Gas Production Values Research Articles

Fermentation kinetics of sainfoin hay with and without PEG

The in vitro gas production technique was applied to evaluate the biological activity of tannins in sainfoin (Onobrychis viciifolia Scop.) hay cut at four progressive phenological stages. The buffalo (Bubalus bubalis) rumen fluid was used as inoculum, polyethylene glycol (PEG) was added as specific binding agent and an alfalfa hay (AH) was used as control. All samples were analysed for chemical composition and condensed tannin (CTs). According to the phenological stage of sainfoin, crude protein gradually decreased [from 219 to 122 g/kg dry matter (DM)] and neutral detergent fibre (NDF) increased (from 391 to 514 g/kg DM). Condensed tannins showed the highest value at the first phenological stage [31.5 mg catechin equivalents (CE)/g DM], and their level significantly decreased at the subsequent growth stages. Gas production and fermentation rate were significantly affected by substrate type and PEG addition. The first stage of sainfoin showed the lowest value of gas and volatile fatty acids production and the slowest fermentation kinetics compared with the other samples, when incubated without PEG, because of the CTs effect. The incubation with PEG improved the fermentation process of the first stage of sainfoin, but no effect was registered on AH, where CTs were not detected. Among the sainfoin samples, the slowest kinetics with PEG was observed in the hay harvested at the fourth stage, probably due to its chemical composition. The use of PEG allowed to verify the effect of tannins on the in vitro fermentation characteristics of sainfoin hay.

The effect of molasses‐based pre‐fermented juice on the fermentation quality of first‐cut lucerne silage

AbstractThe aim of this study was to evaluate the possible effect of pre‐fermented juice (PFJ) on the fermentation quality and nutritive value of first‐cut lucerne (Medicago sativa L.) silage. The PFJs were prepared using barley (B), wheat (W) and grass herbages (G). Both fresh (PFJ‐B, PFJ‐W and PFJ‐G) and frozen (PFJ‐BF, PFJ‐WF and PFJ‐GF) PFJs were examined. Frozen PFJs were prepared by freezing fresh PFJs at −22°C with 20% glycerol (v/v). Treatments of lucerne silage included (1) control; (2) silage treated with PFJ‐B; (3) silage treated with PFJ‐W; (4) silage treated with PFJ‐G; (5) silage treated with PFJ‐BF; (6) silage treated with PFJ‐WF; and (7) silage treated with PFJ‐GF. All the treatments consisted of five replicate silos, and they were prepared in 1·0‐L glass jar silos. Results showed that silages treated with fresh and frozen PFJs, regardless of plant material, had better fermentation quality than the control silage in terms of lower pH, butyric acid (BA) and ammonia nitrogen (NH3‐N) concentrations, as well as higher lactic acid (LA) concentration (P < 0·05) and in vitro organic matter digestibility (IVOMD), metabolizable energy (ME) content, and gas production values (P < 0·05). Results indicated that PFJ treatments enhanced the nutritive value, fermentation quality and IVOMD, ME content and gas production values of first‐cut lucerne silages.

The Effects of Different Silage Additives on in vitro Gas Production, Digestibility and Energy Values of Sugar Beet Pulp Silage

The Effects of Different Silage Additives on in vitro Gas Production, Digestibility and Energy Values of Sugar Beet Pulp Silage

In vitro rumen fermentation: Effect of headspace pressure on the gas production kinetics of corn meal and meadow hay

An automated batch system, consisting in 20 bottles equipped with gas pressure sensors and venting valves, was used to test the effects of headspace pressure on the kinetics of gas production (GP). Two venting procedures were compared: with FT (fixed times) the gas accumulated in the headspace of bottles was released after 2, 4, 6, 8, 12, 24, 48, 72 and 144 h of incubation, whereas with FP (fixed pressure) the valves were opened at a threshold of 3.4 kPa. For each procedure, samples of corn meal and meadow hay (0.50 g) were incubated in 4 replications in 310 ml bottles with 25 ml of rumen fluid and 50 ml of medium for 144 h at 39 ◦C. Both with FT and FP, gas pressures at the times of venting, converted in terms of volumes, were adjusted or not for the amount of dissolved gas according to the Henry’s law. Data were cumulated and they were best fitted by a first order model the which parameters are the asymptotic GP (A), the time at which half of A is produced (T½) and the sharpness (c) of the curve. The effects of the 2 procedures were evaluated using a Wilcoxon twosample test. The headspace pressure obtained with FT peaked 18.0 ± 2.84 kPa at 12 h on corn, while peaked 7.5 ± 0.81 kPa at 48 h on hay. For corn, the un-adjusted GP achieved between 12 and 48 h of incubation were 21 and 8% lower with FT compared to FP (P=0.01), and FT also had greater standard deviations. A similar trend, less accentuated, was observed for hay. The T½ values were greater with FT compared to FP (+1.3 and +2.3 h, for corn and hay, respectively; P<0.05), suggesting that FT delayed the release of gas dissolved in the medium. After adjustment, the GP values provided by the 2 procedures continued to be different for corn: compared to FP, FT reduced GP at 12, 24 and 48 h (P=0.01). Adjustments removed all the differences for hay due to the venting procedure. Using the FT procedure, headspace volume, venting frequency and amount of fermentable matter must be carefully balanced to avoid high headspace pressures, lowered gas release and, hence, altered GP kinetics.

In vitro rumen fermentation kinetics and nutritional evaluation of Kochia indica as affected by harvest time and cutting regimen

Branches of Kochia indica were hand-cut after 60, 90 and 120 days of planting (DAP) at 15 or 30 cm distance from the tip (cutting length). The plants were at a vegetative stage for 60 and 90 DAP, while, for 120 DAP, they were at flowering stage. The nutritive value of the experimental plant samples was evaluated by determination of the crude protein (CP), buffer soluble nitrogen (BS-N), buffer soluble non-protein nitrogen (BS-NPN) and cell wall constituents (neutral-detergent fiber; aNDF, acid-detergent fiber; ADF and lignin (sa)). In vitro digestible organic matter (IVDOM), metabolizable energy (ME), microbial nitrogen (MN) and biomass (MBM) production were also estimated in the experimental samples after their incubation with rumen fluid for 96 h in the absence or presence of polyethylene glycol. The characteristics of fermentation (initial gas production; a, gas production during incubation; b, potential gas production; a + b, fractional rate of gas production; c) were assessed using an in vitro incubation technique with rumen fluid. There was a negative effect of harvest time on all the studied nutritive parameters and fermentation characteristics. The values of CP, BS-N, BS-NPN, MN and MBM declined and concentrations of aNDF, ADF and lignin (sa) increased between early harvest time after 60 DAP and late harvest time after 120 DAP and between cutting length at 15 cm and 30 cm ( P<0.05). IVDOM were positively correlated with BS-N and BS-NPN but negatively correlated with aNDF and ADF. Cutting treatments negatively affected all the studied nutritive parameters and fermentation rates. There were no differences in the values of IVDOM, ME, MN, MBM, fermentation characteristics and gas production over 96 h due to add of PEG ( P<0.05). The greatest proportion of gas production occurred between 6 and 24 h of incubation. C values were negatively correlated with cell wall constituents but positively correlated with CP, BS-N, BS-NPN, MN and MBM. The amount of MN produced from 100 mg substrate amounted to 1.9 or 1.4 mg at early maturity stage and 1.1 or 0.8 mg at late stage for cutting lengths performed at 15 or 30 cm, respectively. Microbial nitrogen and MBM production were negatively correlated with cell wall constituents and gas production but positively correlated with CP, BS-N and BS-NPN. Results revealed that, the harvested branches of K. indica at the vegetative stage were better in terms of nutritional value than those harvested at flowering stage.

Recovery of Turkish Oil Shales by Electromagnetic Heating and Determination of the Dielectric Properties of Oil Shales by an Analytical Method

The effect of microwave irradiation on the recovery of three different oil shale samples was studied. To enhance the microwave efficiency, three different iron powders (Fe, Fe2O3, and FeCl3) and their three different doses (0.1, 0.5, and 1% by weight, each) were added to the samples as microwave receptors. The doses of each receptor were optimized for each oil shale sample based on the highest oil or gas production value obtained experimentally. During the experimental studies, the temperature distribution and the emissions of CO, H2S, CH4, and O2 gases were recorded. Temperature distributions obtained experimentally were modeled analytically to find the microwave power absorption coefficient of each oil shale sample. Experimental and analytical studies show that, oil recovery from oil shales is not only related to reaching the pyrolysis temperature, but also to the amount of time that temperature is maintained. Therefore, for the efficient recovery of oil shales, the best solution is found in a hybrid ut...

Effect of mannanoligosaccharides supplementation on caecal microbial activity of rabbits

A total of 200 weaned (35 days) hybrid Hyla rabbits were randomly divided among five groups housed in bicellular cages (20 cages per group). Between 35 and 60 days of age, the groups were submitted to the following treatments: group ANT (positive control) fed a basal diet supplemented with antibiotics (colistin sulphate, 144 mg/kg; tylosin, 100 mg/kg; and oxytetracyclin, 1000 mg/kg); groups MOS_0.5, MOS_1.0 and MOS_1.5 fed the basal diet supplemented with 0.5, 1.0 and 1.5 g/kg mannanoligosaccharides (MOS), respectively; another group fed the basal diet without antibiotics or mannanoligosaccarides supplementation (negative control). Along the trial, an episode of epizootyc rabbit enteropathy occurs so that in the control group mortality rate was very high (78%) and survivor rabbits showed severe symptoms of disease (diarrhoea). Thus, the control group was discarded from the trial. At 60 days of age, samples of caecal content were collected from 10 rabbits per group and used as inocula for an in vitro gas production trial. At the end of fermentation (120 h of incubation), organic matter digestibility (OMd), cumulative gas production, fermentation kinetics, pH, volatile fatty acid (VFA) and NH3 productions were measured. Inoculum from MOS_1.0 rabbits showed the significant higher values of OMd (64.21%, P < 0.05), gas production (262.32 ml/g, P < 0.05), acetate (96.99 mmol/g OM, P < 0.05) and butyrate (26.21 mmol/g OM, P < 0.05) than the other groups. Slight differences were recorded among the groups ANT, MOS_0.5 and MOS_1.5. In addition, branched chain acids, in proportion to total VFAs, were significantly higher in MOS_1.0 inoculum (0.04, P < 0.05). MOS are able to affect fermentation activity of caecal micro-organism, but their activities seem not proportional to their level in the diet.

Fractionation of pea flour with pilot scale sieving. II. In vitro fermentation of pea seed fractions of different particle sizes

Pea seeds were ground through a 4 mm-screen and then dry sieved. The resulting nine particle size fractions were characterised chemically (crude protein, cell walls fractionation, starch and ash) and physically (granulometric profile, specific surface area, total porous volume and apparent density) and then fermented in vitro using an adaptation of the gas-test method. The fermentation evolutions of the fractions were studied using a gas-test method at the incubation times of 0, 2, 4, 6, 8, 12, 24 and 48 h. Cumulative gas production was recorded and pH, soluble carbohydrate (SC) and ammonia (NH 3) concentrations were determined in the supernatant. As pea particle sizes became finer, the rates of gas production increased (from 2.1 ml/h for the coarsest to 7.0 ml/h for the finest fractions, after 8 h of incubation), while pH and SC concentration decreased. Rate of production of NH 3 was higher for the smallest particles in the short term, but increased linearly for the coarsest fractions. The values of cumulative gas production, pH, SC and NH 3 at different times were better explained by chemical rather than by physical criteria. Correlation analyses indicated that lignocellulose was the best chemical predictor of cumulative gas production, pH and SC, while crude protein was the best one for NH 3. Among the physical criteria, the median diameter, and to a lesser extent the specific surface area were found to be the best related to the variations of the cumulative gas production, of the pH, of NH 3 or SC concentrations in the syringes. In the present work, pea particle size was found to have a strong influence on degradation rate and probably on microbial activity. Although the chemical and physical characteristics of the pea fractions explained a large part of the results, it was, however, not possible to separate clearly the respective influences of chemical and physical parameters on particle fermentation.

Effects of corn processing method in diets containing sorghum wet distillers grain plus solubles on performance and carcass characteristics of finishing beef cattle and on in vitro fermentation of diets

Two randomized complete block design experiments with a factorial arrangement of treatments were conducted to study the effects of corn processing method and inclusion of sorghum wet distillers grain plus solubles (SWDGS) in beef cattle finishing diets. In Exp. 1, 160 crossbred steers (primarily British x Continental breeding; initial BW = 397.6 +/- 29.4 kg) were fed diets based on dry-rolled (DRC) or steam-flaked corn (SFC), with or without the inclusion of 15% SWDGS (DM basis). Corn processing x SWDGS interactions were not detected (P > or = 0.20) for performance and most carcass characteristics. The G:F was less (P < 0.01) with DRC- than with SFC-based diets. Steers fed SFC-based diets had greater 12th-rib fat thickness (P = 0.03), yield grade (P = 0.02), and a smaller LM area (P = 0.08) than steers fed DRC. Inclusion of 15% SWDGS resulted in decreased G:F (P < 0.01) than for diets without SWDGS. In addition, steers fed SWDGS had decreased HCW (P = 0.01) and dressing percent (P = 0.03) than those fed no SWDGS. In Exp. 2, diet samples from Exp. 1 were used to evaluate rate of in vitro gas production, IVDMD, and H(2)S concentrations in gas. No significant corn processing x SWDGS interactions were noted for any of these measurements or for mathematically fitted gas production parameters, except for the predicted maximum value of gas production. The SFC-based diets had greater IVDMD (P = 0.01), area under the gas production curve (AUC; P = 0.02), and rate (k) of gas production (P = 0.02) than DRC-based diets. Inclusion of 15% SWDGS in the substrates decreased IVDMD (P < 0.01), AUC (P = 0.03), and rate of gas production (P = 0.04) compared with 0% SWDGS. Hydrogen sulfide concentrations in gas did not differ (P > 0.10) with corn processing method or addition of SWDGS. Overall, these data suggest that the response to 15% SWDGS in finishing diets was not affected by corn processing method, but including 15% SWDGS in finishing diets decreased G:F, IVDMD, and gas production AUC values to approximately the same extent as replacing SFC with DRC.

An in vitro nutritive evaluation and rumen fermentation kinetics of Sesbania aculeate as affected by harvest time and cutting regimen

The nutritive value of Sesbania aculeate harvested after 60 and 120 days of planting and subjected to two cutting regimen (15 or 30 cm length) was evaluated by determination of the crude protein (CP), crude fibre (CF), buffer soluble nitrogen (BS-N), buffer soluble non-protein nitrogen (BS-NPN) and cell wall constituents (neutral-detergent fibre; NDF, acid-detergent fibre; ADF and lignin). In vitro digestible organic matter (IVDOM), metabolizable energy (ME), microbial nitrogen (MN) and biomass (MBM) production were also estimated in the experimental plant samples after their incubation with rumen fluid for 96 h in the absence or presence of polyethylene glycol (PEG, 6000) at a ratio of 2:1 PEG:substrate. Fermentation characteristics (initial gas production; a, gas production during incubation; b, potential gas production; a+b, fractional rate of gas production; c) were assessed using an in vitro incubation technique with rumen fluid. There was a significant (P < 0.05) effect of harvest time on all studied nutritive parameters and fermentation characteristics. The early harvest plant samples (after 60 days of planting) gave significantly higher values of IVOMD, ME, CP, BS-N, BS-NPN, MN, MBM and fractional rate of gas production and lower values of CF and cell wall constituents than the late harvest. Crude protein, BS-N, BS-NBN, IVOMD and ME were negatively correlated with CF and cell wall constituents. Metabolisable energy and IVOMD were positively correlated with CP, BS-N and BS-NPN. Cutting treatments significantly affected the CP, CF, BS-N, BS-NPN, NDF, ADF, IVDOM, ME, potential gas production and b values. There was no significant (P > 0.05) effect of added PEG on IVDOM, ME, MN, MBM, fermentation characteristics and gas production over 96 h. The greatest proportion of gas production occurred between 6 and 24 h of incubation. The fractional rate of gas production from 100 mg substrate was higher (0.046 mL/h) for the plant samples harvested at early stage and cut at 30 cm length than harvested at late stage (0.018 mL/h). C values were negatively correlated with lignin concentrations. The amount of MN and MBM produced from 100 mg substrate amounted to 1.29 mg and 14.95 mg at early maturity stage and 0.68 mg and 7.89 mg at late stage, respectively. Microbial nitrogen and MBM production were negatively correlated with CF, cell wall constituents and gas production but positively correlated with CP, BS-N and BS-NPN.

Effects of water extracts from chicory and BHT on the in vitro rumen degradation of feeds

Effects of Butyl-Hydroxyl-Toluene (BHT) and of Red Chicory Extract (RCE) on kinetics of gas production (GP) and rumen degradability values (OMd, NDFd and in vitro true OM degradability - IVTOMD) of two feeds (meadow hay and corn meal) were evaluated using an in vitro automatic batch system. For each feed 2 increasing dosages (0.15 and 1.5 mg/g of feed) of BHT and RCE and a Control (C) were tested in 4 replications and 2 incubations. First incubation lasted 72h, the 2nd one was stopped at the times on which half of GP was produced (t½), which were 9 and 16 h for corn and hay, respectively. From the supernatants of the 2nd incubation, VFA, NH3, N content of the residual NDF were analysed and the microbial N balance was computed. The 2 feeds significantly affected rumen fermentation parameters; BHT significantly increased asymptotic GP, t½ and IVTOMD (P<0.01), decreased the proportion of butyrate (P<0.01) but did not affect microbial N balance; RCE did not influence any of the parameters measured with respect to C, except for a significant increase of the estimated N available for microbes at the higher dosage.

Esansiyel Yağların Sindirim, Rumen Fermantasyonu ve Mikrobiyal Protein Üretimi Üzerine Etkileri

Summary The objective of this study was to determine the effect of inclusion of oregano oil (OrO), peppermint oil (PO) and orange oil (OO) in the ratio of 0, 400, 800 and 1200 mg/lt into rumen fluid on the gas production, organic matter digestibility (OMD) and metabolizable energy (ME), rumen fermentation characteristics and microbial protein production using the in vitro gas production technique. The inclusion of OrO, PO and OO in a different level significantly (P<0.05; P<0.01) decreased the in vitro gas production, OMD and ME values. The inclusion of essential oil decreased the total volatile fatty acids (VFA), acetic acid, propionic acid, butyric acid, acetic acid/ propionic acid ratio and ammonia level whereas the inclusion increased the rumen pH. In addition, the inclusion of oregano oil significantly (P<0.05; P<0.01) decreased carbon dioxide (CO2), methane (CH4) and microbial protein production (MPP). The OrO was the most effective essential oil when all parameters were taken into consideration, followed by PO and OO. The inclusion of OrO in the ratio of 1200 mg/lt has been found to be the most effective doses and a negative impact on the data obtained. In conclusion, it can be said that low doses of essential oils should be used in ruminant nutrition but high doses of essential oils may decrease the rumen function and feed efficiency.

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.

Determining Nutritive Values of Alfalfa Cuts Using in situ and Gas Production Techniques

In order to determine of nutritive value of alfalfa in different cuts using in situ and gas production technique, this study was carried out. Three wethers (49±2.6 kg) were used in in situ method. The gas production was measured at 2,4,6,8,12,16,24,36,48,72 and 96 h and ruminal dry matter and crude protein disappearance were measured at 0,4,8,12,16,24,36,48,72 and 96 h. Dry matter degradability’s in first, second and third cuts of alfalfa at 96 h were 60.47, 64.71 and 64.36%, respectively. Crude protein degradability’s of mentioned cuts were 60.47, 63.08 and 58.07%, respectively. The gas productions of them at 96 h were 322.54, 295.21 and 300.32 mL g−1 DM respectively. The relationship between dry matter and gas production values for alfalfa cuts obtained about 0.89, 0.85 and 0.84 and for crude protein and gas production data achieved 0.87, 0.88 and 0.84, respectively. High correlation between in situ and gas production techniques indicated that in situ degradability’s values can be predicted from gas production data.

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.

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.

Early growth and seasonal chemical composition of three indigenous multipurpose tree species (MPTS) in Abeokuta, Nigeria

A study was carried out to evaluate the growth parameters and nutritive qualities of Moringa oleifera, Millettia griffoniana and Pterocarpus santalinoides. The main objective of the study was to assess the potential of the MPTS in supplementing the feed of ruminant animals during the dry season when grasses are scarce and their quality generally fall short of animal requirements. Leaf samples were randomly collected from the trees for estimation of the proximate composition, neutral detergent fibre, acid detergent fibre and gas production using the in vitro technique. Samples were collected three times to represent seasonal variations as follows: November: Early Dry; February: Mid Dry and April: Late Dry seasons. Gas production was recorded at 3, 6, 9, 12, 15, 18, 21, 24, 48, 72 and 96 h of incubation. Mortality rate was less than 5%. M. oleifera recorded the best overall growth respectively followed by P. santalinoides and M. griffoniana. P. santalinoides and M. oleifera retained more leaves in the dry season than M. griffoniana. The dry matter (DM) and ether extract (EE) contents of the MPTS were significantly (P < 0.05) affected by seasons and plant species while there were significant (P < 0.05) species effects on the CP and ADF values. The gas production values and the fermentation parameters indicated the presence of potentially degradable nutrients in the MPTS, which underscores the importance of the tree species as sources of nutrient for ruminant animals during the dry season.

Management: The High-Tech World of Testing

Driven by mounting pressure to reduce E&amp;P risk, the testing techniques introduced by brothers E.C. and M.O. Johnston in the 1920s are mounting a revival. But they bear little resemblance to those early days when simple downhole tools were run and the only measurements consisted of examining the produced fluids. Often characterized by large amounts of piping and heavy equipment, testing has become high-tech and makes use of the most sophisticated types of metrology available. Today, testing results can be delivered in near-real time. Results are highly accurate and integrate seamlessly with comprehensive, dynamic reservoir models that benefit from the aggregate of exploration, drilling, formation evaluation, and production data. In reality, a test involves a pressure sensor of the right resolution and accuracy put in the right place and left for the right amount of time. The trick, of course, is in the determination of what is "right," and that involves a deep understanding of the reservoir as well as flow dynamics and fluid mechanics. Absent these qualities, a test can be deemed a "successful failure"—meaning one where all the valves, chokes, separators, tanks, and gauges work properly, but the data are ambiguous and inconclusive. Today, operators simply cannot risk getting it wrong. For example, if a subsea system or a floating production facility is installed that is either too large or too small or because production was incorrectly predicted, the cost can be ruinous. The risks of drilling and completing wells have grown exponentially, as have the potential values of oil and gas production. Modern testing minimizes those risks to the maximum. Plumbers No More While hooking up myriad valves, pipes, and tanks to separate fluids into three phases (oil, gas, and water) in order to make flow measurements worked in earlier times, it cannot solve today's challenges. In the past, the industry's appreciation of testing was gauged by the amount of steel involved. Today, high-speed sensors resolve multiphase flow that often includes gas and condensate. Operators need solid information on which to base critical decisions, and they want details on today's well conditions, as well as an accurate view of the future. Answers must address life-of-the-reservoir issues. Much of the technology to support these solutions is available, but more development is needed. Two areas in which high technology is playing a major role are multiphase flowmetering and fast pressure/volume/temperature (PVT) analysis. Portable on-site well fluid analysis services are now available that can be set up at the wellsite in minutes and provide key fluid parameters that figure in the operator's production decisions. Essential for evaluating the profitability of the prospect, fluid composition and physical properties from samples collected at the well-head impact completion and production facility design. Compositional analysis to C12 for gas and C36 for oil provides key input for reservoir and equations-of-state simulators. Results can now be derived, verified, and presented, usually before the testing crew has rigged down. Besides enabling near real-time-quality control, data from the on-site PVT analysis are used to optimize multiphase flowmeter measurements.

In vitro Parameters as Predictors of Metabolizable Energy Values of Roughages

Ozkul, H., Sayan, Y., Polat, M. and Kilic, A. 2007. In vitro parameters as predictors of metabolizable energy values of roughages. J. Appl. Anim. Res., 31: 85–88. To predict the metabolizable energy (ME) values of roughages based on in vitro 24h gas production (GP) with cell wall contents and I or chemical components, data of Sayan et al. (2004) for 40 roughages were used in the study. Based on R2 (determination coefficient) values, best predictions were made when GP and ADF values were used with crude protein, ash and ether extract separately or together.

A comparison of Khuff and Arab reservoir potential throughout the Middle East

A compilation of average porosity and permeability data for petroleum reservoirs in the Permian–Triassic Khuff Formation and the Jurassic Arab Formation shows that most Khuff reservoirs have an average porosity of less than 12%, whereas most Arab reservoirs have an average porosity of 12–26%. Higher porosity correlates with shallower depth, suggesting that burial diagenesis is the main cause of the overall porosity difference between these units. Deeper burial of Khuff reservoirs is inferred to have resulted in greater porosity loss by chemical compaction and associated cementation. A broad correlation also exists between average porosity and average permeability, suggesting that deeper burial and the resulting porosity decrease are also a primary cause of the lower permeabilities of the Khuff reservoirs. In addition to greater burial depth, however, a combination of depositional and early diagenetic factors is also reflected in the lower average porosity and permeability values of the Khuff reservoirs. Khuff strata were deposited on an extensive, poorly circulated, very low-relief shelf and consist in large part of interbedded mudstones and grainstones having relatively fine grain size, with major amounts of depositional calcium sulfate present. Arab reservoirs were deposited under better circulated conditions near platform margins facing deep, intracratonic basins and, thus, have coarser, more grain-dominated fabrics and lesser overall content of chemically precipitated grains, calcium sulfate, and dolomite. Khuff deposits were likely composed of less stable mineralogy than Arab sediments because the Late Permian was a time of aragonite seas, whereas the Late Jurassic was a time of calcite seas. The combined result of these factors is that Arab reservoirs are characterized by greater preservation of primary depositional pore types, more coarsely crystalline dolomite fabrics, and lesser plugging by anhydrite. Finally, a possible factor affecting the average porosity and permeability values is petroleum composition, which is gas in most Khuff reservoirs and oil in Arab reservoirs. Lower economic cutoff values for gas production would favor inclusion of low-permeability zones in Khuff reservoirs, thus reducing average reservoir values. Two main aspects of these results are innovative. This is the first time that porosity and permeability values for either Khuff or Arab reservoirs have been examined regionally. Second, the conclusion that thermal exposure is the primary control on average porosity and permeability in these units is consistent with previous work from other carbonates, but is new for the Middle East.