体外添加不同水平的亚麻籽油对气体产量、瘤胃发酵及脂肪酸组分的影响

利用瘤胃体外产气法研究在羊草底物条件下添加不同水平的亚麻籽油(LSO)对气体产量、瘤胃发酵和脂肪酸组分的影响。LSO添加水平分别为底物干物质的5%和10%,体外培养持续48 h。在12、24和48 h时测量总气体产量、甲烷及氢气产量,培养结束后测定发酵指标和发酵液中脂肪酸成分。结果表明,LSO显著降低了产气量和甲烷产量,提高了氢气产量;添加LSO显著提高了总挥发性脂肪酸含量、丙酸和丁酸的比例,还显著降低了发酵液pH和氨氮浓度;同时,添加LSO提高了发酵液中对人体健康有益的共轭亚油酸以及其他不饱和脂肪酸的比例。这些结果表明,富含十八碳不饱和脂肪酸的LSO可以在粗饲料条件下抑制甲烷生成,改善瘤胃发酵,增加了多不饱和脂肪酸的含量,而且抑制甲烷生成及改善瘤胃发酵的效果与添加剂量有关。     

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。     

乳酸链球菌素对瘤胃体外发酵、甲烷生成及功能菌群数量的影响北大核心CSCD

【目的】旨在通过体外静态模拟瘤胃发酵法研究乳酸链球菌素(NI)对瘤胃发酵、甲烷生成及功能菌群数量的影响。【方法】以不添加任何添加剂处理做阴性对照(NC),以莫能菌素(MON,5μmol/L)做阳性对照,试验组NI添加水平分别为3(NI-3)、9(NI-9)和27 mg/100 m L(NI-27),每个处理4个重复,分别于培养后的0、3、6、9、12、24 h测定产气量和甲烷产量。培养24 h后,采集发酵液样品,用于发酵参数和菌群数量的测定。【结果】与NC组相比,添加NI和MON均能显著降低产气量和甲烷产量(P<0.05);添加NI对pH值、干物质消失率(DMD)和有机物消失率(OMD)无显著影响(P>0.05);NI-9处理组与NC组相比氨态氮浓度显著降低(P<0.05),而NI-3和NI-27组氨氮浓度没有显著变化(P>0.05);相比而言,MON处理组DMD、OMD和氨氮浓度与NC组相比均显著降低(P<0.05),而pH值与其他各处理组相比没有差异(P>0.05);与NC组相比,NI各处理组和MON组乙酸浓度及乙丙比均显著降低(P<0.05),丙酸浓度显著提高(P<0.05)。功能菌方面,qPCR结果显示添加NI和MON对总菌和拟杆菌门数量均无显著影响(P>0.05);与NC相比,添加NI对原虫、甲烷菌、真菌和厚壁菌门数量均无显著影响(P>0.05),而MON组原虫、甲烷菌、真菌和厚壁菌门数量显著降低(P<0.05);NI和MON处理均显著提高了硫还原菌和C.aminophilum数量(P<0.05),但C.sticklandii数量不受影响(P>0.05)。【结论】添加适宜浓度的NI可降低瘤胃甲烷与氨的生成,但并不影响饲料消化,这种发酵模式的改变可能与瘤胃功能菌群数量与多样性的变化密切相关。     

氮添加对沙质草地氨挥发及硝态氮淋溶的影响

采用密闭室法和离子交换树脂袋法,研究了科尔沁沙质草地不同处理(水添加、氮添加、水氮添加)氧挥发的损失量和硝态氮的淋溶量.结果表明:氮添加处理和水氮添加处理显著促进了氨挥发(P＜0.05),最大氨挥发速率显著高于对照;氮添加处理和水氮添加处理的氨挥发累积量为111.80和148.64 mg·m-2,分别占氮添加量的1.1％和1.5％;水氮同时添加条件下,氨挥发累计量显著高于氨添加处理(P＜0.05),水添加处理和对照相比没有显著差异(P＞0.05);水氮添加处理显著增加了土壤深度20 cm处的硝态氮淋溶量(P＜0.05),氮添加处理和水氮添加处理的硝态氮淋溶量分别是对照的1.96和4.22倍,然而在土壤深度40 cm处各处理硝态氮淋溶量差异不显著(P＞0.05);可见,氮添加和水氮添加均促进了土壤的氧挥发,对硝态氮的淋溶没有显著影响.     

玉米低聚糖对双歧杆菌增殖与发酵的影响

目的研究玉米低聚糖对双歧杆菌增殖和发酵的影响。方法试验I组以乳糖替代正常TPY培养基中葡萄糖作为碳源,试验II组以玉米低聚糖替代TPY培养基中的葡萄糖作为唯一碳源,分别在接种培养0、12、24、36、48和72h对两组双歧杆菌活菌数量、培养液中还原糖含量和培养液pH值进行测定。同时以不同剂量玉米低聚糖饲喂小鼠,分析对小鼠粪便中双歧杆菌数量的影响。结果培养72h后,试验II组双歧杆菌活菌数显著高于试验I组(t=5.832,P0.05)。试验II组培养液中葡萄糖含量在12、24、36、48和72h时均较试验I组显著偏高(P0.05)。试验II组培养液中pH在24h之后一直显著低于试验I组(P0.05)。试验I组、II组小鼠粪便中双歧杆菌数量显著高于饲喂前(t=20.109、22.982,P0.05);试验III组小鼠粪便中双歧杆菌数量较饲喂前显著降低(t=4.692,P0.05)。结论玉米低聚糖能够显著促进双歧杆菌体外增殖,增强发酵,并能提高小鼠肠道中双歧杆菌的数量。     

不同氮源对蛋白核小球藻生长、色素和中性脂肪积累的影响

单细胞微藻在生长发育过程中,所积累的中性脂肪具有潜在的生物燃料价值。不同氮源对藻类的生长具有显著影响。研究了氨态氮、尿素氮和硝酸态氮对蛋白核小球藻生长、色素和中性脂肪积累的影响。结果显示,不同氮源对培养液pH有显著影响,以氨态氮为氮源导致培养液pH降低,而硝酸态氮导致培养液pH升高,培养液pH的波动可被添加的Hepes所稳定,并促进以氨态氮为氮源的蛋白核小球藻的生长。尿素氮对蛋白核小球藻生长、色素积累的效果优于氨态氮和硝酸态氮,硝酸态氮在中性脂肪积累上优于尿素氮和氨态氮,添加Hepes对氮饥饿后蛋白核小球藻的中性脂肪积累无显著影响。     

不同碳水化合物对孤独症患儿肠道菌群 体外发酵产生短链脂肪酸的影响

目的探究孤独症谱系障碍(autism spectrum disorder,ASD)患儿与健康儿童的肠道菌群利用不同碳水化合物产生短链脂肪酸(short-chain fatty acids,SCFAs)的差异。方法前瞻性病例对照研究。选择2016年12月至2017年10月解放军总医院儿科门诊的15例ASD患儿为研究对象,并匹配15名健康儿童为对照组;收集研究对象粪便,稀释成10%悬浊液,然后分别接种到以乳果糖(LAU)、乳糖(LAT)、棉籽糖(RAF)、低聚半乳糖(GOS)、低聚异麦芽糖(IMO)和低聚甘露糖(MOS)为单碳源的肠道微生态小型模拟发酵系统中批量发酵24 h,检测SCFAs浓度、底物降解率和产气气压。结果 ASD组患儿粪便SCFAs浓度与对照组差异无统计学意义,在YCFA(无碳源对照培养基,蛋白发酵为主)培养基发酵后总SCFAs、乙酸和丙酸均低于对照组,差异有统计学意义(Z=-2.509、-2.509、-3.007,P=0.011、0.011、0.002);在添加LAT、RAF、GOS、IMO和MOS的培养基发酵后总SCFAs浓度显著高于对照组,差异有统计学意义(Z=2.385、2.344、2.675、2.344、2.302,P=0.016、0.019、0.007、0.019、0.021),而含LAU的培养基发酵后,两组研究对象总SCFAs浓度比较差异无统计学意义。结论 ASD患儿肠道菌群利用蛋白发酵产SCFAs能力显著低于健康对照,利用碳水化合物产SCFAs能力显著高于健康对照。6种发酵底物中,乳果糖是最适合ASD患儿的碳水化合物,有改善ASD患儿肠道菌群产SCFAs的潜力。     

毕赤酵母工程菌高密度发酵中氨态氮含量的测定

首次尝试将钠氏法应用于毕赤酵母高密度发酵中,并与靛酚蓝检测法进行了比较,证实钠氏法在0~10 mg/L的范围内,相关性好(r2=0.996 5),精确度(RSD=2.14%~5.32%)和精密度(Prec ision=97%~105%)高,更适合于毕赤酵母发酵中氨态氮含量的检测。并对其检测条件进行优化,确定检测波长为400 nm,最佳的显色反应为10 min。该方法用于毕赤酵母高密度发酵表达重组人血清白蛋白胸腺肽的结果表明,在发酵液氨基氮含量低于1.5 mg/kg,重组目的蛋白的表达出现了明显的降解,改善并控制发酵液中氨态氮的含量后,可以明显控制目的蛋白的降解,提高产品的产率。结果证实该方法用于发酵液中氨态氮的检测时,准确可靠,切实可行。     

一株瘤胃源乳酸利用菌的分离鉴定及其体外代谢特性

【目的】从饲喂高精料的本地山羊瘤胃内分离到一株利用乳酸并能产生大量丙酸的菌株L9,并进一步研究了该菌在调控瘤胃微生物发酵中的作用。【方法】采用厌氧培养技术,结合形态、生理生化特性和16SrRNA基因序列分析结果。【结果】该菌株被鉴定为反刍兽新月形单胞菌（Selenomonas ruminantium）。该菌株体外代谢特性研究表明,L9可利用乳酸作为唯一碳源,该菌在24h内可对90mmol／L的乳酸完全降解。体外摸拟瘤胃急性酸中毒的发酵试验结果表明,以淀粉为底物时,与对照组相比,添加菌株L9可显著降低瘤胃微生物体外培养体系中乳酸浓度,提高pH值,提高总挥发性脂肪酸和丙酸浓度,并显著降低乙酸与丙酸的浓度比（P〈0．05）。【结论】结果显示,菌株L9是一株可代谢乳酸,促进丙酸生成,提高总挥发性脂肪酸浓度的有益瘤胃细菌。     

载锌凹凸棒石黏土对瘤胃体外发酵细菌多样性的影响

【目的】研究载锌凹凸棒石黏土对瘤胃体外发酵细菌多样性的影响。【方法】本试验采用离子交换法制备载锌凹凸棒石黏土,利用16S rDNA测序技术分析了载锌凹凸棒石黏土对奶牛瘤胃体外发酵细菌菌群和多样性的影响。【结果】研究共获得1490959个有效序列和87662个OTUs。测序结果表明,与对照组相比,试验Ⅳ组中的细菌多样性在体外发酵24 h时提高,试验Ⅳ组中的细菌丰度在体外发酵48 h时提高。细菌菌群组成分析表明,60个样本中的优势菌门主要是厚壁菌门、拟杆菌门、变形菌门和黏胶球形菌门。与对照组相比,各试验组的厚壁菌门在体外发酵24 h和48 h时均显著增加(P0.05),试验Ⅳ组中拟杆菌门在发酵48 h时显著降低(P0.05);60个样本中共获得124个细菌菌属,其中对照组与试验组中普氏菌属含量均没有显著变化(P0.05)。在体外发酵48 h时,试验Ⅳ组中密螺旋体属含量与对照组相比显著增加(P0.05),而食物谷菌属和假丁酸弧菌属含量与对照组相比均显著降低(P0.05)。【结论】载锌凹凸棒石黏土对奶牛瘤胃体外发酵中细菌多样性产生一定影响,其影响随发酵时间和添加剂量而不同。     

产木聚糖酶厌氧真菌菌株筛选及产酶培养条件研究*

从12株分离自反刍动物瘤胃及粪样的厌氧真菌中筛选到一株木聚糖酶高产菌,编号为A4,初步鉴定为Neocallimastix属菌。以稻草秸、玉米秸、花生秸、滤纸片段为发酵底物,经39℃厌氧培养,A4菌产生的木聚糖酶活分别为14.31U/mL、11.39U/mL、6.99U/mL和13.38U/mL。对A4菌产生木聚糖酶的条件进行优化,结果发现,培养基中无细胞瘤胃液浓度对A4菌产生的木聚糖酶活无显著影响;但酵母膏浓度从1.0g/L降至0.5g/L后,A4菌产生的木聚糖酶活显著下降(P<0.05)。     

Evaluation of native potential probiotic bacteria using an in vitro ruminal fermentation system

Rumen microbiota provides an important source of protein to grazing animals and produces volatile fatty acids (VFA), the main energy source for ruminants generated by fibre fermentation. Probiotics can be used to modulate rumen fermentation, and native microbiota is a source of potentially useful microorganisms. In this work, ruminal bacterial strains were isolated and subsequently identified, and their potential to modify fermentation patterns with wheat straw, microcrystalline cellulose and oat xylan as substrates was assessed by in vitro gas production and VFA fermentation patterns. Four of the isolates were identified as Pseudobutyrivibrio ruminis and two corresponded to new members of the Lachnospiraceae family. The addition of one P. ruminis (strain 50C) and one Lachnospiraceae (strain 21C) to the fermentation system which used wheat straw as the substrate significantly increased total VFA concentration without altering the total gas produced in one case and showed a decrease in total gas production in the other. All bacterial strains induced higher butyric acid concentrations with the three substrates (up to 31 mM in the case of Lachnospiraceae 21C incubated with oat xylan and 25 mM in microcrystalline cellulose fermenters to which P. ruminis 50C had been added) compared to the control, which had concentrations of <1 mM. Analysis of the fermentation products suggested that the addition of probiotics to the fermentation system had the potential to induce metabolic shifts that would result in better energy yields. These results show that native bacteria have promising features as fermentation modulators, thereby justifying further research to assess their use as probiotics for ruminants.     

Effect of anaerobic fungi on in vitro feed digestion by mixed rumen microflora of buffalo

Five strains of anaerobic fungi isolated from the faeces of wild (hog deer, Cervus porcinus; blackbuck, Antelope cervicapra; spotted deer, Axis axis; nilgai, Baselophus tragocamelus) and rumen liquor of domestic (sheep, Ovies aries) ruminants showing high fibrolytic enzyme producing ability were added to mixed rumen microflora of buffalo to study their effect on the digestibility of lignocellulosic feed (wheat straw and wheat bran in the ratio of 80:20), enzyme production and fermentation end products in in vitro conditions. Among the 5 isolates studied, FNG5 (isolated from nilgai) showed the highest stimulating effect on apparent digestibility (35.31 +/- 1.61% vs. 28.61 +/- 1.55%; P < 0.05), true digestibility (43.64 +/- 1.73% vs. 35.37 +/- 1.65%; P < 0.01), neutral detergent fiber digestibility (29.30 +/- 2.58% vs. 18.47 +/- 2.12; P < 0.01) of feed 24 h after inoculation compared to the control group. The production of carboxymethyl cellulase, xylanase, acetyl esterase and beta-glucosidase was significantly (P < 0.05) higher in the FNG5 inoculated incubation medium. There was no improvement in the digestibility and enzyme production on the addition of the other 4 isolates. Total volatile fatty acid levels as well as the concentration of acetate, propionate, isobutyrate and valerate were significantly higher in the FNG5 added group as compared to the control group. The fungal isolate FNG5 from nilgai, a wild ruminant, was found to be superior to the other isolates tested and appears to have a potential to be used as a feed additive for improving fiber degradation in domestic ruminants.     

The stimulatory effect of the organic sulfur supplement, mercaptopropane sulfonic acid on cellulolytic rumen microorganisms and microbial protein synthesis in cattle fed low sulfur roughages

Two metabolism trials (experiments 1 and 2) were conducted to examine the effect of the organic S compound, sodium 3-mercapto-1-propane sulfonic acid (MPS) on feed intake, fiber digestibility, rumen fermentation and abundance of cellulolytic rumen microorganisms in cattle fed low S (<0.11%) roughages. Urea was provided in all treatments to compensate for the N deficiency (<0.6%) in the roughages. In experiment 1, steers (333 ± 9.5 kg liveweight) were fed Angleton grass (Dicanthium aristatum) supplemented with S in equivalent amounts as either MPS (6.0 g/day) or sodium sulfate (9.56 g/day). Supplementation of Angelton grass with either sulfate or MPS resulted in an apparent increase in flow of rumen microbial protein from the rumen. Sulfur supplementation did not significantly change whole tract dry matter digestibility or intake, even though sulfate and MPS supplementation was associated with an increase in the relative abundance of the fibrolytic bacteria Fibrobacter succinogenes and anaerobic rumen fungi. Ruminal sulfide levels were significantly higher in the sulfate treatment, which indicated that the bioavailability of the two S atoms in the MPS molecule may be low in the rumen. Based on this observation, experiment 2 was conducted in which twice the amount of S was provided in the form of MPS (8.0 g/day) compared with sodium sulfate (6.6 g/day) to heifers (275 ± 9 kg liveweight) fed rice straw. Supplementation with MPS compared with sulfate in experiment 2 resulted in an increase in concentration of total volatile fatty acids, and ammonia utilization without a change in feed intake or whole tract fiber digestibility even though S and N were above requirement for growing cattle in both these treatment groups. In conclusion, supplementation of an S deficient low-quality roughage diet with either MPS or sodium sulfate, in conjunction with urea N, improved rumen fermentation, which was reflected in an increase in urinary purine excretion. However, MPS appeared to have a greater effect on stimulating short-chain fatty acid production and ammonia utilization when provided at higher concentrations than sulfate. Thus, the metabolism of MPS in the rumen needs to be investigated further in comparison with inorganic forms of S as it may prove to be more effective in stimulating fermentation of roughage diets.     

Effect of three strains of Pleurotus tuber-regium (Fr.) Sing. on chemical composition and rumen fermentation of wheat straw

This study was conducted to investigate changes in in vitro dry matter digestibility (IVDMD) and cell wall constituent degradation in wheat straw treated with 3 strains of the fungus Pleurotus tuber-regium (PT). The incubation of wheat straw for 30 days at 28 degrees C improved IVDMD from 30.3% (UWS-untreated wheat straw) to 47.1% for strain PT1, to 48.5% for PT4, and was unchanged IVDMD-29.9% -for PT5. The growth of fungi was accompanied by the dry matter loss of wheat straw: 31.5% for PT1, 20.9% for PT4, and 4.8% for PT5. Fungal treatment was characterized by increased crude protein and ash contents (%) in all fungi-treated straws and reduced hemicellulose and lignin content. It is evident that enzymes of all 3 PT strains preferentially degraded hemicellulose and lignin over cellulose. Wheat straw treated with PT1 (TWS-PT1), PT4 (TWS-PT4), and PT5 (TWS-PT5) and barley (80% : 20%) were used as the experimental diets at the fermentation in the artificial rumen. UWS with barley (80% : 20%) served as the control diet. The fermentation of experimental diets was accompanied with increased IVDMD and a very low degree of hemicellulose degradation. Total gas and methane productions were similar in all diets. Moreover, total volatile fatty acid (VFA) production (mmol day(-1)), mol % of acetate, propionate, butyrate, isobutyrate, and isovalerate were not influenced during the fermentation of experimental diets. From the stoichiometric relations, production, utilization, and recovery of metabolic hydrogen and organic matter fermented were unchanged. Only the recovery of metabolic hydrogen in TWS-PT5 was significantly increased in comparison to control diet. Total microbial production showed the tendency of lower values in experimental diets, and it was accompanied with a significant decrease of ammonia nitrogen (mg L(-1)). Finally the results showed that the strains of Pleurotus tuber-regium can improve the quality of wheat straw, but the loss of dry matter (DM) (mainly hemicellulose) limits the effective utilization of fungi-treated straw in ruminant digestion.     

Investigation on the biodegradability of mycotoxins nivalenol (NIV) and deoxynivalenol (DON) in a rusitec fermentor and their monitoring by HPLC/MS

Biodegradation of two B-trichothecenes nivalenol (NIV) and deoxynivalenol (DON) have been studied in a RUSITEC (rumen simulation technique) system. The fermentation studies were carried out in vessels containing the rumen fluid. To reach steady state an adaptation period of one week was carried out. The mycotoxin standards were then added into the fermentor in a concentration of 1ppm NIV and 2ppm DON. The kinetics of NIV and DON biodegradability during the fermentation process were monitored by using a rapid HPLC method combined with a mass spectrometer and an atmospheric pressure chemical ionisation (APCI^-) interface. Also the effect of mycotoxin addition on different parameters such as ammonia production, pH, gas production and volatile fatty acids have been studied.     

Different endosperm structures in wheat and corn affected in vitro rumen fermentation and nitrogen utilization of rice straw-based diet

Starchy grain is usually supplemented to diets containing low-quality forage to provide sufficient energy for ruminant animals. Ruminal degradation of grain starch mainly depends on the hydrolysis of the endosperm, which may be variable among grain sources. This study was conducted to investigate the influence of endosperm structure of wheat and corn on in vitro rumen fermentation and nitrogen (N) utilization of rice straw. The 3×4 factorial design included three ratios of concentrate to forage (35:65, 50:50 and 65:35) and four ratios of wheat to corn starch (20:80, 40:60, 60:40 and 80:20). The endosperm structure was detected by scanning electronic microscopy and a confocal laser scanning microscopic. An in vitro gas test was performed to evaluate the rumen fermentation characteristics and N utilization. Starch granules were embedded in the starch–protein matrix in corn, but more granules were separated from the matrix in the wheat endosperm. With the increasing ratio of wheat, rate and extent of gas production, total volatile fatty acids, and ammonia N increased linearly (P<0.01), but microbial protein concentration decreased (quadratic, P<0.01), with the maximum value at a ratio of 40% wheat. The efficiency of N utilization decreased linearly (P<0.01). Rumen fermentation and N utilization were significantly affected by the concentrate-to-forage ratio (P<0.01). Significant interactions between the concentrate-to-forage ratio and the wheat-to-corn ratio were detected in total volatile fatty acids and the efficiency of N utilization (P<0.01). In summary, the starch–protein matrix and starch granules in the wheat and corn endosperm mixture play an important role in the regulation of rumen fermentation and N utilization under low-quality forage.     

乙醇对瘤胃液接种稻秸的体外发酵产物及细菌群落结构的影响

旨在研究乙醇对山羊瘤胃液与水稻秸秆厌氧共培养的影响。利用频繁传代的体外发酵技术和高通量测序方法,分析了短链脂肪酸(SCFA)产量和细菌群落的变化。结果表明,经体外培养传代8次的稻秸发酵液的总短链脂肪酸产量显著高于瘤胃液(P<0.01);与未添加乙醇的稻秸发酵液相比,添加乙醇显著提高了乙酸、戊酸和己酸的比例,降低了丙酸和丁酸的比例(P<0.01),总SCFA产量及异丁酸和异戊酸比例无显著差异。与瘤胃液相比,稻秸发酵液的拟杆菌门(Bacteroidetes)相对丰度下降,厚壁菌门(Firmicutes)相对丰度升高(P<0.05),且添加乙醇显著提高了厚壁菌门和放线菌门(Actinobacteria)的相对丰度(P<0.05);添加乙醇使双歧杆菌属(Bifidobacterium)、未定性的毛螺菌属(unidentified Lachnospiraceae)、产琥珀酸菌属(Succiniclasticum)、脱硫弧菌属(Desulfovibrio)和未定性的梭菌属(unidentified Clostridiales)的相对丰度显著升高(P<0.05)。乙醇使稻秸发酵液的显著性差异物种(Biomarker)增加;稻秸发酵液与瘤胃液亲缘关系较近,而添加乙醇显著改变了细菌区系;短链脂肪酸比例在稻秸发酵液细菌群落多样性中具有重要作用。研究表明,体外频繁传代和添加乙醇可以提高稻秸发酵液的乙酸、戊酸和己酸产量,乙醇改变了稻秸发酵液的细菌群落结构。     

The effect of ammonia treatment on the solubilization of straw and the growth of cellulolytic rumen bacteria

Pre-treatment of straw with anhydrous ammonia increased its susceptibility to solubilization by the predominant cellulolytic bacteria from the rumen, Bacteroides succinogenes, Ruminococcus albus and R. flavefaciens. Ammonia treatment also increased the production of microbial protein and fermentation products by all three species. Scanning electron microscope observations of straw during digestion suggested that the attack of straw by these bacteria was accompanied by the formation of substantial numbers of adherent microcolonies.     

Is the anthelmintic effect of heather supplementation to grazing goats always accompanied by anti-nutritional effects?

To test the hypothesis that the beneficial anthelmintic effect of consuming moderate amounts of tannins may not always be accompanied by anti-nutritional effects in goats, two experiments were conducted. In the first, 48 Cashmere goats were randomly assigned to two treatments: supplementation with tannin-containing heather (6.4% total tannins) and non-supplementation. All goats grazed continuously from May to September under farm conditions in a mountainous area of northern Spain. The mean percentage of heather incorporated into the diet of the supplemented animals was 29.1%. Supplementation reduced the mean number of nematode eggs in faeces (P < 0.001) and the goat mortality rate (P < 0.05). The rumen ammonia concentration was markedly reduced in the goats receiving the heather supplement (160 v. 209 mg/l; P < 0.01), while volatile fatty acid (VFA) concentrations were significantly greater (63.0 v. 53.6 mmol total VFA/l; P < 0.05). The heather-supplemented goats also showed a lower loss of live weight (P < 0.01) and body condition score (P < 0.001). In the second experiment, batch cultures of rumen microorganisms with rumen fluid from nine goats whose diet included 29% heather - or not, were used to incubate three substrates (pasture, pasture + heather and pasture + heather + polyethylene glycol) to investigate in vitro ruminal fermentation. Differences (P < 0.01) among substrates were observed in terms of dry matter disappearance (DMD), in vitro true substrate digestibility (ivTSD), gas production and ammonia concentration, the greatest values always associated with the pasture substrate. Cultures involving rumen inoculum derived from goats receiving the heather-containing diet showed slightly lower DMD (46.9 v. 48.5 g/100 g; P < 0.05), ivTSD (64.6 v. 65.9 g/100 g; P < 0.10) and gas production (105 v. 118 ml/g; P < 0.001) values, but much greater total VFA concentrations (48.5 v. 39.3 mmol/l; P < 0.05), and suggest that the efficiency of ruminal fermentation in these animals was probably improved. Together, the results support the absence of a clear nutritional cost counteracting the beneficial anthelmintic effect of supplementing the diet of grazing goats with tannin-containing heather.