溶菌酶对瘤胃体外发酵、甲烷生成及微生物菌群结构的影响

【目的】通过体外静态模拟瘤胃发酵法研究溶菌酶对瘤胃发酵、甲烷生成及微生物菌群结构的影响。【方法】采用单因素多水平试验设计,溶菌酶添加水平分别为0(L-0,对照组)、0.1 mg/100 m L(L-0.1)、1 mg/100 m L(L-1)、10 mg/100 m L(L-10)和100 mg/100 m L(L-100),定时测定产气量和甲烷产量,培养24 h后,发酵液用于发酵参数和微生物菌群数量的q PCR测定,其中L-0、L-1和L-100三个组发酵液同时进行16S r RNA基因Illumina高通量测序。【结果】与对照组相比,低剂量溶菌酶添加(L-0.1组)不影响甲烷产量、氨氮浓度、干物质消失率、有机物消失率和总挥发性脂肪酸等瘤胃发酵参数(P0.05);随着剂量提高,L-1处理组甲烷产量、氨氮浓度显著降低(P0.05),丙酸浓度显著增加(P0.05),并且干物质消失率、有机物消失率和总挥发性脂肪酸不受影响(P0.05);而较高剂量组(L-10和L-100组)虽然甲烷产量显著降低,丙酸浓度显著增加(P0.05),但干物质消失率和有机物消失率也显著降低(P0.05)。q PCR结果显示高剂量组(L-100组)总菌、原虫、甲烷菌数量与对照组相比显著降低(P0.05),而L-0.1、L-1和L-10组总菌、真菌和原虫数量与对照组相比均无显著变化(P0.05)。高通量测序主成分分析(PCA)显示对照组与溶菌酶添加组间瘤胃细菌组成的明显区分,说明添加溶菌酶显著改变了瘤胃细菌菌群结构。溶菌酶通过增加月形单胞菌和琥珀酸弧菌等丙酸生成菌的相对丰度,使更多的氢被用于生成丙酸,导致甲烷产量降低;溶菌酶可抑制普雷沃氏菌和拟杆菌属等蛋白降解菌的生长,进而减少蛋白质过度降解,降低氨氮浓度。【结论】添加适宜浓度(1 mg/100 m L)的溶菌酶可通过调控瘤胃微生态改变瘤胃发酵模式,降低瘤胃甲烷和氨的生成,短期内并不影响饲料消化。     

Does Dietary Mitigation of Enteric Methane Production Affect Rumen Function and Animal Productivity in Dairy Cows?

It has been suggested that the rumen microbiome and rumen function might be disrupted if methane production in the rumen is decreased. Furthermore concerns have been voiced that geography and management might influence the underlying microbial population and hence the response of the rumen to mitigation strategies. Here we report the effect of the dietary additives: linseed oil and nitrate on methane emissions, rumen fermentation, and the rumen microbiome in two experiments from New Zealand (Dairy 1) and the UK (Dairy 2). Dairy 1 was a randomized block design with 18 multiparous lactating cows. Dairy 2 was a complete replicated 3 x 3 Latin Square using 6 rumen cannulated, lactating dairy cows. Treatments consisted of a control total mixed ration (TMR), supplementation with linseed oil (4% of feed DM) and supplementation with nitrate (2% of feed DM) in both experiments. Methane emissions were measured in open circuit respiration chambers and rumen samples were analyzed for rumen fermentation parameters and microbial population structure using qPCR and next generation sequencing (NGS). Supplementation with nitrate, but not linseed oil, decreased methane yield (g/kg DMI; P<0.02) and increased hydrogen (P<0.03) emissions in both experiments. Furthermore, the effect of nitrate on gaseous emissions was accompanied by an increased rumen acetate to propionate ratio and consistent changes in the rumen microbial populations including a decreased abundance of the main genus Prevotella and a decrease in archaeal mcrA (log₁₀ copies/ g rumen DM content). These results demonstrate that methane emissions can be significantly decreased with nitrate supplementation with only minor, but consistent, effects on the rumen microbial population and its function, with no evidence that the response to dietary additives differed due to geography and different underlying microbial populations.     

Effect of pH on Population and Fermentation in a Continuously Cultured Rumen Ecosystem

The effect of pH on rumen fermentation and microbial population was studied in a continuously cultured rumen ecosystem. A marked decrease in the production of volatile fatty acids and methane from alfalfa hay occurred when the cultures were maintained at pH values below 6.0. The decrease in acetate and methane production was greater than that of propionate production. The culture maintained at pH 6.7 contained the types of bacteria often found in high concentration in the rumen, whereas the culture maintained at pH 5.0 had a high percentage of bacteria which could not be identified with the major rumen bacteria found in rumens of animals fed alfalfa hay. Replacement of the bicarbonate-phosphate buffer used to maintain fermentor pH at 6.7 with phosphate alone did not greatly alter the fermentation products produced from a hay-concentrate substrate.     

Effects of the inclusion of Moringa oleifera seed on rumen fermentation and methane production in a beef cattle diet using the rumen simulation technique (Rusitec)

Moringa oleifera seeds are currently being used as a livestock feed across tropical regions of the world due to its availability and palatability. However, limited knowledge exists on the effects of the raw seeds on ruminant metabolism. As such, the rumen stimulation technique was used to evaluate the effects of substituting increasing concentrations of ground Moringa seeds (0, 100, 200 and 400 g/kg concentrate dry matter (DM)) in the diet on rumen fermentation and methane production. Two identical, Rusitec apparatuses, each with eight fermenters were used with the first 8 days used for adaptation and days 9 to 16 used for measurements. Fermenters were fed a total mixed ration with Urochloa brizantha as the forage. Disappearance of DM, CP, NDF and ADF linearly decreased (P<0.01) with increasing concentrations of Moringa seeds in the diet. Total volatile fatty acid production and the acetate to propionate ratio were also linearly decreased (P<0.01). However, only the 400 g/kg (concentrate DM basis) treatment differed (P<0.01) from the control. Methane production (%), total microbial incorporation of ¹⁵N and total production of microbial N linearly decreased (P<0.01) as the inclusion of Moringa seeds increased. Though the inclusion of Moringa seeds in the diet decreased CH₄ production, this arose from an unfavourable decrease in diet digestibility and rumen fermentation parameters.     

Changes in microbial community structure, methanogenesis and rumen fermentation in response to saponin-rich fractions from different plant materials

Aims:  Investigation of the effects of saponin-rich fractions on rumen fermentation, methane production and the microbial community.
Methods and Results:  Saponins were extracted from Carduus , Sesbania and Knautia leaves and fenugreek seeds. Two levels of saponin-rich fractions with a substrate were incubated using the Hohenheim gas method. Methane was measured using an infrared-based methane analyser and microbial communities using quantitative PCR. On addition of saponin-rich fractions, methane and short-chain fatty acid production was not affected. The protozoal counts decreased by 10–39%. Sesbania saponins decreased methanogen population by 78%. Decrease in ruminal fungal population (20–60%) and increase in Fibrobacter succinogenes (21–45%) and Ruminococcus flavefaciens (23–40%) were observed.
Conclusions:  The saponins evaluated possessed anti-protozoal activity; however, this activity did not lead to methane reduction. Fenugreek saponins seemed to have potential for increasing rumen efficiency. The saponins altered the microbial community towards proliferation of fibre-degrading bacteria and inhibition of fungal population.
Significance and Impact of the Study:  The uni-directional relationship between protozoal numbers and methanogenesis, as affected by saponins, is not obligatory. All saponins might not hold promise for decreasing methane production from ruminants.     

Factors affecting rumen methanogens and methane mitigation strategies

The rumen is a highly diverse ecosystem comprising different microbial groups including methanogens that consume a considerable part of the ruminant’s nutrient energy in methane production. The consequences of methanogenesis in the rumen may result in the low productivity and possibly will have a negative impact on the sustainability of the ruminant’s production. Since enteric fermentation emission is one of the major sources of methane and is influenced by a number of environmental factors, diet being the most significant one, a number of in vitro and in vivo trials have been conducted with different feed supplements (halogenated methane analogues, bacteriocins, propionate enhancers, acetogens, fats etc.) for mitigating methane emissions directly or indirectly, yet extensive research is required before reaching a realistic solution. Keeping this in view, the present article aimed to cover comprehensively the different aspects of rumen methanogenesis such as the phylogeny of methanogens, their microbial ecology, factors affecting methane emission, mitigation strategies and need for further study.     

The effect of pectin, corn and wheat starch, inulin and pH on in vitro production of methane, short chain fatty acids and on the microbial community composition in rumen fluid

Methane emission from livestock, ruminants in particular, contributes to the build up of greenhouse gases in the atmosphere. Therefore the focus on methane emission from ruminants has increased. The objective of this study was to investigate mechanisms for methanogenesis in a rumen fluid-based in vitro fermentation system as a consequence of carbohydrate source (pectin, wheat and corn starch and inulin) and pH (ranging from 5.5 to 7.0). Effects were evaluated with respect to methane and short chain fatty acid (SCFA) production, and changes in the microbial community in the ruminal fluid as assessed by terminal-restriction fragment length polymorphism (T-RFLP) analysis. Fermentation of pectin resulted in significantly lower methane production rates during the first 10 h of fermentation compared to the other substrates (P = 0.001), although total methane production was unaffected by carbohydrate source (P = 0.531). Total acetic acid production was highest for pectin and lowest for inulin (P < 0.001) and vice versa for butyric acid production from pectin and inulin (P < 0.001). Total propionic acid production was unaffected by the carbohydrate source (P = 0.791). Methane production rates were significantly lower for fermentations at pH 5.5 and 7.0 (P = 0.005), sustained as a trend after 48 h (P = 0.059), indicating that there was a general optimum for methanogenic activity in the pH range from 6.0 to 6.5. Decreasing pH from 7.0 to 5.5 significantly favored total butyric acid production (P < 0.001). Principle component analysis of T-RFLP patterns revealed that both pectin and pH 5.5 resulted in pronounced changes in the microbial community composition. This study demonstrates that both carbohydrate source and pH affect methane and SCFA production patterns, and the microbial community composition in rumen fluid.     

Resveratrol affects in vitro rumen fermentation,methane production and prokaryotic community composition in a time- and diet-specific manner

This study aimed to investigate the effect of resveratrol on methane production, rumen fermentation and microbial composition under high-concentrate (HC) and high-forage (HF) diets using the in vitro fermentation system. A total of 25 mg of resveratrol was supplemented into 300 mg of either HC or HF diet. Methane production, total volatile fatty acid (VFA) concentration, molar proportion of VFA, metabolites of resveratrol and prokaryotic community composition were measured after 12 and 24 h of in vitro fermentation. Resveratrol reduced methane production (ml per mg of dry matter degraded) by 41% and 60% under both HC and HF diets (P < 0.001), respectively, and this result could be associated with the lower abundance of Methanobrevibacter (P < 0.001) in response to resveratrol. The molar proportion of propionate was significantly higher in the resveratrol group only under the HC diet (P = 0.045). The relative abundance of 10 bacterial genera was affected by the three-way interaction of treatment, diet and time (P < 0.05). Resveratrol was partly converted to dihydroresveratrol after 24 h of fermentation, and its degradation could be associated with microbes belonging to the order Coriobacteriales. Our results suggest that multiple factors (e.g. diet and time) should be considered in animal experiments to test the effect of polyphenol or other plant extracts on rumen fermentation, methane emission and microbial composition.     

The effect of plant alkaloids on in vitro rumen microbial fermentation

Crude alkaloid extracts from green Italian Ryegrass differed from those extracted from the ensiled grass with particular respect to the perloline moiety. Free perloline and crude alkaloid extracts from both silage and grass inhibited the production of volatile fatty acids in the fermentation of glucose by rumen microbes. With silage as fermentation substrate alkaloid extracts from silage and from grass (0.200 mg/l) caused a decrease in both substrate utilization ( P< < 0.01) and proportion of methane in the gas phase ( P< < 0.01). Molar proportions of acetate were also significantly decreased ( P < 0.01) with a corresponding increase in the proportion of propionate ( P < 0.01). These effects were not observed when grass nuts were used as the fermentation substrate. The results suggest that it is not the alkaloids per se that affect rumen microbial metabolism.     

Effects of capric acid on rumen methanogenesis and biohydrogenation of linoleic and α-linolenic acid

Capric acid (C10:0), a medium chain fatty acid, was evaluated for its anti-methanogenic activity and its potential to modify the rumen biohydrogenation of linoleic (C18:2n-6) and α-linolenic acids (C18:3n-3). A standard dairy concentrate (0.5 g), supplemented with sunflower oil (10 mg) and linseed oil (10 mg) and increasing doses of capric acid (0, 10, 20 and 30 mg), was incubated with mixed rumen contents and buffer (1 : 4 v/v) for 24 h. The methane inhibitory effect of capric acid was more pronounced at the highest (30 mg) dose compared to the medium (20 mg) (-85% v. -34%), whereas the lower dose (10 mg) did not reduce rumen methanogenesis. A 23% decrease in total short-chain fatty acid (SCFA) production was observed, accompanied by shifts towards increased butyrate at 20 mg and increased propionate at 30 mg of capric acid (P < 0.001). Capric acid linearly decreased the extent of biohydrogenation of C18:2n-6 and C18:3n-3, by up to 60% and 86%, respectively. This reduction was partially due to a lower extent of lipolysis when capric acid was supplemented. Capric acid at 20 and 30 mg completely inhibited the production of C18:0 (P < 0.001), resulting in an accumulation of biohydrogenation intermediates, mainly C18:1t10 + t11 and C18:2t11c15. In contrast to effects on rumen fermentation (methane production and proportions of SCFA), 30 mg of capric acid did not induce major changes in rumen biohydrogenation as compared to the medium (20 mg) dose. This study revealed the dual action of capric acid, being inhibitory to both methane production and biohydrogenation of C18:2n-6 and C18:3n-3.     

Effect of tea saponin on rumen fermentation in vitro

The present study was conducted to investigate the effect of tea saponins (TS) on ruminal fermentation in vitro using gas syringes as incubators. The TS were added at levels of 0, 2, 4, 6 and 8 mg against 200 mg mixture of corn meal and grass meal (1/1, w/w) in rumen fluid. In vitro gas production (GP) was recorded and methane concentration was determined at 3, 6, 9, 12 and 24 h incubation. After 24 h, the incubation was stopped and the inoculants were determined for pH, ammonia-N, volatile fatty acids (VFAs), protozoa counts and microbial protein yield. The GP was increased with the increasing level of TS except 8 mg at 24 h, which kept little change from that of the control. Methane concentration was decreased at all levels of TS at each incubation time. At 24 h incubation, inclusion with 2, 4, 6 and 8 mg of TS decreased methane concentration by 13, 22, 25 and 26%, respectively. The pH of ruminal fluid was slightly lower at 4 and 6 mg TS, but all values were in the normal range. Ammonia-N concentrations decreased significantly (P < 0.01) when the TS were included. Concentrations of individual and total VFAs were not significantly effected by TS addition. The TS significantly inhibited the protozoa growth in ruminal fluid (P < 0.01). At 24 h incubation, protozoa counts were reduced by 19, 25, 45 and 79%, respectively at levels of 2, 4, 6 and 8 mg of TS compared to that in control. The microbial protein was enhanced with the TS addition except 2 mg level, and reached 1.92, 2.36 and 2.61 mg/mL with addition of 4, 6 and 8 mg TS, compared to 1.50 mg/mL in control. It is suggested that TS could modify the rumen fermentation and inhibit the release of methane and ammonia, which may be beneficial for improving nutrient utilization and animal growth.     

The effect of dietary concentrate and soya oil inclusion on microbial diversity in the rumen of cattle

Aims: Methane emissions from ruminants are a significant contributor to global greenhouse gas production. The aim of this study was to examine the effect of diet on microbial communities in the rumen of steers. Methods and Results: The effects of dietary alteration (50 : 50 vs 90 : 10 concentrate–forage ratio, and inclusion of soya oil) on methanogenic and bacterial communities in the rumen of steers were examined using molecular fingerprinting techniques (T‐RFLP and automated ribosomal intergenic spacer analysis) and real‐time PCR. Bacterial diversity was greatly affected by diet, whereas methanogen diversity was not. However, methanogen abundance was significantly reduced (P = 0·009) in high concentrate–forage diets and in the presence of soya oil (6%). In a parallel study, reduced methane emissions were observed with these diets. Conclusions: The greater effect of dietary alteration on bacterial community in the rumen compared with the methanogen community may reflect the impact of substrate availability on the rumen bacterial community. This resulted in altered rumen volatile fatty acid profiles and had a downstream effect on methanogen abundance, but not diversity. Significance and Impact of the Study: Understanding how rumen microbial communities contribute to methane production and how these microbes are influenced by diet is essential for the rational design of methane mitigation strategies from livestock.     

Microbial profiles, in vitro gas production and dry matter digestibility based on various ratios of roughage to concentrate

The study assessed the effects of different roughage to concentrate ratios on enteric methane production, rumen fermentation and microbial counts. These ratios were 80:20, 50:50, and 20:80 for diets 1, 2, and 3, respectively. No significant differences were observed in total gas production among diets; however, methane emissions increased (P?<?0.05) with increased roughage in diet. The pH was greater (P?<?0.05) in diet 1 compared to diets 2 and 3 (6.38 vs 6.17 and 6.07). In vitro dry matter digestibility increased with decreased roughage ratios (47.67, 61.67, 67.33 % for diets 1, 2 and 3, respectively). Similarly, total volatile fatty acids (mM/100 mL) also increased with decreased roughage ratios [diet 1 (5.38); diet 2 (6.30); diet 3 (7.37)]. Methanogen counts, total bacterial counts and protozoal counts were lower (P?<?0.05) in diet 3 compared to diet 1 and 2. However, total fungal counts were higher in diet 1 compared to diet 2 and 3. The results indicate that methane emission, enteric fermentation patterns, and change in methanogens population appear only with higher level of roughage. These findings are important for reducing methane without any impact on rumen performance.     

Effect of natural dolomites on the in vitro fermentation and rumen protozoan population using rumen fluid and fresh faeces inoculum from sheep

The objective of the study was to determine the effect of dolomites from five different sources upon the end products of in vitro fermentation (total gas, methane, total and individual fatty acids, hydrogen recovery) and protozoan population. Dolomites as natural products in the dose of 0.1 g were added to the fermentation bottles containing inoculum from sheep and substrates. Both rumen fluid (RF) and fresh faeces (FF) from sheep as the sources of inocula for in vitro fermentation were used. Meadow hay (MH) and barley grain (BG) were used as fermentation substrates and incubated with the buffered rumen fluid using an in vitro gas measuring technique in separate incubation during 72 h. Both inocula (RF and FF) and dolomites impact in vitro fermentation characteristics. The gas volume was significantly increased with dolomites with RF or FF, respectively, by 20% or 20–40% (MH) and by 10% or 10–30% (BG). The methane production was significantly decreased with dolomite additives with RF inocula by 15–32% (MH) and by 50–70% (BG). A significant effect of the dolomite additives on the rumen protozoan population was observed during fermentation of MH; the total protozoan concentration and the number of Entodinium spp. was decreased (P < 0.05). Populations of Isotrichids and large Entodiniomorphids were not influenced by experimental incubations. More studies are needed to optimize the combination of different diets with dolomite additives for practical feeding conditions.     

Effect of Chloral Hydrate on Methane and Propionic Acid in the Rumen

Methane production from pyruvate by mixed rumen bacteria in vitro was nearly totally inhibited by chloral hydrate (0.1 mumole/ml of incubation fluid). This effect was accompanied by an accumulation of gaseous hydrogen and an increase in propionic acid production. Infusion of chloral hydrate (4 g/day) into the rumen of a sheep produced the same effects. Evidence is presented for a direct toxic effect of chloral hydrate upon methane bacteria. Results are discussed in terms of fermentation balances.     

Effect of chitosans on in vitro rumen digestion and fermentation of maize silage

The gas in vitro technique was used to study the effects of six types of chitosans, each having different molecular weights and acetylation degrees, on rumen microbial fermentation. In a first trial, a separate concentration of 750 mg/l of culture fluid for each of the six chitosans (CHI1, CHI2, CHI3, CHI4, CHI5, and CHI6) was incubated for 24 h in diluted ruminal fluid with maize silage as the substrate. The ionophore antibiotic monensin (MON) was used as a positive control, and a negative control with no chitosan (CTR) was also included. Each treatment was tested in triplicate for three different periods. At the end of the trial, samples were collected to determine volatile fatty acid (VFA) and ammonia N concentrations, and pH and gas production values were recorded. Methane concentration was estimated stoichiometrically. In vitro true organic matter digestibility (IVOMD) and partitioning factor (PF, mg OM truly degraded/ml gas produced) were also calculated. In a second trial, a separate concentration of 750 mg/l of each of the six chitosans was incubated for 144 h in diluted ruminal fluid with maize silage as the substrate, to study the effects of these compounds on fermentation kinetics.All six chitosans decreased the IVOMD and PF values. Chitosan inclusion did not affect the fermentation of the substrate's soluble fraction, but did reduce the fermentation kinetics of the insoluble but fermentable fraction. However, only CHI5 and CHI6 decreased total VFA concentration. CHI3 and CHI6 decreased the molar proportion of acetate and increased the molar proportion of propionate, thus increasing the propionate-to-acetate ratio. Chitosan inclusion did not affect molar proportions of butyrate. With the exception of CHI2, the molar proportion of branch-chained VFA was lowered by all of the chitosan treatments. Most of the treatments also decreased methane production, also with the exception of CHI2.In conclusion, chitosan extracts may enable the manipulation of rumen microbial fermentation, but further research is required to elucidate the effect of chitosans on ruminal fermentation parameters in commercial diets as well as the adaptability of rumen microflora to these additives.     

Effect of carbon monoxide on fermentation of fiber, starch, and amino acids by mixed rumen microorganisms in vitro.

When 1 atm (101.3 kPa) of carbon monoxide was added to mixed rumen bacterial incubations containing timothy hay, methane production was inhibited by 88% without an increase in hydrogen. The molar ratio of propionate to acetate increased from 0.83 to 1.53, extracellular ammonia declined from 5.2 to 2.4 mM, and hemicellulose and cellulose digestions were inhibited by 40 and 27%, respectively. Even low levels of carbon monoxide (less than 0.1 atm [10.13 kPa]) significantly changed the products of fermentation. With starch, methane production was once again inhibited, but the magnitude of starch fermentation was unaffected. Decrease in acetate was accompanied by an equal molar increase in lactate. Ammonia production from the amino acid source, Trypticase, declined 20% as carbon monoxide was increased to 1.0 atm, and 93% of this decrease was explained by a selective inhibition of branched-chain amino acid fermentation.     

Effect of carbon monoxide on fermentation of fiber, starch, and amino acids by mixed rumen microorganisms in vitro

When 1 atm (101.3 kPa) of carbon monoxide was added to mixed rumen bacterial incubations containing timothy hay, methane production was inhibited by 88% without an increase in hydrogen. The molar ratio of propionate to acetate increased from 0.83 to 1.53, extracellular ammonia declined from 5.2 to 2.4 mM, and hemicellulose and cellulose digestions were inhibited by 40 and 27%, respectively. Even low levels of carbon monoxide (less than 0.1 atm [10.13 kPa]) significantly changed the products of fermentation. With starch, methane production was once again inhibited, but the magnitude of starch fermentation was unaffected. Decrease in acetate was accompanied by an equal molar increase in lactate. Ammonia production from the amino acid source, Trypticase, declined 20% as carbon monoxide was increased to 1.0 atm, and 93% of this decrease was explained by a selective inhibition of branched-chain amino acid fermentation.     

Effect of tea saponin on methanogenesis,microbial community structure and expression of mcrA gene,in cultures of rumen micro‐organisms

Aims: To determine the in‐vitro effect and mode of action of tea saponin on the rumen microbial community and methane production. Methods and Results: Saponin extracted from tea seeds was added to (1) an in‐vitro fermentation inoculated with rumen fluid and (2) a pure culture of Methanobrevibacter ruminantium. Methane production and expression of the methyl coenzyme‐M reductase subunit A (mcrA) were monitored in both cultures. Abundance of methanogens, protozoa, rumen fungi and cellulolytic bacteria were quantified using real‐time PCR, and bacterial diversity was observed using denaturing gradient gel electrophoresis. Addition of tea saponin significantly reduced methane production and mcrA gene expression in the ruminal fermentation but not with the pure culture of M. ruminantium. The abundance of protozoa and fungi were significantly decreased 50% and 79% respectively but methanogen numbers were not affected, and Fibrobacter succinogenes increased by 41%. Bacterial diversity was similar in cultures with or without tea saponin. Conclusions: Tea saponin appeared to reduce methane production by inhibiting protozoa and presumably lowering methanogenic activity of protozoal‐associated methanogens. Significance and Impact of the Study: Tea saponin may be useful as a supplement to indirectly inhibit methane production in ruminants without a deleterious effect on rumen function.     

Effects of wheat dried distillers' grains with solubles and cinnamaldehyde on in vitro fermentation and protein degradation using the Rusitec technique

This study was conducted to evaluate the effect of wheat dried distillers' grains with solubles (DDGS) and cinnamaldehyde (CIN) on in vitro fermentation and microbial profiles using the rumen simulation technique. The control substrate (10% barley silage, 85% barley grain and 5% supplement, on dry matter basis) and the wheat DDGS substrate (30% wheat DDGS replaced an equal portion of barley grain) were combined with 0 and 300 mg CIN/l of culture fluid. The inclusion of DDGS increased (p < 0.05) the concentration of volatile fatty acids (VFA) and the molar proportion of acetate and propionate. Dry matter disappearance (p = 0.03) and production of bacterial protein (p < 0.01) were greater, whereas the disappearances of crude protein (CP) and neutral detergent fibre were less (p < 0.01) for the DDGS than for the control substrate. With addition of CIN, concentration of total VFA decreased and fermentation pattern changed to greater acetate and less propionate proportions (p < 0.01). The CIN reduced (p < 0.01) methane production and CP degradability. The copy numbers of Fibrobacter, Prevotella and Archaea were not affected by DDGS but were reduced (p < 0.05) by CIN. The results indicate that replacing barley grain by DDGS increased nutrient fermentability and potentially increase protein flows to the intestine. Supplementation of high-grain substrates with CIN reduced methane production and potentially increased the true protein reaching the small intestine; however, overall reduction of feed fermentation may lower the feeding value of a high-grain diet.