过瘤胃保护蛋氨酸稳定性及其评定方法的研究

本研究应用双外流连续培养系统和瘤胃尼龙袋法检验动物油包被蛋氨酸在瘤胃中的稳定性。根据动物油添加比例不同(分别添加20%、30%和40%),保护性蛋氨酸分为过瘤胃保护蛋氨酸I(RPMet-I)、过瘤胃保护蛋氨酸II(RPMet-II)和过瘤胃保护蛋氨酸III(RPMet-III)。试验结果表明:与未包被蛋氨酸相比,动物油包被蛋氨酸在瘤胃中的释放率显著降低(P<0.05);动物油添加比例不同对于过瘤胃保护蛋氨酸的稳定性影响显著(P<0.05)。不同形式保护性蛋氨酸在双外流连续培养系统中的降解趋势与在瘤胃中的降解趋势相似,且应用双外流连续培养系统测定各个时间点保护性蛋氨酸的释放率简单、稳定,与瘤胃尼龙袋法相比各个时间点的释放率均存在强相关回归关系(n=5,P<0.01),因此该系统适宜于评定保护性氨基酸的稳定性。     

双外流连续培养系统模拟瘤胃消化

近一个多世纪以来 ,人们一直在寻求能替代体内法的研究方法 ,来研究瘤胃的消化代谢。从两级离体消化法 (Ｔｉｌｌｅｒｙ和Ｔｅｒｒｙ ,1 963)到产气量法 (Ｍｅｎｋｅ等 ,1 979)以及酶解法等 ,都只能做到批次培养而不能模拟瘤胃的动态消化。而连续培养系统的出现 ,解决了这方面的问题 ,使人们能更加精确地模拟瘤胃的消化、代谢。1　连续培养系统的类型自从出现连续培养系统起 ,经历了从单外流到双外流的发展历程。单外流是指食糜中的液相和固相 ,是以相同的速度外流。由于正常瘤胃发酵时 ,固相和液相的外流速度是不同的 ,液相 ( 4%～ 1 0 % /…     

应用双外流连续培养法研究肉桂醛和大蒜油对瘤胃微生物发酵的影响

本试验研究肉桂醛（CIN）和大蒜油（GAR）对瘤胃微生物发酵的影响。应用双外流连续培养系统的8个接种瘤胃液的连续培养发酵罐进行试验。瘤胃液供体牛为小母牛，日粮精粗比为50：50（17．6％CP，28．0％NDF），粗饲料为苜蓿。负对照组不做处理，正对照组添加1．25mg／L（MON）和12．5mg／L（MON10）的携带离子型莫能霉素；试验组添加31．2mg／L（CIN）和312mg／L（CINl0）的CIN，31．2mg／LGAR（GAR）和312mg／L（GARl0）的GAR（Alllum sativa）。试验结果表明，添加MON10组引起瘤胃微生物发酵模式的改变（降低了纤维消化率、氨氮浓度和乙、丁酸比例，提高了丙酸比例，有增加小肽氨基酸氮浓度的趋势）。     

在连续培养条件下饲料中纤维成分和颗粒大小对瘤胃微生物中氨基酸流通率的影响

使用8个双外流连续培养发酵罐进行10d实验，研究饲料中纤维含量和饲料颗粒对瘤胃发酵、营养物质流通率和氨基酸流通率的影响。处理组采用2x2的设计方法。所用饲料分别为高纤维含量（HF）饲料和低纤维含量（LF）饲料。高纤维含量日粮为67％苜蓿干草，纤维浓度为33％；     

外流速率实测与参考对羊常用饲料瘤胃有效降解率的影响

本研究旨在测定半细毛羊6种常用饲料瘤胃外流速率,并分析外流速率实测值与普遍采用的参考值对所测饲料瘤胃有效降解率的影响。选用16只3周岁、健康状况良好、体重63～65 kg的云南半细毛羊公羊作为试验动物,其中4只装有永久性瘤胃瘘管。4只瘘管羊只用来测定铬标记饲料干物质回收率,12只非瘘管羊用来测定瘤胃外流速率。待测瘤胃外流速率的6种饲料分别为豆粕、菜籽粕、玉米、鸭茅、大豆秸秆和小麦秸秆。结果表明:1)采食豆粕、菜籽粕、玉米3种铬标记精饲料后粪中铬含量达到高峰的时间为24～28 h,采食鸭茅、大豆秸秆、小麦秸秆3种铬标记粗饲料后则为24～36 h。2)不同饲料之间瘤胃外流速率有差异,豆粕、菜籽粕、玉米、鸭茅、大豆秸秆、小麦秸秆的瘤胃外流速率分别为7.30%/h、7.49%/h、6.84%/h、5.02%/h、5.59%/h、3.97%/h。3)基于外流速率实测值与参考值计算所得6种饲料干物质、有机物和粗蛋白质有效降解率差异较大,且采用实测值计算所得数值全部低于采用参考值计算所得数值。由此可见,基于外流速率实测值计算所得瘤胃有效降解率与基于外流速率参考值计算所得瘤胃有效降解率差异较大,在利用瘤胃尼龙袋法测定饲料瘤胃有效降解率的实际研究工作中,建议对饲料瘤胃外流速率进行实测。     

氨化处理对新银合欢的营养成分和人工瘤胃发酵特性的影响

试验对新银合欢枝叶、种子和荚的常规营养成分和含羞草素含量进行了测定;以及氨化对新银合欢养分和含羞草素含量的影响。采用2×2因子试验设计(处理1为氨化新银合欢;处理2为氨化新银合欢+玉米;处理3为未氨化新银合欢;处理4为未氨化新银合欢+玉米),结合双外流连续培养系统研究了新银合欢的发酵特点。结果表明:新银合欢枝叶、种子和荚粗蛋白含量分别为27.33%、27.37%、6.02%,粗纤维含量分别为16.9%、12.85%、47.59%,含羞草素含量分别为2.75%、4.5%、0.22%。新银合欢枝叶氨化后粗蛋白含量显著升高(P<0.05),含羞草素、粗脂肪含量极显著降低(P<0.01),中性洗涤纤维含量显著降低(P<0.05)。氨化处理新银合欢对瘤胃pH有明显影响,提高了氨释放速度;添加玉米共同发酵有利于维持瘤胃稳定和提高对氨氮的利用效率。     

不同有机物进食量和外流速度对瘤胃发酵及微生物蛋白合成效率的影响

采用2×2随机因子试验设计研究持续动态瘤胃模拟装置(RSI-Ⅱ)不同有机物进食量(OMI)(27．67g、36．74g、46．00g)和瘤胃外流速度(0．02/h、0．035/h、0．05/h)对稻草-玉米-豆粕型日粮瘤胃发酵及微生物蛋白合成效率的影响。结果表明,RSI内pH值不受有机物进食量和外流速度的影响;在低外流速度下各OMI组瘤胃内0～72h干物质、有机物、粗蛋白、NDF、ADF降解率均高于高外流速度(P＜0．05)。随着OMI的增加,同一外流速度下日粮可发酵有机物产生VFA量(TVFA/FOM,mmol/g)逐渐下降(P＜0．05);相同OMI组饲料降解氮转化为微生物氮的效率在外流速度为0．02h时显著高于高外流速度(P＜0．05)。     

运用人工瘤胃筛选奶牛日粮配方

运用DFCOS-Ⅱ型双外流连续培养系统,对精粗比为4：6的A、B、C、D、E5种泌乳料的应用效果进行了评价。结果表明,各组的瘤胃液pH值均在正常范围之内;A、B组的NH3-N浓度低于C、D、E组;A、B组的总挥发性脂肪酸含量均高于C、D、E3组。     

瘤胃持续模拟技术的研究

本研究包括瘤胃持续模拟装置(RSI)的设计和RSI稳定性与模拟效果的研究两部分。RSI由发酵系统、温度控制系统、搅拌系统和样品收集系统组成,核心是6个发酵罐。以6头瘘管牛为对照,用精粗比为1:1的日粮研究了RSI的稳定性和模拟效果。结果表明,RSI的NH_3-N浓度、TVFA浓度、pH和每天产气量的变异系数都小于7％;当外流速度和固体颗粒控制孔径增加时NH_3-N浓度和TVFA浓度下降,pH值上升;而喂料量增加则有相反的结果。当RSI的外流速度为1.36ml/min、控制孔径1.5mm和喂料量30g/d时,发酵罐内的NH_2-N浓度、TVFA浓度和pH值与牛瘤胃液的测定值最接近(P>0.05),各种挥发性脂肪酸的比例也没有显著差异(P>0.05)。     

新型单外流瘤胃体外连续培养系统

在总结前人研制的人工瘤胃基础上加以改进,自行设计制作了一套新的单外流瘤胃体外连续培养系统。该装置的特点是发酵罐独特的密封设计,发酵罐可更换式内网代替以往的尼龙袋,及独特的搅拌方式设计。通过内网孔径、搅拌方式及稀释率的调整,可提高人工瘤胃发酵的仿生性能。为了验证新设备的稳定性和可行性,设计了稀释率对瘤胃体外连续培养系统发酵参数的影响试验。试验采用对照试验设计,设计2个稀释率,每小时分别为发酵罐体积的3%和6%,即缓冲液流量分别为0.5和1 mL/min,日喂料量也随之分别为12和18 g。每个稀释率为一组,每组设3个重复,活体羊为对照组。分别测定瘤胃和发酵罐内的pH、NH3-N和挥发性脂肪酸质量浓度,以评定人工瘤胃体外连续培养系统的模拟效果。系统运行的第3天～第5天为样本采样期。试验结果表明:当日粮精粗料比为30:70时,随着稀释率的提高,pH逐渐升高,NH3-N质量浓度下降。乙酸、丙酸与丁酸的摩尔比例和总挥发性脂肪酸质量浓度间差异不显著。在试验条件下,日粮精粗料比为30:70时,瘤胃体外连续培养系统的稀释率为3%时,与活体羊最接近。认为瘤胃体外连续培养系统的稀释率应与相应日粮类型及(或)营养水平的瘤胃食糜外排速度一致。     

Evaluation of a single‐flow continuous culture fermenter system for determination of ruminal fermentation and enteric methane production

A 4‐unit, single‐flow continuous culture fermenter system was developed to assess in vitro nutrient digestibility, volatile fatty acid (VFA) concentration and daily enteric methane (CH₄) production of ruminant diets. The objective was to develop a closed‐vessel system that maintained protozoal populations and provided accurate predictions of total CH₄ production. A diet of 50% orchardgrass (Dactylis glomerata L.) and 50% alfalfa (Medicago sativa L.) was fed during 4, 10‐day periods (7‐day adaptation and 3‐day collection). Fermenters were fed 82 g of dry matter (DM)/day in four equal feedings. pH and temperature were taken every 2 min, and CH₄ concentration was measured every 10 min. Samples for DM and protozoal counts were taken daily, and daily effluent samples were collected for determination of DM, VFA and NH₃‐N concentrations. There was no effect (p > 0.17) of adaptation versus collection days on vessel and effluent DM, temperature or pH. Initial protozoal counts decreased (p < 0.01), but recovered to initial counts by the collection period. Total VFA, acetate, propionate and isobutyrate concentrations did not differ (p ≥ 0.13) among periods or days of the collection period. There was no difference (p ≥ 0.37) among days or periods in total daily CH₄ production and CH₄ production per g of OM, NDF, digestible OM or digestible NDF fed. Data collected throughout 4 experimental periods demonstrated that the system was able to reach a steady state in fermentation well within the 7‐day adaptation period and even typically variable data (i.e., CH₄ production) were stable within and across periods. While further research is needed to determine the relationship between this system and in vivo data, this continuous culture fermenter system provides a valid comparison of in vitro ruminal fermentation and enteric CH₄ production of ruminant diets that can then be further validated with in vivo studies.     

Pathophysiological evaluation of subacute ruminal acidosis (SARA) by continuous ruminal pH monitoring

Evaluation of the radio‐transmission pH‐measurement system for monitoring the ruminal pH and subacute ruminal acidosis (SARA) in cattle is described. This is done in order to reveal the possible application of this system for detection and pathophysiological research of SARA by continuous ruminal pH measurement. The possibility of using this system for assessment of the ruminal pH in SARA cattle, and the presence of negative correlation between the ruminal pH and ruminal temperature in heathy and SARA cattle were determined. In addition, the 16S rRNA gene pyrosequencing analysis showed that the ruminal microbial community was simpler in SARA cattle, and the bacterial numbers in SARA cattle were lower than those in healthy hay‐fed cattle. Concentrate feeding might have reduced the diversity of the ruminal microbial community. Changes in the ruminal microbial community of SARA cattle might be related to the changes in ruminal pH followed by the decrease in the number of some bacteria. Continuous monitoring of the ruminal pH using the radio‐transmission pH‐measurement system would be applied for detection and prevention of SARA in the field and pathophysiological research of SARA, including ruminal zymology and bacteriology, which have been determined previously by sampling of the ruminal fluid and measuring of ruminal pH.     

阴离子饲粮对活体外瘤胃发酵特性和营养物质消化的影响

应用双外流连续培养系统模拟瘤胃发酵,研究不同阴阳离子差(DCAD)水平的阴离子饲粮对活体外瘤胃发酵和营养物质消化率的影响。试验分2期进行,每期12个发酵罐,3个1组,分别投入4种不同DCAD水平的饲粮:+120-、9-、77-、145 mEq/kgDM,后3种饲粮通过添加阴离子添加剂降低DCAD。结果表明:①阴离子饲粮对瘤胃发酵pH值、氨态氮浓度、总挥发性脂肪酸浓度、主要挥发酸的摩尔比例均没有显著影响(P>0.2)。②对饲粮干物质、有机质、中性洗涤纤维、粗蛋白消化率没有显著影响(P>0.2)。③对瘤胃微生物合成效率没有显著影响(P>0.2)。试验结论为阴离子饲粮对活体外瘤胃发酵和饲粮营养物质消化率没有显著影响。     

Technical note: development and testing of a radio transmission pH measurement system for continuous monitoring of ruminal pH in cows

An indwelling ruminal pH system has been used for the continuous recording of ruminal pH to evaluate subacute ruminal acidosis (SARA) in dairy cows. However this system does not allow the field application. The objective of this study was to develop a new radio transmission pH measurement system, and to assess its performance and usefulness in a continuous evaluation of ruminal pH for use on commercial dairy farms. The radio transmission pH measurement system consists of a wireless pH sensor, a data measurement receiver, a relay unit, and a personal computer installed special software. The pH sensor is housed in a bullet shaped bolus, which also encloses a pH amplifier circuit, a central processing unit (CPU) circuit, a radio frequency (RF) circuit, and a battery. The mean variations of the measurements by the glass pH electrode were +0.20 (n = 10) after 2 months of continuous recording, compared to the values confirmed by standard pH solutions for pH 4 and pH 7 at the start of the recording. The mean lifetime of the internal battery was 2.5 months (n = 10) when measurements were continuously transmitted every 10 min. Ruminal pH recorded by our new system was compared to that of the spot sampling of ruminal fluid. The mean pH for spot sampling was 6.36 ± 0.55 (n = 96), and the mean pH of continuous recording was 6.22 ± 0.54 (n = 96). There was a good correlation between continuous recording and spot sampling (r = 0.986, P < 0.01). We also examined whether our new pH system was able to detect experimentally induced ruminal acidosis in cows and to record long-term changes in ruminal pH. In the cows fed acidosis-inducing diets, the ruminal pH dropped markedly during the first 2 h following the morning feeding, and decreased moreover following the evening feeding, with many pulse-like pH changes. The pH of the cows showed the lowest values of 5.3-5.2 in the midnight time period and it recovered to the normal value by the next morning feeding. In one healthy periparturient cow, the circadian changes in ruminal pH were observed as a constant pattern in the pre-parturient period, however that pattern became variable in the post-partum period. The frequency of the ruminal pH lower than 5.5 increased markedly 3 and 4 days after parturition. We demonstrated the possible application of a radio transmission pH measurement system for the assessment and monitoring of the ruminal pH of cows. Our new system might contribute to accurate assessment and prevention of SARA.     

Influence of an aerobic fungus grown on solid culture on ruminal degradability and on a mixture culture of anaerobic cellulolytic bacteria

In this work, the effect of a solid fungal culture of Aspergillus niger (An) grown on coffee pulp on the in situ ruminal degradability (RD) of corn stover was evaluated. In addition, the effect of its extracts on the in vitro dry matter disappearance (IVDMD) and on a mixed culture of anaerobic cellulolytic bacteria (MCACB) was also investigated. The solid ferment was a crude culture of An, grown on coffee pulp. Regarding in situ RD, a significant difference (p < 0.05) was found between treatment with 200 g/day of the solid culture and control (no solid culture added) on dry matter, crude protein and neutral detergent fibre on RD. All the water extracts (pH 4, 7 and 10) enhanced IVDMD and stimulated the cellulolytic activity on a MCACB. Ultrafiltration results showed that active compounds with a molecular weight lower than 30 kDa were responsible for the effect on MCACB. Such results suggest that the effects of the solid An culture in RD are related to the presence of water soluble compounds having a molecular weight lower than 30 kDa.     

Signals for identifying cows at risk of subacute ruminal acidosis in dairy veterinary practice

Controlling rumen disorders is critical to ensure successful dairy herd health management. Lactation diets of dairy cows are commonly rich in concentrates and low in physically effective fibre. Feeding of these diets increases the risk of rumen disorders with far‐reaching consequences for cattle health, welfare and sustainability of dairy production. The term subacute ruminal acidosis or SARA is often used as a synonym for poor rumen health. Being subclinical, SARA lacks of clear symptoms and is therefore difficult to diagnose and to control in the practice. This review article summarises common and identifies new direct and indirect cow signals related to SARA. We have performed a scientific evaluation and interpretation of each of these cow signals by highlighting their advantages and disadvantages from the practitioner's point of view. The gold standard of SARA cow signals still remains direct measurement of ruminal pH. However, continuous pH monitoring is cost‐intensive and often biased by sensor drift. Single‐point ruminal pH measurements by oral stomach tubing or rumenocentesis have strong limitations. Therefore, there is a need for reliable and robust markers of SARA that are easily accessible and inexpensive. Such indirect parameters are the observation of chewing and feeding activities, as well as the monitoring of milk, faecal, urine and blood variables. Also, novel technologies that allow rapid and non‐invasive measurement of the rumen mucosa thickness and ruminal motility patterns might provide advantages in SARA diagnosis. Due to several constraints of these indirect diagnostic tools, such as limited specificity and sensitivity, we strongly recommend using a combination of the signals to reliably identify cows at risk of SARA in a dairy herd.     

CNCPS研究综述——瘤胃发酵

康奈尔净碳水化合物-蛋白质体系(CNCPS)是在综合了有关研究瘤胃发酵的最新研究成果和理论的基础上,结合计算机技术形成的一套新的技术体系,在生产中体现了很好的实用性和优越性。通过阐述CNCPS对瘤胃微生态、瘤胃微生物、瘤胃微生物的组成、瘤胃发酵和过瘤胃、氮损失和内源氮循环的研究,从该体系的最初研究出发,揭示该体系的基本框架,为深入理解和应用CNCPS提供参考。     

连续培养瘤胃模拟发酵的工作参数设置研究进展

体外培养法作为反刍动物营养学研究的重要方法,主要有批次培养法和连续培养法两种。由于连续培养法能够更好地模拟瘤胃内发酵情况,其应用也更为广泛。但连续培养瘤胃模拟装置的主要运行参数多,如温度、pH、稀释率、缓冲液与瘤胃液接种比、搅拌速率与方式等,且不同运行参数设置以及参数的组合对试验结果影响较大,因此作者在总结前人研究结果的基础上,就不同工作参数对连续培养瘤胃模拟发酵过程中挥发性脂肪酸、干物质消失率、pH、酶活、原虫数量、微生物蛋白等指标的影响进行了综述。     

持续动态瘤胃发酵系统的结构功能比较研究进展

持续动态瘤胃发酵系统是在体外模拟瘤胃内发酵环境,用于瘤胃微生物代谢以及评定日粮营养价值等方面研究的机械装置。该装置是由一系列具有不同功能的设备组成。目前较新的人工瘤胃模拟系统主要能实现发酵环境中各发酵参数的实时监控并对发酵产物如产气量等进行准确计量,但与实体瘤胃内环境还存在一定差距。本文通过对国内外几种典型的持续动态瘤胃发酵系统的各部分结构和功能进行对比分析,比较各自的优缺点,提出了较为合理的设计方法。总之,持续动态瘤胃发酵系统的设计向着自动化方向发展,但在食糜样品的采集方法等方面还需改进。