  
Burarat Phesatcha ◽  
Metha Wanapat ◽  
Anusorn Cherdthong
Keyword(s):  
Saccharomyces Cerevisiae ◽  
High Ratio ◽  
Gas Production ◽  
Control Treatment ◽  
Ruminal Fermentation ◽  
Dry Matter Digestibility ◽  
Ch4 Production ◽  
Feed Digestibility ◽  
Live Yeast

The objective of this research was to investigate the effect of the roughage-to-concentrate (R:C) ratio and the addition of live yeast (LY) on ruminal fermentation characteristics and methane (CH4) production. The experimental design was randomly allocated according to a completely randomized design in a 4 × 4 factorial arrangement. The first factor was four rations of R:C at 80:20, 60:40, 40:60, and 20:80, and the second factor was an additional four doses of Saccharomyces cerevisiae (live yeast; LY) at 0, 2.0 × 106, 4.0 × 106, and 6.0 × 106 colony-forming unit (cfu), respectively. For the in vitro method, during the incubation, the gas production was noted at 0, 1, 2, 4, 6, 8, 10, 12, 18, 24, 48, 72, and 96 h. The rumen solution mixture was collected at 0, 4, 8, 12, and 24 h of incubating after inoculation. Cumulative gas production at 96 h was highest in the R:C ratio, at 20:80, while the addition of LY improves the kinetics and accumulation of gas (p > 0.05). Maximum in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD) at 24 h after incubation were achieved at the R:C ratio 20:80 and the addition of LY at 6 × 106 cfu, which were greater than the control by 13.7% and 12.4%, respectively. Ruminal pH at 8 h after incubation decreased with an increased proportion of concentrates in the diet, whereas it was lowest when the R:C ratio was at 20:80. Increasing the proportion of a concentrate diet increased total volatile fatty acid (TVFA) and propionic acid (C3), whereas the acetic acid (C2) and C2-to-C3 ratios decreased (p < 0.05). TVFA and C3 increased with the addition of LY at 6 × 106 cfu, which was greater than the control by 11.5% and 17.2%, respectively. No interaction effect was observed between the R:C ratio and LY on the CH4 concentration. The calculated ruminal CH4 production decreased with the increasing proportion of concentrates in the diet, particularly the R:C ratio at 20:80. The CH4 production for LY addition at 6 × 106 cfu was lower than the control treatment by 17.2%. Moreover, the greatest populations of bacteria, protozoa, and fungi at 8 h after incubation were found with the addition of LY at 6 × 106 cfu, which were higher than the control by 19.0%, 20.7%, and 40.4%, respectively. In conclusion, a high ratio of roughage and the concentrate and addition of LY at 6.0 × 106 cfu of the total dietary substrate could improve rumen fermentation, improve feed digestibility, and reduce the CH4 production.

scholarly journals Screening of Cyanide-Utilizing Bacteria from Rumen and In Vitro Evaluation of Fresh Cassava Root Utilization with Pellet Containing High Sulfur Diet

2020 ◽  
Author(s):  
Rittikeard Prachumchai ◽  
Anusorn Cherdthong ◽  
Metha Wanapat
Keyword(s):  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
In Vitro Study ◽  
Gas Production ◽  
Ruminal Fermentation ◽  
Cassava Root ◽  
Randomized Design ◽  
Completely Randomized Design

The current work aimed to screen the ruminal cyanide-utilizing bacteria and evaluate the influence of fresh cassava root (FCR) and pellets containing high sulfur (PELFUR) on cyanide content, kinetics of gas, in vitro degradability, and ruminal fermentation. The experiment was conducted in a Completely randomized design (CRD) for a screening of cyanide-utilizing bacteria and the dietary treatments were the level of cyanide at 0, 150, 300, and 450 ppm. A 5 &times; 3 factorial arrangement in a Completely randomized design was used for in vitro study. Factor A was the level of FCR at 0, 260, 350, 440, and 530 g/kg of 0.5 g dry matter (DM) substrate, and factor B was the level of PELFUR at 0, 15, and 30 g/kg DM substrate. Adding different doses of cyanide significantly affected cyanide-utilizing rumen bacterial growth (p &lt; 0.05). Increasing the concentration of cyanide from 0 to 150 and 150 to 300 ppm, resulted in an increase in cyanide-utilizing rumen bacteria of 38.2% and 15.0%, respectively. Increasing the FCR level to more than 260 g/kg of 0.5 g substrate could increase cumulative gas production (p &lt; 0.05), whereas increasing doses of PELFUR from 15 to 30 g/kg increased the cumulative gas production when compared with that of 0 g/kg PELFUR (p &lt; 0.05). Cyanide concentration in rumen fluid decreased with PELFUR (p &lt; 0.05) supplementation. Degradability of in vitro dry matter and organic matter following incubation increased at 12 and 24 h due to PELFUR supplementation with FCR and increased additionally with 15 g/kg PELFUR (p &lt; 0.05) in 440 g/kg FCR. Proportions of the total volatile fatty acids, acetic acid (C2), propionic acid (C3), and butyric acid, as well as the ratio of C2 to C3 among supplementations with FCR (p &lt; 0.05) were significantly different. As the proportion of FCR increased to 530 g/kg of the substrate, the volume of C3 increased by 14.6%. This is the first finding of bacteria in the rumen capable of utilizing cyanide, and cyanide might function as a nitrogen source for bacterial cell synthesis. Inclusion of FCR of 530 g/kg with 30 g/kg PELFUR could increase the cumulative gas production, the bacterial population, the in vitro degradability, the proportion of C3, and the rate of the disappearance of cyanide.

scholarly journals EXTRATO DE MAMONA COMO MANIPULADOR DA FERMENTAÇÃO RUMINAL

Nativa ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 289
Author(s):  
Pâmella Moraes Franco ◽  
Márcia Rodrigues Carvalho Oliveira ◽  
Joao Rafael de Assis ◽  
Jurandy Gouveira Junior ◽  
Rodrigo Nazare Santos Torres ◽  
...  
Keyword(s):  
Gas Production ◽  
Control Treatment ◽  
Energetic Efficiency ◽  
Ruminal Fermentation ◽  
Ruminal Ph ◽  
Dietary Condition ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
High Forage

Objetivou-se investigar os efeitos da adição do extrato de farelo de mamona (EFM) sobre o perfil da fermentação ruminal in vitro em dietas com alto e baixo teor de forragem. Utilizou-se ensaio de incubação ruminal in vitro com dois controles, um negativo (sem aditivo) e um positivo (monensina sódica) e EFM liofilizado (20, 40 e 60 mg/frasco). Em condições de alto teor de forragem na dieta, a adição do EFM aumentou o pH do meio e a concentração de acetato, reduziu a produção de gás, mas não afetou a produção de gás por unidade de matéria seca (MS) digerida em relação ao tratamento controle. Em comparação com monensina sódica, o EFM reduziu as concentrações de propionato e amônia e aumentou a produção de gás por unidade de MS digerida. Em condições de baixo teor de forragem, a adição do EFM reduziu o pH e potencial redox do meio em relação ao tratamento controle. Em comparação com a monensina sódica, o EFM reduziu o pH do meio e a produção total de gás, mas não afetou a produção de gás por unidade de MS digerida. O extrato de farelo de mamona destoxificado não apresenta potencial como manipulador da fermentação ruminal.Palavras-chave: amônia; digestibilidade; eficiência; metano. CASTOR BEAN EXTRACT AS A MANIPULATOR OF RUMINAL FERMENTATION ABSTRACT: Effects of the castorbean meal extract (CME) on ruminal in vitro were investigate in high and low forage diet conditions. For each dietary condition, one in vitro ruminal incubation experiment was conducted in a completely randomized design, with nine repetitions per treatment (three animal inoculum donators and three 48 hors-incubations). In high forage diet, CME increased ruminal pH acetate concentration, reduced gas production, but it did not affect the gas production per unit of digested dry matter (DM), in relation to control treatment. Compare to monensin sodium, CME reduced propionate and ammonia concentrations and increased gas production per unit of digested DM, indicating that CME reduces ruminal energetic efficiency. In low forage diet, CME reduced pH and redox potential compare to control. Compare to monensin sodium, CME reduced pH and gas production, but it did not affect gas production per unit of digested DM. Castorbean meal extract does not present potential as manipulator of the ruminal fermentation.Keywords: ammonia; digestibility; efficiency; methane.

scholarly journals Óleos essenciais como modificadores da fermentação ruminal em substituição a monensina sódica in vitro

2019 ◽  
Vol 68 (264) ◽  
pp. 576-581
Author(s):  
L. Antunes Stella ◽  
V. Rosa Prates ◽  
A. Zubieta ◽  
C. Bayer ◽  
J.O. Jardim Barcellos
Keyword(s):  
Gas Production ◽  
Control Treatment ◽  
Clove Oil ◽  
Ruminal Fermentation ◽  
Cinnamon Oil ◽  
Bitter Orange ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Fermentation Parameters

The objective of this study to evaluate the effect of secondary plant compounds present in essential oils in replacement of monensin on in vitro ruminal fermentation parameters. It was adopted a completely randomized design with nine treatments and four replicates. The treatments were: control (CON), monensin (MON), garlic oil (ALH), cinnamon oil (CAN), clove oil (CRA), mint oil (HOR), juniper oil (JUN), bitter orange oil (LAR), and melaleuca oil (MEL). The in vitro gas technique was used to record total gas production at 4, 8, 12 and 24 h after incubation. MON, CAN and CRA increased gas production Only the garlic and cinnamon treatments reduced the digestibility of organic matter in 20 and 26% in relation to the control treatment. Methane production reduced (P

scholarly journals Babassu mesocarp meal for ewe lambs feeding: In vitro ruminal fermentation and in vivo apparent digestibility

2020 ◽  
Vol 43 ◽  
pp. e51056
Author(s):  
Luciano Fernandes Sousa ◽  
Jhone Tallison Lira de Sousa ◽  
Érica Beatriz Schultz ◽  
Gilberto de Lima Macedo Júnior
Keyword(s):  
Block Design ◽  
Gas Production ◽  
Ruminal Fermentation ◽  
Test Technique ◽  
Ewe Lambs ◽  
Randomized Design ◽  
Ruminant Diets ◽  
Four Blocks

The purpose of the current study was to evaluate the in vitro fermentation (IVRF) and apparent in vivo digestibility (AIVD) of diets formulated with four inclusion levels of babassu mesocarp meal (BMM) (0.0; 7.5; 15.0 and 22.5%) in ewe lambs. The IVRF test was performed through the "Hohenheim Gas Test" technique, following a randomized complete block design, with four blocks (rumen fluids from four different bovines). Gas production was measured at 3, 6, 9, 12, 24, 48, 72, and 96 hours after incubation. For the AIVD trial, 20 ewe lambs were used in a completely randomized design with five replicates. The animals were housed in metabolic cages during the digestibility test. Diets with BMM showed lower fermentation levels than those without BMM. The BMM reduced the gas production per incubation time and dry matter effective degradability (DMED), possibly due to its chemical characteristics, or even to the influence of other factors, such as physical properties. The BMM negatively influenced the AIVD of DM. Thus, it can be stated that, despite being a starch source, BMM reduces ruminal fermentation parameters when included in ruminant diets, negatively interfering with diet digestibility. Therefore, its use should be cautious.

Effect of mixed live yeast and lactic acid bacteria on in vitro fermentation with varying media pH using a high-grain or high-forage diet

2021 ◽  
Author(s):  
Peixin Jiao ◽  
Fengchun Ma ◽  
Karen A. Beauchemin ◽  
Ousama AlZahal ◽  
Xiaolai Xie ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Gas Production ◽  
Yeast Saccharomyces Cerevisiae ◽  
In Vitro Fermentation ◽  
Randomized Design ◽  
Effects Of Media ◽  
High Forage ◽  
Live Yeast

Two experiments were conducted to assess the effects of media pH and mixtures (SCEF) of live yeast (Saccharomyces cerevisiae; SC) and lactic acid bacteria (Enterococcus faecium; EF) on gas production (GP), dry matter disappearance (DMD) and volatile fatty acid (VFA) concentrations in batch culture using either high-forage (HF) or high-grain (HG) diets. Diets were evaluated in separate experiments, each as a complete randomized design with 2 (media pH, 5.8 and 6.5) × 5 (control, 3 SCEF, monensin) factorial arrangement of treatments. The SCEF had varying ratios of SC:EF: 0:0 (control), 1.18:1 (SCEF1), 1.25:1 (SCEF2) and 1.32:1 (SCEF3), added on a log10 basis. For the HF diet, supplementation of SCEF had greater GP (P = 0.03) at pH 6.5, and greater DMD (P = 0.03) and VFA concentration (P < 0.01) at pH 5.8 and 6.5 than control. For the HG diet, acetate:propionate (A:P) ratio at pH 6.5 was greater (P = 0.05) for SCEF than control. Increasing ratio of SC to EF in SCEF linearly (P < 0.01) decreased GP and DMD and linearly increased acetate percentage at pH 6.5. These results suggest that optimizing the SC:EF ratio in a mixture of SCEF can help improve rumen fermentation.

scholarly journals Screening of Cyanide-Utilizing Bacteria from Rumen and In Vitro Evaluation of Fresh Cassava Root Utilization with Pellet Containing High Sulfur Diet

2021 ◽  
Vol 8 (1) ◽  
pp. 10
Author(s):  
Rittikeard Prachumchai ◽  
Anusorn Cherdthong ◽  
Metha Wanapat
Keyword(s):  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
In Vitro Study ◽  
Gas Production ◽  
Ruminal Fermentation ◽  
Production Parameters ◽  
Cassava Root ◽  
Randomized Design ◽  
Completely Randomized Design

Two experiments were undertaken to screen for ruminal cyanide-utilizing bacteria (Experiment 1), and to evaluate the influence of fresh cassava root (FCR) and pellets containing high sulfur (PELFUR) on cyanide content, gas production parameters, in vitro degradability, and ruminal fermentation (Experiment 2). Experiment 1 was conducted in a completely randomized design (CRD) for the screening of cyanide-utilizing bacteria and the dietary treatments consisted of cyanide at 0, 150, 300, and 450 ppm. In Experiment 2, a 5 × 3 factorial arrangement in a completely randomized design was used for the in vitro study. Factor A was the level of FCR at 0, 260, 350, 440, and 530 g/kg of dry matter (DM) substrate, and factor B was the level of PELFUR at 0, 15, and 30 g/kg DM substrate. In Experiment 1, adding different doses of cyanide significantly affected cyanide-utilizing rumen bacterial growth (p < 0.05). Increasing the concentration of cyanide from 0 to 150 and 150 to 300 ppm resulted in increases in cyanide-utilizing rumen bacteria of 38.2% and 15.0%, respectively. In Experiment 2, no interaction effects were found between FCR and PELFUR doses on gas production parameters (p > 0.05). Increasing the FCR level to more than 260 g/kg of DM substrate could increase cumulative gas production (p < 0.05). Increasing doses of PELFUR from 15 to 30 g/kg increased the cumulative gas production when compared with that of 0 g PELFUR/kg of DM substrate (p < 0.05). The cyanide concentration in rumen fluid decreased with PELFUR (p < 0.05) supplementation. Degradability of in vitro DM and organic matter following incubation increased at 12 and 24 h due to PELFUR supplementation with FCR and increased additionally with 15 g PELFUR/kg of DM substrate (p < 0.05) in 440 g FCR/kg of DM substrate. Proportions of the total volatile fatty acids, acetic acid (C2), propionic acid (C3), and butyric acid among supplementations with FCR (p < 0.05) were significantly different. In conclusion, the present results represent the first finding of bacteria in the rumen that are capable of utilizing cyanide, and suggests that cyanide might function as a nitrogen source for bacterial cell synthesis. The inclusion of FCR of 530 g/kg with 30 g PELFUR/kg of DM substrate could increase the cumulative gas production, the bacterial population, the in vitro degradability, the proportion of C3, and the rate of the disappearance of cyanide.

Efficacy of exogenous xylanases for improving in vitro fermentation of forages

2014 ◽  
Vol 153 (3) ◽  
pp. 538-553 ◽  
Author(s):  
Z. X. HE ◽  
L. Y. YANG ◽  
W. Z. YANG ◽  
K. A. BEAUCHEMIN ◽  
S. X. TANG ◽  
...  
Keyword(s):  
Volatile Fatty Acids ◽  
Xylanase Activity ◽  
Ammonia Nitrogen ◽  
Positive Control ◽  
Linear Increase ◽  
Gas Production ◽  
Pennisetum Purpureum ◽  
Ruminal Fermentation ◽  
Positive Effects

SUMMARYBatch cultures of mixed rumen micro-organisms were used to evaluate varying enzyme products with high xylanase activity (EPX), four of which were recombinant single xylanase activity developmental enzyme products (EPX1–EPX4, products of xylanase genes derived from Trichoderma harzianum, Trichoderma reesei, Orpinomyces and Aspergillus oryzae, respectively), for their potential to improve in vitro ruminal fermentation of three forages [maize (Zea mays) stover (MS), rice (Oryza sativa) straw (RS) and Guimu No. 1 grass (Pennisetum americanum×Pennisetum purpureum, GM)]. The enzyme product EPX5, derived from Trichoderma longibrachiatum, was used as a positive control that could improve in vitro fermentation of forages. Enzymes were supplied at dose rates of 0 (control), 20 (low), 50 (medium) and 80 (high) enzymic units of xylanase/g of dry matter (DM). There were no interactions between EPX and dose for the fermentation characteristics evaluated. Increasing EPX dose linearly increased gas production (GP) kinetic characters [i.e. asymptotic GP (VF), half time when GP is half of the theoretical maximum GP (t0·5), and initial fractional rate of degradation (FRD0)] and methane (CH4) production from RS and GM at 24 h, and increased degradability of DM at 24 h for MS and RS. A linear increase in degradability of neutral detergent fibre (NDF) of the three forages at 24 h was observed with increasing dose of EPX, but at 48 h only NDF degradability of RS was increased. There were differences in the effects of EPX on degradability of DM and NDF from RS at 24 h, with EPX4 having the highest and EPX1 having the lowest. In addition, increasing EPX dose linearly increased acetate proportion at 24 h and total volatile fatty acids (TVFA) at 48 h in MS. Increasing EPX dose linearly increased TVFA at 24 h, and ammonia-nitrogen (NH3-N) concentration at 48 h in RS. For GM, linear or quadratic effects of dose on acetate and butyrate concentration were observed at 24 and 48 h. The present study indicates that applying EPX to low-quality forages has the potential to improve rumen degradability and utilization. Furthermore, EPX from different sources differed in their effects when applied at the same dose rate, with the responses being forage-specific. For RS, the EPX derived from A. oryzae showed the greatest positive effects on forage degradation; whereas for MS and GM, the source of micro-organism where EPX gene was derived did not affect the degradation, with little difference among the EPX evaluated.

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