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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

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Chemical composition and in vitro total gas and methane production of forage species from the Mid Rift Valley grasslands of Ethiopia
Bezabih, M. ; Pellikaan, W.F. ; Tolera, A. ; Khan, N.A. ; Hendriks, W.H. - \ 2014
Grass and Forage Science 69 (2014)4. - ISSN 0142-5242 - p. 635 - 643.
feed-intake - production profiles - southern ethiopia - detergent fiber - ruminant feeds - zebu cattle - rumen fluid - fermentation - protein - degradability
There is increasing interest in sustainable land use in the tropics to optimize animal production while also reducing methane (CH4) emissions, but information on nutritive value and CH4-emission potential of tropical forage species is limited. Samples of 24 grasses and five other forages were collected during the main rainy season on randomly positioned quadrats in semi-arid grassland in the Mid Rift Valley of Ethiopia. Samples were pooled by species, analysed for chemical composition and incubated with rumen fluid to determine total gas and CH4-emission potentials using a fully automated in vitro gas production apparatus. Organic matter digestibility (OMD) and metabolizable energy (ME) contents were calculated from chemical composition and gas production data. Large variability was observed among forages for all nutritional variables considered. The grasses Eleusine multiflora, Pennisetum stramineum, Dactyloctenium aegyptium, Eragrostis aspera, Cenchrus ciliaris and Eragrostis cilianensis showed relatively high OMD (68–72%) and ME values (9 1– 10 2 MJ kg 1 dry matter). Melinis repens, E. multiflora and the non-legume forb Zaleya pentandra showed relatively low CH4 to total gas ratios; these species may have potential for use in low CH4-emission forage diets. Acacia tortilis fruits had high content of crude protein and moderate ME values, and may be an ideal feed supplement for the grazing ruminant. Sodium content was below the recommended level for ruminants in all the forage species. Overall, the pasture stand during the main growing season was evaluated as having moderate nutritional quality.
Fermentation kinetics and production of volatile fatty acids and microbial protein by starchy feedstuffs
Cone, J.W. ; Becker, P.M. - \ 2012
Animal Feed Science and Technology 172 (2012)1-2. - ISSN 0377-8401 - p. 34 - 41.
gas-production technique - rumen fluid - production profiles - ruminant feeds - dairy-cows - milk-yield - in-situ - degradability - degradation - sheep
The rate and extent of rumen fermentation of different starch sources can be very different, depending on the origin of the starch, but more importantly on the technological treatment of the starchy feed ingredients. Therefore, feeding different starchy feed ingredients can contribute in a very different way to the total volatile fatty acid (VFA) production in the rumen, the proportion of each VFA, and the non-glucogenic to glucogenic ratio (NGR). For 14 different starchy feed ingredients, the in vitro fermentation characteristics were determined using the gas production technique. Highest rate and extent of gas production was seen for the popped feedstuffs, while lowest was seen for the native starch sources maize and potato. This was also reflected in the rate of production of individual and total VFA. However, after 12 h of fermentation, differences in VFA content decreased and VFA production reflected the total fermentation of the organic matter. It proved that for the determined incubation periods (4, 8 and 12 h), there was a negative linear relationship (R2 = 0.33–0.79) between NGR and the amount of gas produced. There was also a negative linear relationship (R2 = 0.75) between the synthesized amount of microbial protein and the rate of fermentation at the incubation period at which the substrate was just exhausted (tRmax2). This shows that fast fermenting substrates resulted in a higher amount of microbial protein than slowly fermenting substrates. Consequently, there was also a negative linear relationship (R2 = 0.64) between the amount of microbial protein and NGR at tRmax2. It is concluded that fast fermenting starchy feedstuffs resulted in higher amounts of microbial protein in the rumen and a more glucogenic fermentation pattern, higher values of propionic acid and lower values of acetic acid and butyric acid. Abbreviations - A1, gas production caused by fermentation of the soluble fraction; A2, gas production caused by fermentation of the non-soluble fraction; B2, time needed for 0.5 of A2; C2, parameter determining the shape of the gas production sub-curve caused by fermentation of the non-soluble fraction; DM, dry matter; HAc, acetic acid; HB, butyric acid; HP, propionic acid; MP, microbial protein; NGR, non-glucogenic to glucogenic ratio; OM, organic matter; R2, fractional rate of substrate fermentation of the non-soluble fraction; RNA, ribonucleic acid; SD, standard deviation; tRmax2, time at which R2 is at its maximum; VFA, volatile fatty acids
A novel method to determine simultaneously methane production during in vitro gas production using fully automated equipment
Pellikaan, W.F. ; Hendriks, W.H. ; Uwimanaa, G. ; Bongers, L.J.G.M. ; Becker, P.M. ; Cone, J.W. - \ 2011
Animal Feed Science and Technology 168 (2011)3-4. - ISSN 0377-8401 - p. 196 - 205.
rumen microbial fermentation - essential oils - production profiles - condensed tannins - ruminant feeds - dairy-cows - kinetics - nitrogen - nutrition - invitro
An adaptation of fully automated gas production equipment was tested for its ability to simultaneously measure methane and total gas. The simultaneous measurement of gas production and gas composition was not possible using fully automated equipment, as the bottles should be kept closed during the incubations. A separate small opening with a screw cap and septum was made in each bottle, making it possible to take very small aliquots (10 µl) from the gas in the headspace with a syringe for immediate gas analysis. As the used automatic gas production equipment was a venting system, corrections had to be made for the vented total gas and methane, as well as for the dilution of the produced methane with the gas in the headspace. To test the suitability and accuracy of the system, known amounts of methane were injected in bottles in the venting system and methane concentrations in the headspace were determined. It proved that the methane concentration in the headspace, corrected for the vented gas, coincided with the injected amount of methane. To show the potency of the adapted equipment, experiments were conducted with different feedstuffs. Total gas production and methane production were recorded and their relationships were calculated. The ability of the system to test feed additives for methane reduction was demonstrated for maize and soybean hulls as substrate (0.5 g DM), supplemented with monensin (15 mg), sodium-2-bromoethanesulphonate (BES, 15 mg), cinnemaldehyde (150 mg) and tea tannins (150 mg), additives known to effect methane synthesis. The adapted gas production equipment showed to be a powerful tool to determine rate and extent of gas production as a measure of fermentation and to simultaneously determine methane production.
Assessing fibre-rich feedstuffs in pig nutrition: comparison of methods and their potential implications
Sappok, M.A. ; Pellikaan, W.F. ; Verstegen, M.W.A. ; Sundrum, A. - \ 2009
Journal of the Science of Food and Agriculture 89 (2009)15. - ISSN 0022-5142 - p. 2541 - 2550.
total tract digestibility - in-vitro fermentation - volatile fatty-acids - gas-production - microbial activity - stomached animals - large-intestine - ruminant feeds - dietary fiber - growing pigs
BACKGROUND: In organic farming, roughage has to be added to pigs' daily rations for animal welfare reasons. Since little is known about how roughage affects pigs, seven carbohydrate-rich feedstuffs (corn silage, ryegrass, turnip leaf, turnip tuber, Jerusalem artichoke and two types of clover-ryegrass silage) were tested using two different in vitro methods - total tract digestibility and the gas production technique - to determine apparent digestibility by observing organic matter loss. The aim was to determine whether the results of different methods and treatments lead to similar results or rankings. RESULTS: The in vitro enzymatic incubation method showed 3-20% lower fermentabilities than the in vitro fermentation process. The pretreatment of substrates with enzymes before fermentation led to similar fermentabilities but different gas production kinetics compared to the fermentation of untreated substrates. Using two different inocula generated no significant differences. When the feedstuffs were ranked by their fermentability, the rank order was relatively similar for both methods. CONCLUSIONS: Different methods and pretreatments lead to different fermentabilities while a ranking of the results gives a similar order. Both methods seem to be appropriate tools for assessing feedstuffs. In order to determine which feedstuff is best utilised by the animal, further investigations of both digestibility and gas production kinetics are required
Relationship between in situ degradation kinetics and in vitro gas production fermentation using different mathematical models
Rodrigues, M.A.M. ; Cone, J.W. ; Ferreira, L.M.M. ; Blok, M.C. ; Guedes, C. - \ 2009
Animal Feed Science and Technology 151 (2009)1-2. - ISSN 0377-8401 - p. 86 - 96.
nylon bag degradability - production profiles - ruminant feeds - rumen fermentation - dairy-cows - extent - fluid - digestibility - disappearance - prediction
In vitro and in situ studies were conducted to evaluate the influence of different mathematical models, used to fit gas production profiles of 15 feedstuffs, on estimates of nylon bag organic matter (OM) degradation kinetics. The gas production data were fitted to Exponential, Logistic, Gompertz and a Sigmoidal model. Using only gas production parameters allowed poor prediction of in situ degradation. It was not possible to estimate the washout (W) and degradable (D) in situ fractions for all models, with the exception of the Sigmoidal model with which the D fraction was poorly estimated (R2 = 0.28). The Exponential model did not show any estimation capability, and the Logistic and Gompertz models best predicted in situ degradation rate of OM (kd) with R2 values of 0.65 and 0.62, respectively. The transformation of the in situ rate of degradation (kd) to its half-life value of degradation ((ln 2/kd)100) provided an improvement of kd prediction in the Sigmoidal model, with R2 changing from 0.35 to 0.64. As to kd and fermentable organic matter (FOM) all estimations improved upon inclusion of chemical composition characteristics, such as sugars, crude protein (CP), neutral detergent fibre (NDFom) and crude fat (CFat). The Logistic and Gompertz models continued to better predict kd, with R2 values of 0.79 and 0.88, respectively, while the Sigmoidal model showed a higher capability to estimate FOM (R2 = 0.90). It should also be noticed that the estimation of the washout fraction (W) estimation was obtained with only sugar and starch contents (R2 = 0.62). There were only moderate relationships between in situ and gas production indicating that the methods do not describe the degradation of these feedstuffs in a similar way
Differences in Microbial Activities of Faeces from Weaned and Unweaned Pigs in Relation to In vitro Fermentation of Different Sources of Inulin-type Oligofructose and Pig Feed Ingredients
Shim, S.B. ; Verdonk, J.M.A.J. ; Pellikaan, W.F. ; Verstegen, M.W.A. - \ 2007
Asian-Australasian Journal of Animal Sciences 20 (2007)9. - ISSN 1011-2367 - p. 1444 - 1452.
dietary nondigestible oligosaccharides - growing pigs - bacterial fermentation - gastrointestinal-tract - large-intestine - ruminant feeds - fructooligosaccharides - performance - microflora - prebiotics
An in vitro experiment was conducted to evaluate the differences in microbial activity of five faecal inocula from weaned pigs and one faecal inoculum from unweaned pigs in combination with 6 substrates. The substrates tested were negative control diet, corn, soybean meal, oligofructose (OF), ground chicory roots and a mixture (60% chicory pulp and 40% OF). The inocula used were derived from pigs fed either a corn-soy based diet without antibiotics (NCON), the NCON diet supplemented with oligofructose (OF), a mixture of chicory pulp (40%) and OF (60%) (MIX), ground chicory roots (CHR) or the NCON diet supplemented with antibiotics (PCON). The cumulative gas production measured fermentation kinetics and end products, such as total gas production, ammonia and volatile fatty acids, were also determined. Both the substrate and the inoculum significantly affected the fermentation characteristics. The cumulative gas production curve showed that different substrates caused more differences in traits of fermentation kinetics than the different inocula. Inocula of weaned pigs gave a significantly higher VFA production compared to the inoculum from unweaned animals, whilst the rate of fermentation and the total gas produced did not differ. OF showed the highest fermentation kinetics and the lowest NH3, pH and OM loss compared to other substrates. It was concluded that the microbial activity was significantly affected by substrate and inoculum. Inoculum from weaned pigs had more potential for microbial fermentation of the carbohydrate ingredients and oligofructose than that of unweaned pigs. A combination of high and low polymer inulin may be more beneficial to the gut ecosystem than using high- or low-polymer inulin alone.
Voluntary intake of silages in dairy cows depending on chemical composition and in vitro gas production characteristics
Hetta, M. ; Cone, J.W. ; Bernes, G. ; Gustavsson, A.M. ; Martinsson, K. - \ 2007
Livestock Science 106 (2007)1. - ISSN 1871-1413 - p. 47 - 56.
rumen fermentation characteristics - nylon bag degradability - neutral detergent fiber - grass-silage - production profiles - ruminant feeds - food-intake - red-clover - prediction - digestion
A study was conducted to investigate the possibilities to develop models for predicting the relative silage dry matter intake (SDMI) in dairy cows utilising information on chemical composition and in vitro gas production (GP) kinetics of silages. In five experiments, each with an average of 38 lactating dairy cows, SDMI was recorded for 15 grass silages made from primary growth and regrowth swards of timothy (Phleum pratense L.). The silages were characterised by chemical analysis and by utilising an automated in vitro GP recording technique with end point measurements of substrate residues. The silage samples were analysed both as dried and wet samples to evaluate the effects of sample preparation techniques on GP kinetics and their relations to SDMI. Relationships between feed variables and SDMI were investigated utilising simple linear and multiple regression. The wet silage samples had higher cumulative GP and different GP curves compared to the dried samples. The linear relationships between, GP variables, harvest number (first or second cut) of the grass, chemical characteristics of the silages and the relative SDMI show that the GP technique is a powerful tool to detect silage quality. By using the parameters from the dried samples the multiple regression analysis resulted in a relationship, relative SDMI (kg per 100 kg live weight (LW)) per day=0.071+0.0029 x NDFD-0.266 x C (R-2 =0.82, S.D.=0.06). NDFD is the degradability of the neutral detergent fibre (NDF) (g/kg NDF) and C is the variable that regulates the switching characteristics of the GP profiles. By using the wet silage samples the multiple relationship did not include any GP variable; relative SDMI (kg per 100 kg LW per day) = 1.86-0.008 x acetic acid (g/kg DM) + 0.024 x ethanol (g/kg DM) (R-2=0.62, S.D.=0.08). The results from the regression analysis and the experience of the laborious sample preparation technique for wet samples, give the conclusion that dried silage samples are recommended for determining feed characteristics using the GP technique in intake studies. (c) 2006 Published by Elsevier B.V.
Some methodological and analytical considerations regarding application of the gas production technique
López, S. ; Dhanoa, M.S. ; Dijkstra, J. ; Bannink, A. ; Kebreab, E. ; France, J. - \ 2007
Animal Feed Science and Technology 135 (2007)1-2. - ISSN 0377-8401 - p. 139 - 156.
in-vitro digestibility - ruminant feeds - production profiles - chemical-composition - mathematical-models - degradation - extent - rumen - fermentation - kinetics
The in vitro gas production technique is used widely in animal nutrition for feed evaluation and to study the kinetics of microbial fermentation processes in the digestive tract. This technique is based on the assumption that gas produced in batch cultures inoculated with mixed microorganisms from ruminal or hindgut contents or faeces is directly related to the amount of substrate fermented. The technique relies on mathematical modelling to estimate the rate and extent of feed digestion from cumulative gas production profiles. Section 1 of this article deals with the application of gas laws to calculate the volume of gas produced from pressure measurements when batch cultures are incubated in gas-tight bottles. Calculation of the amount of a specific gas (methane) produced at a given incubation time from total gas production and composition is presented in Section 2. Then, the definition of specific rate of substrate degradation and that of gas production are considered. Next, a piecewise linear model based on the assumption that microbial growth and fermentation follows zero-order kinetics is derived and evaluated by comparison with other non-linear models with regard to goodness-of-fit of experimental data and estimation of rate and extent of degradation in the rumen of some feedstuffs. Finally, the possibility of using procedures to account for the inevitable cyclic trends in gas production profiles by data smoothing are discussed. All these considerations provide an insight into some of the mathematical and methodological aspects of the in vitro gas production technique and should contribute to facilitating the description and interpretation of experimental data.
The effect of sample grinding procedures after processing on gas production profiles and end-product formation in expander processed barley and peas
Azarfar, A. ; Poel, A.F.B. van der; Tamminga, S. - \ 2007
Journal of the Science of Food and Agriculture 87 (2007)5. - ISSN 0022-5142 - p. 855 - 864.
in-vitro fermentation - fatty-acid production - cumulative gas - ruminant feeds - pressure transducer - particle-size - rumen fluid - kinetics - digestion - inoculum
Grinding is a technological process widely applied in the feed manufacturing industry and is a prerequisite for obtaining representative samples for laboratory procedures (e.g. gas production analysis). When feeds are subjected to technological processes other than grinding (e.g. expander treatment), grinding afterwards may disturb the effect of processing, both in practice and when laboratory techniques are applied. Therefore, this study aimed to establish the possible effects of different grinding procedures and sample preparation on the degradative behaviour of expander processed barley and peas. Samples of expander processed barley and peas were subjected to six different sample preparation procedures (intact sample, dissolved sample, samples ground stepwise over 6 and 3 mm sieves, samples ground stepwise over 6, 3 and 1 mm sieves, samples ground over a 3 mm sieve and samples ground over a 1 mm sieve). The patterns of gas production in these samples were studied over a period of 72 h incubation using an automated in vitro gas production system. The particle size distribution determined by dry sieve analysis and the Coulter counter method changed due to the different grinding procedures. Grinding the samples of expander processed barley and peas changed the kinetics of gas production and led to a faster degradation, most pronounced after stepwise grinding. However, the formation of the fermentation end-product was not affected by the method of sample preparation. In expander processed barley, the difference in the degradation pattern due to the different grinding procedures was small.
Repeatability and reproducibility of an automated gas production technique
Laar, H. van; Straalen, W.M. van; Gelder, A.H. van; Boever, J.L. de; heer, B. D'; Vedder, H. ; Kroes, R. ; Bot, P. de; Hees, J. van; Cone, J.W. - \ 2006
Animal Feed Science and Technology 127 (2006)1-2. - ISSN 0377-8401 - p. 133 - 150.
ruminant feeds - fermentation kinetics - net carbohydrate - protein system - rumen fluid - model - degradation - profiles - invitro
Two ring tests with five and three laboratories, respectively, were conducted to quantify variation within and among laboratories in an automated gas production technique. Single batches of the feeds soya bean meal (SBM), wheat grain (WG), grass silage (GS) and maize gluten meal (MG) were divided among the participating laboratories. Gas production at defined time points and curve parameters of the mono-phasic model of Groot et al. [Groot, J.C.J, Cone, J.W., Williams, B.A., Debersaques, F.M.A., Lantinga, E.A., 1996. Multiphasic analysis of gas production kinetics for in vitro fermentation of ruminant feeds. Anim. Feed Sci. Technol. 64, 77¿99], were analysed to obtain values for within laboratory repeatability (rin: duplicate measurements) and reproducibility (Rin: among series measurements), and for among laboratory repeatability (rover: among series) and reproducibility (Rover: among laboratories) expressed as coefficient of variation (CV). For specific feeds and gas production parameters, differences in rin and Rin among laboratories occurred, showing that within laboratory repeatability and reproducibility was not the same for all laboratories. Repeatability (rover) and reproducibility (Rover) were best for fermentable organic matter (FOM), ranging from 0.4 to 2.3% and from 0.9 to 4.9%, respectively, for ring test 1. This, although not statistically testable, was better than rover and Rover for total gas production (GP72) that ranged from 2.7 to 3.9% and from 8.2 to 9.4%, respectively. Introduction of some new incubation procedures in ring test 2 reduced duplicate variation (rin) in GP72 from the range of 1.4¿10.3 to 0.2¿3.1%. This range of variation in GP72 was still numerically higher than variation in FOM, from 0.2 to 1.1%, indicating that calibration of the equipment is a source of variation. Alterations in the technique were ineffective in improving Rin, or overall repeatability and reproducibility (rover and Rover). Use of a standard feed sample to correct for between run variation within laboratory numerically decreased variation (Rin) in gas production up to 10 h (from 5 to 20% to 3 to 12.5%) and after 40 h (from 1 to 5% to 0.8 to 3%) of fermentation, but not between 10 and 40 h. Within laboratories, a level of rin for GP72 of 1¿2%, and for Rin a level of 2¿3.5% should be achievable. Use of a standard feed sample to correct for between run variation reduced Rin for GP72 to below 2%.
Use of the in vitro cumulative gas production technique for pigs: an examination of alterations in fermentation products and substrate losses at various time points1
Awati, A. ; Williams, B.A. ; Bosch, M.W. ; Li, Y.C. ; Verstegen, M.W.A. - \ 2006
Journal of Animal Science 84 (2006)5. - ISSN 0021-8812 - p. 1110 - 1118.
ruminant feeds - production profiles - large-intestine - rumen fluid - kinetics - fractions - silage
An experiment was conducted to examine changes in VFA and ammonia concentrations at different time points using 4 fermentable carbohydrate-rich feed ingredients as substrates and feces of unweaned piglets as inoculum. Fecal inoculum was collected, pooled, and mixed from 9 specially raised (no creep feed or antibiotics) crossbred piglets at 3 wk of age. Inulin, lactulose, molasses-free sugar beet pulp, and wheat starch were used as substrates and were fermented in vitro for 72 h (3 replicates per substrate). Cumulative gas production was measured as an indicator of the kinetics of fermentation. In addition, 3 bottles of substrate per time point with similar contents (amounts of substrate, inoculum, and media) were incubated but were allowed to release their gas throughout incubation. For these latter bottles, fermentation fluid was sampled at incubation time points including every hour between 1 and 24 h and at 48 h, and fermentation end products (VFA, lactate, and ammonia) and OM disappearance were measured. Dry matter and ash were analyzed from the postfermentative samples. The pH of the contents from these bottles was also recorded. The correlation in time between fermentation end products and cumulative gas produced was determined. The results showed that the prolongation of fermentation to 72 h, especially in the case of fast-fermenting inulin and lactulose, may lead to a different end product profile (P <0.001) compared with the profile observed at the time at which most of the substrate has disappeared. Therefore, we concluded that the fermentation product profile at the end of in vitro fermentation at a specific time point cannot be used to compare fermentability of carbohydrate sources with different fermentation kinetics in terms of gas production.
Prediction of forage intake using in vitro gas production methods: Comparison of multiphase fermentation kinetics measured in an automated gas test, and combined gas volume and substrate degradability measurements in a manual syringe system
Blümmel, M. ; Cone, J.W. ; Gelder, A.H. van; Nshalai, I. ; Umunna, N.N. ; Makkar, H.P.S. ; Becker, K. - \ 2005
Animal Feed Science and Technology 123-124 (2005)1. - ISSN 0377-8401 - p. 517 - 526.
ruminant feeds - rumen fluid - digestibility - degradation - roughages - quality - invitro
This study investigated two approaches to in vitro analysis of gas production data, being a three phase model with long (¿72 h) incubation times, to obtain kinetics and asymptotic values of gas production, and combination of gas volume measurements with residue determinations after a relatively short incubation of 24 h. Dry matter intake (DMI) of 24 Ethiopian forages were predicted by these approaches. Combined gas volume and true degradability measurements in vitro were used to calculate a partitioning factor (PF), being the ratio of mg substrate degraded to ml of gas produced. In the automated test, kinetics of gas production were described by a three phase model: y=a1/(1+(b1/t)c1)++a3/(1+(b3/t)c3), where y is the gas volume at time t and a1¿a3 are the volumes of gas in the pools, b1¿b3, the time when half of the gas volume of a given pool is produced and c1¿c3 describe the switching characteristics of the curves by pool. The model fitted gas production profiles, but there was no relationship between curve parameters and DMI in multiple regressions (R2 = 0.24, P=0.06). In contrast, combined gas volume and substrate degradability measurements at 24 h of incubation accounted for 63, 62 and 56% of the variation (P
Inter-laboratory variation in in vitro gas production profiles of some selected feeds, using both manual and automated methods
Rymer, C. ; Williams, B.A. ; Brooks, A.E. ; Davies, D.R. ; Givens, D.I. - \ 2005
Animal Feed Science and Technology 123-124 (2005)1. - ISSN 0377-8401 - p. 225 - 241.
temperature dried grass - neutral detergent fiber - fatty-acid production - fermentation kinetics - ruminant feeds - rumen fluid - pressure transducer - forages - degradability - degradation
A study was conducted to estimate variation among laboratories and between manual and automated techniques of measuring pressure on the resulting gas production profiles (GPP). Eight feeds (molassed sugarbeet feed, grass silage, maize silage, soyabean hulls, maize gluten feed, whole crop wheat silage, wheat, glucose) were milled to pass a 1 mm screen and sent to three laboratories (ADAS Nutritional Sciences Research Unit, UK; Institute of Grassland and Environmental Research (IGER), UK; Wageningen University, The Netherlands). Each laboratory measured GPP over 144 h using standardised procedures with manual pressure transducers (MPT) and automated pressure systems (APS). The APS at ADAS used a pressure transducer and bottles in a shaking water bath, while the APS at Wageningen and IGER used a pressure sensor and bottles held in a stationary rack. Apparent dry matter degradability (ADDM) was estimated at the end of the incubation. GPP were fitted to a modified Michaelis¿Menten model assuming a single phase of gas production, and GPP were described in terms of the asymptotic volume of gas produced (A), the time to half A (B), the time of maximum gas production rate (tRM gas) and maximum gas production rate (RM gas). There were effects (P
In vitro gas and volatile fatty acids production profiles of barley and maize and their soluble and washout fractions after feed processing
Yang, H.J. ; Tamminga, S. ; Williams, B.A. ; Dijkstra, J. ; Boer, H. - \ 2005
Animal Feed Science and Technology 120 (2005)1-2. - ISSN 0377-8401 - p. 125 - 140.
fermentation kinetics - cumulative gas - ruminant feeds - rumen fluid - dairy-cows - protein - ingredients - starch - sacco
In vitro fermentation characteristics of soluble, washout, and non-washout fractions separated from barley and maize and their technologically processed (i.e., pressure toasting, pelleting and their combination) products were measured. The aim was to establish whether the soluble equaled the washout fraction, whether these fractions are rapidly and completely fermented, and whether their fermentation characteristics are the same. A simple fractionation method was developed to separate the whole grain into a soluble fraction, a washout fraction, an insoluble washout fraction, and a non-washout fraction. Proximate analysis of the different fractions revealed in the soluble fraction a large (>400 g kg¿1 DM) residual organic matter component of unknown origin, while the insoluble washout fraction contained between 800 and 900 g starch/kg DM. Fermentation characteristics of all fractions as well as the whole grain were measured for 72 h using gas and volatile fatty acids (VFA) production in vitro. After fractionation, gas and VFA production profiles of the fractions with different chemical compositions were found to be different. Based on gas production profiles it was shown that the soluble fraction was easily fermentable and was fermented faster than the insoluble washout and the non-washout fraction. Differences were however much smaller than anticipated, which would suggest that the extent of fermentation of washout fractions in the rumen is incomplete. The maximum gas and VFA production from the soluble fraction was always lower than that of the insoluble washout, and the non-washout fraction. The combination of pressure toasting and pelleting reduced fermentability both in terms of gas and VFA production compared with the other treatments.
An in vitro batch culture method to assess potential fermentability of feed ingredients for monogastric diets
Williams, B.A. ; Bosch, M.W. ; Boer, H. ; Verstegen, M.W.A. ; Tamminga, S. - \ 2005
Animal Feed Science and Technology 123-124 (2005)1. - ISSN 0377-8401 - p. 445 - 462.
chain fatty-acid - gas-production - rumen fluid - fermentation kinetics - detergent fiber - ruminant feeds - prebiotics - excretion - substrate - bacteria
Interest in fermentation within the monogastric digestive tract is growing, particularly relative to animal health. This is of particular importance in relation to the forthcoming European ban on inclusion of anti-microbial growth promotors in animal diets. Fermentable carbohydrates are recognized as having an important role in fermentation in the monogastric digestive tract, and are often added to diets without having been examined for their actual fermentability, particularly in relation to the target animal. We describe an in vitro method to assess feed ingredients, as potential components of monogastric diets, which stimulate a positive fermentation (i.e., ones which will be well fermented and produce more short-chain fatty acids (SCFA) and less ammonia). This technique requires use of a batch culture containing the test substrate and an inoculum of appropriate origin. During fermentation, cumulative gas production is measured at regular intervals, as an indicator of kinetics of the reaction. When fermentation is complete, organic matter losses and end-products such as SCFA and ammonia, are measured. This paper illustrates use of the technique with 45 carbohydrate-based ingredients using faeces from unweaned piglets as inoculum. By assessing potential fermentability of a large number of ingredients, it is possible to make an informed choice as to which substrates are most suited for inclusion in a diet. By combining results with information about transit time, diets can be designed which should stimulate desirable fermentation along the entire digestive tract. In vitro fermentability is a potentially valuable characteristic in diet design, in order to stimulate microbial activity in the digestive tract.
Assessment of the nutritive value of cereal and legume straws based on chemical composition and in vitro digestibility
Lopez, S. ; Davies, D. ; Dhanoa, M.S. ; Dijkstra, J. ; France, J. - \ 2005
Journal of the Science of Food and Agriculture 85 (2005)9. - ISSN 0022-5142 - p. 1550 - 1557.
rumen degradation - gas-production - sacco degradability - ruminant feeds - barley straw - wheat-straw - rice straw - varieties - sheep - fractions
The nutritive value of 17 straws was determined on the basis of their chemical composition, in vitro dry matter (DM) digestibility and rumen fermentation kinetics (from gas production curves measured in vitro). Five roughages were from the cereal species Avena sativa (oat), Hordeum vulgare (barley), Secale cereale (rye), Triticum aestivum (wheat) and Zea mays (maize stover). The other 12 samples were legume straws, two samples from each of the species Cicer arietinum (chickpea), Lens culinaris (lentil) and Phaseolus vulgaris (bean) and one sample from each of the species Lathyrus sativus (chickling vetch), Lupinus albus (white lupin), Pisum sativum (field pea), Vicia articulata (one-flowered vetch), Vicia ervilia (bitter vetch) and Vicia sativa (common vetch). All samples were collected after harvesting from different farms located in León (northwestern Spain). Based on their chemical composition, digestibility and gas production characteristics, species could be clustered into two groups with a significant linkage distance, one for cereal straws that merged at a level of similarity of 80% and the other for legume straws with a degree of similarity of 50%. Species varied widely and significant differences (P <0.05) were observed between the two groups of straws. Legume straws showed higher crude protein (74 ± 6.1 vs 29 ± 2.2 g kg-1 DM) and lower fibre (584 ± 18.1 vs 793 ± 27.5 g neutral detergent fibre kg-1 DM) contents than cereal straws and, consequently, DM digestibility coefficients (0.670 vs 0.609; standard error of difference 0.0054) and metabolisable energy values (7.4 ± 0.15 vs 5.7 ± 0.24 MJ kg-1 DM) were significantly greater in legume than in cereal straws. Although there were noticeable differences among species within each botanical family, legume straws showed better nutritional quality than cereal straws, indicating that they could be considered promising and interesting sources of roughage for incorporation into ruminant diets
Ranking of in vitro fermentability of 20 feedstuffs with an automated gas production technique. Resuls of a ring test
Gelder, A.H. van; Hetta, M. ; Rodrigues, M.A.M. ; Boever, J.L. de; Hartigh, H. Den; Rymer, C. ; Oostrum, M. van; Kaathoven, R. van; Cone, J.W. - \ 2005
Animal Feed Science and Technology 123-124 (2005)pt. 1. - ISSN 0377-8401 - p. 243 - 253.
ruminant feeds - fermentation kinetics - production profiles - fluid
A ring test was completed to determine within laboratory repeatability, and reproducibility among laboratories, of a gas production technique for measuring fermentation kinetics of feeds in rumen fluid. Eight laboratories in different European countries received 20 feed samples. All used the same gas production equipment and method. Gas production profiles were fitted to a multiphasic model and the most important parameters were statistically compared. Although the within laboratory repeatability of, and levels of, calculated parameters differed among laboratories, in most cases there was a high correlation between pairs of laboratories (r = 0.93¿1.00), although in some cases the correlation was only moderate (r = 0.73¿0.87). Within laboratory gas production profiles were influenced by variation in microbiological activity of the rumen fluid and air pressure changes at the end of the run. Among laboratory differences were observed in calibration factors, type of donor animal and diets fed. Variation sources can be minimized using within run standards.
A general compartmental model for interpreting gas production profiles
France, J. ; Lopez, S. ; Kebreab, E. ; Bannink, A. ; Dhanoa, M.S. ; Dijkstra, J. - \ 2005
Animal Feed Science and Technology 123-124 (2005)1. - ISSN 0377-8401 - p. 473 - 485.
observed in-vitro - ruminant feeds - pressure transducer - production kinetics - chemical-analyses - rumen - degradation - fermentation - digestion - extent
Equations to describe gas production profiles, obtained using manual or automated systems for in vitro fermentation of ruminant feeds, are derived from first principles using a general compartmental model. The underlying pools represented are the potentially degradable and undegradable feed fractions, and accumulated gases. Equations derived and investigated mathematically include a Gompertz equation. They were obtained by allowing the fractional rate of degradation to vary with time. The equations permit the extent of ruminal degradation, and hence the supply of microbial protein to the duodenum, to be evaluated thereby linking the gas production technique to animal production.
Technical note: a proposed method to determine the extent of degradation of a feed in the rumen from the degradation profile obtained with the in vitro gas production technique using feces as the inoculum
Dhanoa, M.S. ; France, J. ; Crompton, L.A. ; Mauricio, R.M. ; Kebreab, E. ; Mills, J.A.N. ; Sanderson, R. ; Dijkstra, J. ; Lopez, S. - \ 2004
Journal of Animal Science 82 (2004)3. - ISSN 0021-8812 - p. 733 - 746.
ruminant feeds - apparent digestibility - protein degradability - bovine feces - reproducibility - prediction - kinetics - forages - models - fluid
A method is proposed to determine the extent of degradation in the rumen involving a two-stage mathematical modeling process. In the first stage, a statistical model shifts (or maps) the gas accumulation profile obtained using a fecal inoculum to a ruminal gas profile. Then, a kinetic model determines the extent of degradation in the rumen from the shifted profile. The kinetic model is presented as a generalized mathematical function, allowing any one of a number of alternative equation forms to be selected. This method might allow the gas production technique to become an approach for determining extent of degradation in the rumen, decreasing the need for surgically modified animals while still maintaining the link with the animal. Further research is needed before the proposed methodology can be used as a standard method across a range of feeds
A comparison between buffalo (Bubalus bubalis) and cow (Bos taurus) rumen fluids in terms of the in vitro fermentation characteristics of three fibrous feedstuffs
Calabrò, S. ; Williams, B.A. ; Piccolo, V. ; Infascelli, F. ; Tamminga, S. - \ 2004
Journal of the Science of Food and Agriculture 84 (2004)7. - ISSN 0022-5142 - p. 645 - 652.
gas-production - ruminant feeds - cattle - kinetics - acid
Rumen fluids from fistulated buffalos (Italy-BRF) and cows (Netherlands-CRF) were used as inocula to determine the fermentation kinetics of three forages. These were corn silage (CS), grass silage (GS) and wheat straw (WS) which had originated from both regions, giving six substrates in total. Fermentation kinetics was assessed by the measurement of cumulative gas production. Organic matter (OM) loss and volatile fatty acid (VFA) concentration at the end of the fermentation period were also determined. Both BRF and CRF ranked the substrates in the same order for total VFA, total gas production and the maximum rate of substrate degradation (CS > GS > WS). However, while the ranking of substrates was the same for both species, the absolute values differed significantly between the two inocula. Gas production, expressed as cumulative volume per unit mass of incubated (OMCV, ml g-1) and as cumulative volume per unit mass of OM degraded (OM ml g-1) for CRF was consistently higher than that for BRF for all substrates (p <0.0001). VFA production, particularly of acetic and butyric acids, was significantly (p <0.0001) lower for BRF than for CRF, though the digestibility of OM was the same for both inocula. VFA production predicted by the use of stoichiometric equations was generally higher than the observed gas production. These equations also predicted that the calculated amount of OM utilised for microbial growth was higher for BRF than for CRF. This may explain why diets having the same energy content but less protein can be fed to buffalo since they seem to have a lower requirement for protein compared with cattle. This possibility will need to be investigated in vivo. Given the similar ranking of feedstuffs between the two sources of inocula, these results suggest that either inoculum would be suitable for use in the cumulative gas production test as a measure of feedstuff evaluation. However, given the differences in absolute values, it is recommended that inocula from the species which will receive the feedstuff should be used.
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