Differences In Gas Production Research Articles

Research on Factors Influencing the Production of Deep Shale Gas Wells in Weiyuan Block : A Case Study of X Well on Platform A

Abstract The practice of Weiyuan deep shale gas development shows that there are many factors that affect the gas production, resulting in significant differences in gas production between wells in the same region and on the same platform. In response to the phenomenon of low gas production, low wellhead pressure, and high flowback rate in Well X on Platform A, using data from drilling, fracturing, and gas production profile testing, this study examines the impact of geological and engineering factors on gas well production through gray correlation analysis and geological engineering integrated numerical simulation methods. The results show that: ① The production of adjacent wells reduces the formation energy, resulting in a large pressure drop rate after the pump is stopped in the corresponding fracturing section of the well, poor fracturing effect and low gas production contribution; ② The order of the influence of geological factors on the gas production rate of each section is: gas content > Si content > Al content > GR value> Ca content;③The segment with natural fractures and faults contributes significantly to gas production, but its long-term effectiveness needs further evaluation. This study will provide useful references for target location optimization, fracturing design optimization, and overall development deployment of deep shale gas horizontal wells in Weiyuan.

Experimental study on the mechanism of coal spontaneous combustion inhibition by degradation of white-rot fungus

To investigate the mechanism of inhibition of spontaneous combustion of coal by degradation of white-rot fungus, the changes of macroscopic oxidizing characteristics and microstructure of the degraded coal were investigated by the programmed temperature-raising test and the in situ Fourier-transform infrared spectroscopy experiments. The difference in gas production between the degraded coal and the blank samples indicated that the degradation inhibited the oxidation process of coal, and the intensity of the inhibition effect was different at different oxidation stages. The strongest inhibition effect was found in the accelerated oxidation stage, i.e. 80–140 °C. To further analyze the micro-mechanism of the degradation of Phanerochaete chrysosporium affecting the spontaneous combustion of coal, the relative contents of active functional groups in coal samples were compared. The results showed that the degradation affected the relative contents of hydroxyl, aliphatic hydrocarbon, and oxygenated functional groups in coal. Among them, the most significant changes of –OH and –CO- were observed at 80–140 °C. Thus, it was analyzed that Phanerochaete chrysosporium could degrade the macromolecular structure of coal by generating biological enzymes to reduce the number of oxidizable functional groups such as –OH, –CH2, –CH3, –CO-, and so on, thus reducing the risk of spontaneous combustion of coal.

Characterization of Lactic Acid Bacteria and Yeast from Grains as Starter Cultures for Gluten-Free Sourdough.

With the increasing number of people affected by gluten consumption-related diseases, adhering to a gluten-free (GF) diet is the most effective preventive measure. Herein, we aimed to isolate and characterize the functional properties of autochthonous lactic acid bacteria (LAB) and yeast from various GF sourdoughs to determine their suitability in starter cultures for sourdough preparation. Three LAB, Weissella confusa BAQ2, Lactobacillus brevis AQ2, Leuconostoc citreum YC2, and Saccharomyces cerevisiae BW1, were identified. The isolated LAB exhibited greater TTA, faster acidification rates, and higher acid tolerance than commercial LAB. W. confusa BAQ2 exhibited the highest EPS production, W. confusa BAQ2 and L. brevis AQ2 showed high maltose utilization, and S. cerevisiae BW1 exhibited the highest CO2 production rate. Accordingly, all four microbial strains were mixed for the starter culture. The sourdough prepared with starter cultures exhibited differences in gas production depending on fermentation time, which influenced the volume of GF bread dough. GF bread prepared with fermented sourdough exhibited a 16% higher specific volume and enhanced crumb firmness and elasticity than that prepared using non-fermented sourdough. Thus, autochthonous LAB strains isolated from various GF sourdoughs can be used together to improve the quality of sourdough bread, demonstrating their potential for use in starter cultures for GF sourdough production.

Estimating greenhouse emissions from sanitary landfills using Land-GEM and IPCC model based on realistic scenarios of different urban areas: a case study of Iran.

This study examined the emission of greenhouse gases from municipal solid waste disposal centers in different regions of Iran based on different scenarios. Assuming landfill site opening in 2012 and considering the 20-year plan period for its usage, the amount of wastes entering the landfill site was calculated for 2012-2032. For calculating the production of methane (CH4) and other gases during different years of the project, Land-GEM and IPCC model were used. We defined 9 scenarios for these two models based on the growth rate of population and waste generation. The results revealed that the lowest amount of gas emission in nine scenarios by Land- GEM model was related to non-methane organic compounds (NMOCs). According to the results obtained, the total emissions of greenhouse gases from sanitary landfills for Iran in 2032 were 3,844,000 Mg/year, the largest and lowest amounts of gas emission were related to Tehran region, 860,400 Mg/year, and the South Coast area of the country,138,200 Mg/year, respectively. The major section of the gas production in both landfills was related to greenhouse gas and carbon dioxide emissions. The difference in gas production in the studied regions was due to differences in the percentage of moisture and organic compounds.

Evaluation of the spontaneous combustion of soaked coal based on a temperature-programmed test system and in-situ FTIR

To explore the influence of long-term water immersion on the spontaneous combustion characteristics of coal, temperature-programmed test system and In-situ Fourier transform infrared spectroscopy (In-situ FTIR) were used. Differences in gas production of soaked coal and raw coal showed that the process of long-term water immersion played a different role before and after critical temperature. In the stage of surface oxidation, moisture could inhibit the spontaneous combustion of coal, when the critical temperature point was exceeded, it played a promoting role instead. As an explanation in support of the above arguments, the relative contents of active functional groups in raw and soaked coal were compared, which indicated that the process of water immersion could affect relative contents of hydroxyl, aromatic hydrocarbon, aliphatic hydrocarbon and oxygen-containing functional groups, giving rise to an acceleration in the reaction process of coal oxygen and exhibiting higher tendencies toward spontaneous combustion. A practical consequence of this finding is the soaking mechanism should not be neglected in any precautionary or preventive measures to avoid potential spontaneous combustion in overlying goaf of shallowly buried and close distance coal seams.

PSXII-11 In vitro fermentative parameters of diets containing increasing inclusions of soybean molasses for sheep

Abstract The objective of this study was to evaluate the effects of increasing inclusion of soybean molasses (SM) in sheep diets on in vitro gas production, pH, N-NH3 and VFA. Three ruminally-cannulated adult sheep were used as donors of inoculum. The treatments consisted of diets containing 0, 10, 20 and 30% of SM (DM basis) with forage: concentrate ratio of 20:80. The experimental design was completely randomized with repeated measurements over time (2, 6, 12 and 24 hours). Flasks with a volume of 50 mL were used for incubation. Approximately, 0.2 g of sample, 10 mL of the inoculum and 20 mL of the McDougall buffer solution were added into the flasks. Each time consisted of 6 bottles per treatment and 2 bottles without sample (n = 104). Gas production was measured by a pressure transducer. Concentrations of N-NH3 was determined using micro-Kjeldhal apparatus, and VFA was determined by gas chromatography. The disappearance of DM was evaluated by filtration using nylon bags (50 μm porosity). The data were analyzed using the MIXED procedure of SAS. Orthogonal contrasts were used to determine the linear and quadratic effect of SM inclusion. Total concentration of VFA, pH and gas production per g disappeared (mL/g DM disappeared) had no significant effect (P > 0.05). Gas production per incubated g (mL/g DM incubated), disappearance of DM (%) showed increasing linear effect (P < 0.05), with values of 92.87 to 119.64 and 58.48 to 75.40 for 0 and 30% of SM, respectively. N-NH3 (mg/dL) presented a linear decreasing effect (P < 0.05), ranging from 19.27 to 16.95, for 0 and 30% of SM, respectively. The inclusion up to 30% of SM (DM basis) in sheep diets did not affect in vitro fermentation parameters and did not promote a difference in gas production per g disappeared when compared to other treatments.

Simulations of In-Situ Upgrading Process: Interpretation of Laboratory Experiments and Study of Field-Scale Test

Summary In–situ upgrading (IU) is a promising method of improved viscous– and heavy–oil recovery. The IU process implies a reservoir heating up and exposure to a temperature higher than 300°C for a time period long enough to promote a series of chemical reactions. The pyrolysis reactions produce lighter oleic and gaseous components, while a solid residue remains underground. In this work, we developed a numerical model of IU using laboratory experience (kinetics measurements and core experiments) and validated the results by applying our model to an IU field–scale test published in the literature. Finally, we studied different operational conditions in a search for energy–efficient configurations. In this work, two types of IU experimental data are used from two vertical–tube experiments with Canadian bitumen cores (0.15 and 0.69 m). A general IU numerical model for the different experimental setups has been developed and compared with experimental data, using a commercial reservoir–simulator framework. This model is capable of representing the phase distribution of pseudocomponents, the thermal decomposition reactions of bitumen fractions, and the generation of gases and residue (solid) under thermal cracking conditions. Simulation results for the cores exposed to a temperature of 380°C and production pressure of 15 bar have shown that oil production (per pseudocomponent) and oil–sample quality were well–predicted by the model. Some differences in gas production and total solid residue were observed with respect to laboratory measurements. Computer–assisted history matching was performed using an uncertainty–analysis tool with the most–important model parameters. To better understand IU field–scale test results, the Shell Viking pilot (Peace River) was modeled and analyzed with the proposed IU model. The appropriate gridblock size was determined and the calculation time was reduced using the adaptive mesh–refinement (AMR) technique. The quality of products, the recovery efficiency, and the energy expenses obtained with our model were in good agreement with the field test results. In addition, the conversion results (upgraded oil, gas, and solid residue) from the experiments were compared with those obtained in the field test. Additional analysis was performed to identify energy–efficient configurations and to understand the role of some key variables (e.g., heating period and rate and the production pressure) in the global IU upgrading performance. We discuss these results, which illustrate and quantify the interplay between energy efficiency and productivity indicators.

Investigating the impact of seasonal temperature variation on biogas production from covered anaerobic lagoons treating slaughterhouse wastewater using lab scale studies

Low-rate anaerobic digestion technology can be influenced by environmental conditions, most notably temperature. The effect of temperature on lipid degradation and crust formation in lagoon digesters treating red meat processing (RMP) wastewater is especially pronounced, impacting on the anaerobic digestion process, resulting degradation and biogas generation. This study investigates the effect of temperature reduction from 38 °C to 25 °C to simulate the annual seasonal temperature range experienced in a covered anaerobic lagoon treating slaughterhouse wastewater located in South-East Queensland, Australia. A step-wise temperature reduction was carried out over a three-month period in continuous stirred tank reactors, and anaerobic digestion performance was compared to digesters operating at optimal mesophilic conditions. After reaching the minimum seasonal temperature, the organic loading rate was increased to identify the limits for organic loading at the different temperature levels. Lower temperatures had a negative impact on degradation efficiency, biogas production, and process stability. The translation of lab scale results to commercial scale operation indicated a 30% reduction in biogas production at a temperature of 31 °C, which corresponded to the highest annual temperatures in the covered anaerobic lagoon. A further decrease to 25.5 °C, which represents the lowest annual temperature in the lagoon, with an increase of the organic loading rate caused up to 80% difference in gas production and negatively influenced process stability. Economic assessment indicated that by operating lagoons under optimal mesophilic conditions, natural gas consumption could be offset with biogas to reduce yearly expenditure of natural gas by up to 25.4%.

Numerical simulation of multi-seam coalbed methane production using a gray lattice Boltzmann method

Multi-zone or multi-seam commingled production in CBM reservoir is an attractive option for extending and/or increasing existing gas production. To solve the problem of interlayer interference during commingled production, with varying permeability and pressure difference between coal seams, numerical simulations are carried out using a gray lattice Boltzmann method. Under different conditions of multi-seam commingled production, the pressure and velocity distributions are obtained. Then, the effects of permeability and pressure contrast on multi-seam commingled production are investigated. The results show that under the condition of commingled production with different permeability contrast, a greater permeability contrast will lead to a greater difference in gas production of each seam. And the smaller the reservoir permeability is, the faster the decrease of reservoir pressure near the wellbore is. For commingled production with different pressure contrast, the interlayer interference coefficient increases linearly with the increase of the pressure contrast. The interference degree of low pressure seam is far greater than that of high pressure seam. A lower reservoir permeability will lead to a greater interference coefficient. The research results provide a basis for revealing the interlayer interference mechanism, production dynamic analysis and production system optimization in multi-seam commingled production.

Differences in nutritional characteristics of three varieties of sorghum grain determine their in vitro rumen fermentation

The effect of phenolic compounds and protein matrix on microbial fermentation of three sorghum grains (S1, S2 and S3) were studied in vitro. Total phenolics and total tannins concentration (g/kg dry matter, DM) were 1.5 and 0.2 for S1, 19.3 and 8.1 for S2 and 2.6 and 1.3 for S3. Protein enzymatic digestibility was 0.614, 0.226 and 0.454, respectively. Trial 1 was conducted for 24 h, without or with polyethylene glycol (PEG) to determine the effect of phenolic compounds on fermentation. Without PEG, gas production for S1 was the highest after 24 h (257, 237 and 238 mL/g organic matter, for S1, S2 and S3; p<0.05), and higher proportion of propionate at the expense of acetate was recorded with S3 after 6 h. Gas produced with S1 and S3 remained unaffected (p>0.10), but increased in S2 by 0.21 to 0.30 with vs. without PEG. No differences in gas production between S1 and S2 were observed with PEG, S3 recording the lowest (p<0.05) values from 8 h onwards. Addition of PEG reduced proportion of butyrate (p<0.05) and increased three-fold lactate (1.62 vs. 4.98 mM; p<0.001). In Trial 2 (12 h) gas production followed a similar pattern. Without PEG, starch disappearance was the highest in S1 (0.356, 0.231 and 0.216, respectively), but no differences were recorded with PEG. Considering differences in protein digestibility and the effect of phenolic compounds, the effect of starch nature and structure on fermentation is apparently minor. Colour of grain is not necessarily related to phenolic compounds proportion or rumen utilization.

Effect of Moringa oleifera leaf on the efficiency to increase protein supply to ruminants

Moringa oleifera leaf was investigated for nutritional quality, presence of tannins and its activity using polyethyelene glycol (PEG) and in vitro study of protein degradation in the rumen. The antibiotic growth promoter (AGP), Monensin was used as an external control to compare with the degradation of Moringa leaves. The different forms of tannin content in Moringa leaves were very negligible. Total phenol, total tannin, condensed tannin and hydrolysable tannin contents of Moringa leaves were 3.92±0.42, 1.19±0.14, 0.57±0.06 and 0.07±0.02 mg/g, respectively. The in vitro gas production, organic matter digestibility (OMD%) and metabolizable energy (ME) content of Moringa leaves were 54.39 ml, 77.44% and 11.14 MJ/kgDM, respectively. There were no significant differences in gas production, in vitro OMD% and ME content in the presence of tannin binding agent PEG. These results indicated that the different forms of tannin present in Moringa leaves are not active tannins, therefore, feeding Moringa leaves are safe for the ruminant animals. The kinetic study of in vitro gas production with Moringa leaves and Monensin showed almost similar results and there was no significant difference among them but higher values were found in the control indicated that Moringa leaves have the ability to inhibit the breakdown of protein in the rumen as of Monensin. On the contrary, soluble protein concentration was increased 182% with the addition of Moringa leaves compared to control and the values were almost close (213%) with Monensin during the 12h incubation period. The pellet protein concentration was also increased (119%) with Moringa leaves and Monensin (115%) compared to control although there was no significant difference between them. Therefore, it can be concluded from the present findings that feeding Moringa leaves appeared to be an alternative source of protein and are safe for ruminant animals. Moringa leaves have been shown to alter favorably ruminal protein fermentation characteristics thus spare protein by a decreased breakdown/deamination of protein/amino acids that functions as of Monensin.DOI: http://dx.doi.org/10.3329/bjas.v44i1.23142 Bang. J. Anim. Sci. 2014. 44 (1): 46-51

Effects of a selection of additives on in vitro ruminal methanogenesis and in situ and in vivo NDF digestibility.

The effects of 18 essential oils, yeast, Quebracho tannin and Quillaja saponin on ruminal methane and gas production (GP) were studied in vitro. A lactating cow diet was incubated with rumen inoculum. Doses of the additives (mg/L) were: essential oils = 500; tannin = 67; yeast = 8.35 and 16.7; and saponin = 300. Lemongrass, estragole, eugenol, geraniol, limonen, thyme oil and thymol produced less gas (overall mean 33.8 mL/200 mg dry matter (DM)) than control (43.6 mL/200 mg DM; P < 0.001). Methane produced (mL/200 mg DM) by guaiacol (10.7), lemongrass (9.6), limonene (11.4), thyme oil (10.9) and thymol (2.1) was lower than control (12.5) (P < 0.001). Methane percentage on total GP was lower (P < 0.001) for cinnamic alcohol (25.4), guaiacol (24.5), thymol (19.7) and vanillin (26.3) than control (28.8). In a second experiment, thymol, guaiacol and yeast were added to the diet of dry fistulated cows to determine in situ neutral detergent fiber digestibility (NDFD) of six forages and in vivo dietary NDFD. Thymol and yeast decreased in situ NDFD after 24 h (33.9% and 33.5% vs. 38.1%; P = 0.008). Thymol decreased in vivo total tract NDFD (40.8% vs. 51.4%; P = 0.02). Differences in GP and methane levels were registered within classes of additives. A careful selection of additives may allow for the manipulation of ruminal fermentation.

밤 가공 부산물의 반추가축용 사료 가치 평가: in vitro 반추위 배양

밤의 가공과정에서 임업 부산물로 생산되는 율피(밤껍질)는 밤 생산량의 50%를 차지하며, 사료비 저감을 위한 반추동물의 사료원으로서 이용 가능성이 있으나 이에 대한 연구는 미비한 실정이다. 본 연구에서는 밤의 가공 부산물인 1, 2차 율피의 반추동물용 사료로서의 영양적 가치와 반추위 발효 특성을 분석하기 하기 위해 1, 2차 율피의 영양소를 분석하고, 48시간 동안 in vitro 반추위 발효 실험을 실시하여 율피의 첨가 수준에 따른 in vitro 반추위 건물 소화율 및 가스 발생량을 측정하였다. In vitro 실험의 기본 사료로는 시중에서 판매되는 유산양 TMR을 이용했으며, 기본 사료와 1차 율피 및 2차 율피의 비율을 달리하여 13개의 처리구로 실험을 실시하였다. 처리구는 2차 율피 100%, 1차 율피 100%, 2차 율피와 1차 율피의 1:1 혼합구, TMR 100% 및 TMR을 2차 율피, 1차 율피 또는 1, 2차 율피 혼합으로 각각 5%, 10%, 15% 대체한 처리구이다. 율피의 일반 성분분석에서 1차 율피는 2차 율피에 비해 섬유소(NDF, ADF, 리그닌) 함량이 전체적으로 높고 이에 따라 비섬유소탄수 화물의 함량은 낮으나, 그 외의 영양소에서는 차이를 보이지 않았다. In vitro 반추위 건물 소화율은 유의적으로(p<0.05) 2차 율피(71.97%)가 가장 높았고, 1차 율피(42.80%)가 가장 낮았다. 2차 율피의 첨가 수준이 증가됨에 따라 건물소화율은 변화가 없었으며, 1차 율피의 첨가에 따라서는 소화율이 감소하는 경향을 보였다. 가스 발생량은 2차 율피 처리구에서 48시간 가스 발생량 및 발생 속도가 가장 높았고, 1차 율피 처리구에서 가장 낮았으며, TMR을 율피로 15%까지 대체하였을 때 가스 발생량의 차이는 유의하지 않았다. pH 또한 유의적으로(p<0.05) 2차 율피(6.33)에서 가장 낮았고, 1차 율피(6.50)에서 가장 높았다. 결론적으로 2차 율피는 반추동물의 사료 자원으로서 이용가치가 충분히 있으며, 1차 율피의 경우 상대적으로 사료가치가 떨어지나 조사료를 일부 대체하는 것은 가능할 것으로 판단된다. 하지만, 율피의 사료 가치를 보다 올바로 평가하기 위해서는 동물을 이용한 in vivo 대사, 소화, 성장 및 기호성 실험이 필요한 것으로 사료된다. During the manufacturing process of chestnut, 50% of biomass is produced as chestnut shell (CS) or chestnut hull (CH), a forestry by-product. Due to its high fiber content and economic benefit, there is a possibility of using chestnut hull as a supplement for a ruminant diet. Few studies, however, have been conducted on evaluating nutritive value of chestnut hull for ruminant animals. The objective of this study were thus to analyze chemical composition of CS, a by-product after the first processing of chestnut, and CH, a by-product after the second processing, and access in vitro rumen fermentation characteristics of them. For the in vitro fermentation using strained rumen fluid obtained from a fistulated Hanwoo steer, commercial total mixed ration (TMR) for dairy goat was used as a basal diet and was replaced with different proportions of chestnut shell and hull. A total number of 13 treatments were carried out in this study: 100% TMR, 100% CS, 100% CH, a mix with 50% CS and 50% of CH (MIX), TMR replaced with 5%, 10%, or 15% of CS, CH, or MIX, respectively. For each treatment, in vitro dry matter digestibility (IVDMD) and pH after 48 hours of rumen fermentation were measured. Gas production at 6, 12, 24, 48 hours of incubation was also analyzed. Compared to CH, CS contains higher level of fiber (NDF, ADF, lignin) and consequently has a lower amount of non-fiber carbohydrate, but no difference was observed in the other nutrients (i.e. crude protein, crude fat, and ash). IVDMD was significantly (p<0.05) the highest in 100% CH (71.97%) and the lowest in 100% CS (42.80%). Addition of CH by replacing TMR did not affect IVDMD, while an increase in the proportion of CS tended to decrease IVDMD. The total gas production after 48 hours of incubation and the rate of gas production were also the highest in 100% CH and the lowest in 100% CS (P<0.05). Likewise, the pH after 48 hours of fermentation was significantly (p<0.05) the lowest in 100% CH (6.33) and the highest in 100% CS (6.50), and no significant difference in gas production was observed when TMR was replaced with CS or CH up to 15% (P>0.05). In conclusion, CH may successfully be used for a supplement in a ruminant diet. The nutritive value of CS is relative low, but can replace, if not 100%, low quality forage. This study provides valuable information about the nutritive value of CS and CH. An in vivo trials, however, is needed for conclusively accessing the nutritive value of CS and CH.

Effects of phenolic compounds in three oak species on in vitro gas production using inoculums of two breeds of indigenous Iranian goats

The capabilities of rumen fluid (RF) from two indigenous Iranian goats (i.e., Markhoz, Alamout) to ferment tanniniferous (i.e., oak leaves) and non-tanniniferous (i.e., a mixture of lucerne hay and barley grain) feeds were studied. Five air dried samples from each of three oak species (i.e., Quercus persica, Quercus infectoria, and Quercus libani) were used to determine their chemical composition, phenolic compounds and protein precipitable phenolics (PPP). In three runs of in vitro gas production, the influence of non-tannin containing substrate incubated with either RF (i.e., Markhoz or Alamout) was assessed. Gas production (GP) was recorded from 1 to 96h of incubation. Effects of tannins on in vitro gas production, in vitro organic matter disappearance (IVOMD) and estimated metabolisable energy (ME) were assessed by a polyethylene glycol (PEG) tannin bioassay. There were no differences in gas production and IVOMD for a non-tannin substrate incubated with RF from either breed of goat. However, RF from Markhoz goats produced consistently more gas than RF from Alamout goats among oak species. The PEG treatment improved (P<0.01) the IVOMD in RF and estimated ME from both breeds of goats for all oak species. The RF from Markhoz goats fermented oak leaves more effectively than RF from Alamout goats, possibly due to the presence of tannin-degrading bacteria.

Effects of preservation procedures of rumen inoculum on in vitro microbial diversity and fermentation

Sheep rumen contents were used as inoculum for an in vitro semi-continuous incubation system to study whether preservation method affects microbial fermentation pattern. Rumen fluid was filtered and either used immediately as inoculum (CTL) or dispensed into 110 mm × 16 mm tubes, that were stored refrigerated at 6 °C for 4 h (REF) or frozen at −20 °C (FRZ), frozen in liquid N (FLN) or added with 0.04 glycerol and frozen in liquid N (FGL) for 48 h. Frozen inocula were thawed at 39 °C for 2 min before use (16 ml per bottle). Two 24 h incubations with four bottles per treatment were completed. The microbial utilisation of added glycerol after thawing in FGL increased total gas production ( P<0.05) and 24 h volatile fatty acid (VFA) production ( P<0.05), and also increased propionate and butyrate proportions at the expense of acetate. The other freezing inocula ( i.e., FLN and FRZ) reduced the rate of gas production (as ml/g dry matter per hour), compared with CTL in the first 2 and 4 h of incubation ( P<0.05), but this was compensated by increased fermentation at 8 and 12 h, respectively. Differences in gas production did not manifest a different VFA pattern at either 6 or 24 h incubation. Bacterial diversity was slightly affected by the preservation process, and the similarity index between untreated inocula and the 24 h incubated CTL samples was 0.690–0.724. Similarity between bacterial communities in FRZ and FLN with that in CTL after incubation was 0.678. The freezing preservation method of rumen inocula for subsequent in vitro gas production studies does not affect microbial fermentation pattern or bacterial biodiversity, provided that processing is rapid enough by using a high surface to volume ratio. Freezing in liquid N is more appropriate than at −20 °C.

Stem characteristics of two forage maize ( Zea mays L.) cultivars varying in whole plant digestibility. III. Intra-stem variability in anatomy, chemical composition and in vitro rumen fermentation

The internodes of forage maize ( Zea mays L.) stems were studied at anthesis for variation in anatomy and chemical composition in relation to digestibility. The study was carried out with a short (Vitaro) and a tall (Volens) cultivar differing in whole-plant digestibility, both of which were grown in the field in the growing seasons of 1999 and 2000. Internode diameter increased from the top to the base of the stem and Vitaro had shorter and thicker internodes than Volens. The cell walls of the sclerenchyma tissue in the rind were thicker and the numbers of sclerenchyma layers around vascular bundles in the rind higher in lower than in upper internodes. The neutral detergent fibre content (NDF%) of the internodes increased from the top to the base of the stems of both cultivars, but was very high for the peduncle. NDF% was lower for Vitaro than for Volens in all internodes. The sugar content of the dry matter was highest for Internode 12, i.e., the internode near the position of the ear, and was very low for the peduncle. Vitaro always had a higher sugar content than Volens. When subjected to fermentation tests with rumen fluid in an automated gas production system, gas production values after 3, 20 or 72 h of incubation were higher for internodes from the top than for internodes from the base of the stem, and were lower for the peduncle than for Internode 14. The values were consistently higher for Vitaro than for Volens internodes; in general, this difference was most apparent for Internode 10. The differences in gas production amongst internodes and between cultivars were in line with differences expressed by in vitro digestibility measurements. Fermentation results of cross sections suggest that the cell walls in lower internodes disappeared faster and to a greater extent than the cell walls in upper internodes, except for Volens in 1999, and with the exception of the peduncle. The rate of cell wall disappearance was higher for Volens than for Vitaro, but ultimately similar amounts of cell wall material disappeared.

Host and Bacterial Virulence Factors Predisposing to Emphysematous Pyelonephritis

Emphysematous pyelonephritis (EPN) is a rare, severe, gas-forming infection of the kidney, and its precise pathogenesis remains obscure. To investigate the roles of host and bacterial virulence factors in the pathogenesis of EPN, we compared: (1) host factors in patients with EPN (n = 47) with those in patients with acute renal infections without gas formation (non-EPN; n = 79), (2) the prevalence of virulence gene in causative Escherichia coli strains from 16 of the 47 EPN cases with all 79 non-EPN cases by means of polymerase chain reaction analysis, and (3) gas volumes produced by EPN and non-EPN strains cultured in broths at 3 glucose concentrations (100, 180, and 250 mg/dL [5.6, 10.0, and 13.9 mmol/L]). Diabetes mellitus (DM) with poor glycemic control (ie, hemoglobin A1c level > 11%) and urinary tract obstruction were more prevalent in the EPN group. However, DM with poor glycemic control was the only host factor independently associated with EPN (odds ratio, 4.9; P = 0.018). EPN strains had a greater prevalence of the uropathogenic-specific protein (usp) genes. Multivariate analyses also showed the association between usp and EPN with borderline significance (odds ratio, 8.4; P = 0.057). There was no significant difference in gas production by E coli isolated from patients with or without EPN. DM with poor glycemic control and urinary tract obstruction are host factors predisposing to EPN. There was no difference in gas production between EPN and non-EPN E coli strains. The distribution of E coli virulence genes was remarkably similar between the 2 groups. However, the PapG II adhesin (papG II) gene is significantly decreased and the usp gene is increased with borderline significance in EPN E coli strains.

Effect of Different Level of Monensin Supplemented with Cold Process Urea Molasses Mineral Block on In vitro Rumen Fermentation at Different Days of Adaptation with Monensin

Effect of period of adaptation and levels of monensin were studied for microbial fermentation/ digestibility to find out the optimum period of adaptation of monensin in rumen and suitable level of monensin in wheat straw+concentrate and wheat straw+ UMMB diet. The mean digestibility of dry matter was decreased upto T-3 treatment (49.17%), however, digestibility of DM was affected upto period (P-2). NDF digestibility was affected due to treatment under P1 and P2 (p<0.05). Average digestibility of ADF was increased to 53.33% at T-3 level of monensin and P4 days of adaptation. TVFA (mmole/100 ml) were decreased from 9.49 in T-1 to 7.70 in T-7. Periods were not effectives except P2 (14 days of adaptation). Similarly, total gas was decrease with the increase of monensin levels in diet. Although acetate percentage in TVFA was not affected either due to level of monensin or period of adaptation but propionate was increased due to increase in monensin at 21 days of adaptation (P-3). Butyrate (%) was decreased significantly in T-2 to T-6 as compared to T-1 group. Total gas was significantly (p<0.01) higher in group T-1 (control) and it reduced significantly in T-5, however, differences in gas production between group T-3, T-5 and T-7 at P-1 was not significant. Methane production was reduced on P-3 and P-4 level of adaptation due to treatment. The overall result indicated that 21 days of adaptation with monensin was sufficient to mask the inhibiting effect of monensin to cell wall digestibility and 35 ppm monensin is optimum to reduce methane production and increase propionate productions. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 3 : 320-325)

Estimation of fermentable energy by the automatic in vitro gas production technique for a selection of feedstuffs incubated alone and in combination

The gas production (GP) technique has previously been used to estimate the gas volume (fermentable energy (FE)) of compound feed ingredients for ruminants (Newbold et al., 1996). It was shown that the FE content of feed mixtures was represented by the combination of the total gas from the incubation of the individual feeds. However this additivity might not be consistent throughout the incubation period. The objectives were to test whether 1. other GP parameters give better estimates of FE for simple mixtures and are they additive; 2. whether organic matter apparently degraded in the rumen (OMADR) explain differences in GP; and 3. to find out if there are any other better measures than OMADR for estimating FE.

Estimation of fermentable energy by the automatic in vitro gas production technique for a selection of feedstuffs incubated alone and in combination

The gas production (GP) technique has previously been used to estimate the gas volume (fermentable energy (FE)) of compound feed ingredients for ruminants (Newbold et al., 1996). It was shown that the FE content of feed mixtures was represented by the combination of the total gas from the incubation of the individual feeds. However this additivity might not be consistent throughout the incubation period. The objectives were to test whether 1. other GP parameters give better estimates of FE for simple mixtures and are they additive; 2. whether organic matter apparently degraded in the rumen (OMADR) explain differences in GP; and 3. to find out if there are any other better measures than OMADR for estimating FE.