Assessing methane emission from dairy cows : modeling and experimental approaches on rumen microbial metabolism
Lingen, Henk J. - \ 2017
Wageningen University. Promotor(en): W.H. Hendriks, co-promotor(en): J. Dijkstra; A. Bannink; C.M. Plugge. - Wageningen : Wageningen University - ISBN 9789463431590 - 207
dairy cows - methane - emission - microbial degradation - rumen metabolism - rumen fermentation - models - fatty acids - biochemical pathways - animal nutrition - nutrition physiology - melkkoeien - methaan - emissie - microbiële afbraak - pensmetabolisme - pensfermentatie - modellen - vetzuren - biochemische omzettingen - diervoeding - voedingsfysiologie
Methane (CH4) is a greenhouse gas (GHG) with a global warming potential of 28 CO2 equivalents. The livestock sector was estimated to emit 7.1 gigatonnes of CO2 equivalents, which is approximately 14.5% of total global anthropogenic GHG emissions. Enteric CH4 production is the main source of GHG emissions from dairy cattle, representing 46% of the global GHG emissions in dairy supply chains. Dairy production has great value in view of the ability of ruminants to effectively turn human inedible biomass into human edible food and to produce food from non-arable land. Consequently, there is an urgent need to develop strategies to decrease dairy cattle enteric CH4 emission. Evaluation of these strategies requires meticulous quantification and increased understanding of anaerobic fermentation and methanogenesis in the rumen ecosystem. The overall aim of this PhD research was, therefore, to quantitatively evaluate enteric CH4 emission from dairy cows as affected by feeding and rumen microbial metabolism.
A meta-analysis was performed to quantify relationships between enteric CH4 yield (per unit of feed and unit of milk) and milk FA profile in dairy cattle and to develop equations to predict CH4 yield based on milk FA profile of cows fed a wide variety of diets. Various milk FA concentrations were significantly or tended to be positively or negatively related to CH4 yield per unit of feed or milk. Mixed model multiple regression resulted in various milk FA included in optimal equations to predict CH4 yield per unit of feed and per unit of milk. These regression equations indicated a moderate potential for using milk FA profile to predict CH4 yield.
For the development of a mechanistic model of CH4 production in the rumen, the thermodynamic control of pH2 on reaction rates of specific fermentation pathways, NADH oxidation and methanogenesis was theoretically explored. This control was determined using the thermodynamic potential factor (FT), which is a dimensionless factor that corrects a predicted kinetic reaction rate for the thermodynamic control exerted. The thermodynamic feasibility of these microbial conversions showed that the control of pH2 on individual VFA produced and associated yield of H2 and CH4 cannot be explained without considering NADH oxidation, with a considerable effect of pH.
For obtaining experimental support of the conclusions drawn from the theoretical exploration, diurnal patterns of gaseous and dissolved metabolite concentrations in the bovine rumen, H2 and CH4 emitted, and the rumen microbiota were monitored. In addition, the effect of dietary inclusion of linseed oil on these patterns was assessed. An in vivo experiment with rumen cannulated dairy cows was performed to study the anaerobic metabolism and the microbiota composition in the rumen. A 100-fold increase in pH2 in the rumen headspace was observed at 0.5 h after feeding, followed by a decline. Qualitatively similar patterns after feeding were observed for H2 and CH4 emission, ethanol and lactate concentrations, and propionate molar proportion, whereas an opposite pattern was seen for acetate molar proportion. Associated with these patterns, a temporal biphasic change in the microbial composition was observed as based on 16S ribosomal RNA with certain taxa specifically associated with each phase. Bacterial concentrations were affected by time and increased by linseed oil supplementation. Archaeal concentrations tended to be affected by time and were not affected by diet, despite linseed oil supplementation tending to decrease the partial pressure and emission of CH4 and tending to increase propionate molar proportion. The various diurnal profiles that were monitored support the key role of the NAD+ to NADH ratio in rumen fermentation and the importance of diurnal dynamics when understanding VFA, H2 and CH4 production.
A dynamic mechanistic model was developed, in which the thermodynamic control of pH2 on VFA fermentation pathways, and methanogenesis in the bovine rumen are incorporated. The model represents substrate degradation, microbial fermentation and methanogenesis in the rumen, with the type of VFA formed to be controlled by the NAD+ to NADH ratio, which in turn is controlled by pH2. Feed composition and feed intake rate representing a twice daily feeding regime were used as model input. The model predicted a marked peak in pH2 after feeding that rapidly declined in time. This peak in pH2 caused a decrease in NAD+ to NADH ratio followed by an increased propionate molar proportion at the expense of acetate molar proportion. In response to feeding, the model predicted a sudden increase and a steady decrease in CH4 production in time. The pattern of CH4 emission rate followed the patterns of pH2 and H2 emission rate, but its magnitude of increase in response to feeding was less pronounced. A global sensitivity analysis indicated the parameter that determines the NADH oxidation rate to explain the most substantial part of the variation of predicted daily CH4 emission. The modeling effort provides the integration of more detailed knowledge than accomplished in previous rumen fermentation models and enables assessment of diurnal dynamics of rumen metabolic pathways yielding VFA, H2 and CH4.
For assessing the general value of the research reported in this thesis, the potential for predicting enteric CH4 emission from dairy cattle based on milk FA profile was discussed in the light of published studies and compared with empirical modeling of enteric CH4 based on feed input. Moreover, the concept of NAD-controlled fermentation was considered in a more general perspective by comparing the rumen ecosystem with bioreactor systems. Furthermore, the feasibility of the developed models as an alternative for IPCC tiered approaches was explored. In conclusion, the research reported in this thesis contributes to an increased understanding of rumen fermentation and microbial metabolism, and has provides a basis to further improve prediction models of enteric CH4 emissions from dairy cattle.
Rumen by-pass copper = Koper voorbij de Pens
Goselink, R.M.A. - \ 2015
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 905) - 22
herkauwers - koper - verteringsabsorptie - pens - pensfermentatie - spijsvertering - voedingsfysiologie - diervoeding - ruminants - copper - digestive absorption - rumen - rumen fermentation - digestion - nutrition physiology - animal nutrition
De absorptie van koper (Cu) bij herkauwers is relatief laag vanwege de interacties tussen Cu en andere bestanddelen van het rantsoen, waardoor onoplosbare complexen gevormd worden die niet worden geabsorbeerd in de dunne darm. Dit kan mogelijk verbeterd worden door pensbestendige Cu bronnen aan te bieden, waardoor de Cu uitscheiding via de mest naar het milieu verminderd kan worden. Het doel van dit project was het evalueren van het effect van pensbestendige Cu bronnen op de Cu absorptie bij herkauwers. Dit is onderzocht met behulp van een in vitro model waarbij verschillende Cu bronnen zijn geïncubeerd om de fermentatie- en verteringsprocessen in het maagdarmkanaal te simuleren. Daarna is een proef uitgevoerd met 18 vleeskalveren waarbij twee pensbestendige Cu bronnen zijn vergeleken met kopersulfaat als controle. Het verschil in Cu absorptie tussen pensbestendige Cu bronnen en kopersulfaat was echter onvoldoende om in deze beperkte proefopzet aangetoond te kunnen worden.
Low emission feed : opportunities to mitigate enteric methane production of dairy cows
Hatew, B. - \ 2015
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Andre Bannink; Wilbert Pellikaan. - Wageningen : Wageningen University - ISBN 9789462574458 - 228
melkkoeien - rundveevoeding - methaanproductie - milieueffect - pensfermentatie - voer - zetmeel - maïskuilvoer - graskuilvoer - diervoeding - dairy cows - cattle feeding - methane production - environmental impact - rumen fermentation - feeds - starch - maize silage - grass silage - animal nutrition
As global demand for high-quality food originating from animal production is expected to rise due to an increasing human population and consumer income level, the expected role of ruminants in meeting this demand brings multiple challenges. Ruminant production needs to adapt to environmental changes and, at the same time, reduce its impact on the environment. Ruminants production systems have a major impact on the environment through the emission of greenhouse gases such as methane (CH4), nitrous oxide and carbon dioxide. Microbial fermentation of feeds in the gastrointestinal tract, known as enteric fermentation, is the main source of CH4 emissions from dairy production. Enteric CH4 emission is strongly related to the amount of feed fermented in the rumen, which depends on feed intake, feed composition and rumen fermentation conditions associated to the intrinsic characteristics of these feeds and the characteristics of the whole diet. Important gaps in knowledge remain however. The prime aim of this thesis was to investigate the effects of various feeding strategies to mitigate enteric CH4 emissions of dairy cows.
First experiment was conducted to investigate the effects of type and level of starch in the concentrate. Inclusion of a high level (53%) of starch in the concentrate that accounted for 40% of the total mixed ration dry matter (DM) produced lower CH4 per unit of estimated rumen fermentable organic matter (eRFOM) than a low level (27% of DM) of starch (43.1 vs. 46.9 g/kg of eRFOM). Methane production per kg of eRFOM also was lower for diets based on rapidly fermentable starch (gelatinized maize grain) compared to diets based on slowly fermentable starch (native maize grain) (42.6 vs. 47.4 g/kg of eRFOM). However, inclusion of 53% of starch in the concentrate from both types of starch did not affect CH4 emission intensity (CH4 Ei) (CH4 emission per kg of fat- and protein-corrected milk; FPCM). In a subsequent experiment, maize silage was prepared from whole-plant maize harvested at a very early (25% DM), early (28% DM), medium (32% DM) and late (40% DM) stage of maturity and fed to dairy cows as an alternative to concentrate as starch source. Diet consisted of (on DM basis) 75% maize silage, 20% concentrate and 5% wheat straw. Increasing harvest maturity of maize silage linearly decreased CH4 yield (21.7, 23.0, 21.0 and 20.1 g/kg of DM intake) and CH4 emission as a fraction of gross energy intake (6.3, 6.7, 6.3 and 6.0%). Methane Ei tended to decrease linearly with maturity (13.0, 13.4, 13.2 and 12.1 g/kg FPCM). In another experiment grass silage as roughage source was tested. This experiment was designed to investigate the effects of N fertilisation of grassland and maturity of grass at cutting on CH4 emission in dairy cows. Two N fertilisation rates (65 vs. 150 kg of N/ha) were examined in combination with three stages of grass maturity (early, 28 days of regrowth; mid, 41 days of regrowth; and late, 62 days of regrowth). Diet contained 80:20 ratio (on DM basis) of grass silage (mainly ryegrass) and concentrate. Dry matter intake decreased with N fertilisation and maturity, and FPCM decreased with maturity but was unaffected by N fertilisation. Methane Ei (mean 15.0 g/kg of FPCM) increased by 31% and CH4 per unit digestible OM intake (mean 33.1 g/kg of DOMI) increased by 15% with increasing maturity. Methane yield (mean 23.5 g/kg of DM intake) and CH4 as a fraction of gross energy intake (mean 7%) increased by 7 and 9% with maturity, respectively, which implies an increased loss of dietary energy with progressing grass maturity. Rate of N fertilisation had no effect on CH4 Ei and CH4 yield.
Despite the importance of in vitro gas production technique for evaluating feeds, in vitro study as a stand-alone approach was considered inadequate to fully evaluate the potential effect of feeds and rumen fermentation modifiers on CH4 production, because in vitro studies are frequently performed separately rather than in parallel with in vivo studies. To test this hypothesis, both in vitro and in vivo CH4 measurements were measured simultaneously using cows in the first experiment that were fed (and adapted to) the same dietary material used as a substrate for in vitro incubation, as donor for microbial inoculum. It was found that 24-h in vitro CH4 (mL/g of incubated organic matter) correlated well with in vivo CH4 when expressed per unit of eRFOM (R2 = 0.54), but not when expressed per unit of organic matter ingested (R2 = 0.04). In the same experiment, results showed that incubation of the same substrate with rumen inocula obtained from donor cows adapted to different diets produced a variable amount of CH4 suggesting that it is important to consider the diet of the donor animal when collecting rumen inocula for in vitro incubation. Even though the in vitro technique has limitations to represent in vivo conditions, it is useful for screening of large sets of animal feeds or feed additives to be used as a CH4 mitigation strategy. In this thesis, two in vitro experiments were conducted to examine the effects of variation in structural composition of condensed tannins (CT) in sainfoin accessions collected from across the world on CH4 production, and CT extracts obtained from a selected sainfoin accessions on CH4 production. Results revealed substantial variation among CT in their effect on in vitro CH4 production and this variation was attributed to differences in chemical structure of CT. Condensed tannins evaluated in this thesis showed to have potential to reduce in vitro CH4 production, but require further investigations to fully evaluate their in vivo effects.
In conclusion, results from the research work conducted in this thesis show that changes in the basal diet of dairy cows and in roughage production management can substantially reduce the amount of enteric CH4 produced and thereby influence the impact of dairy production on the environment.
What happens in the bag? : development and evaluation of a modified in situ protocol to estimate degradation of nitrogen and starch in the rumen
Jonge, L.H. de - \ 2015
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; H. van Laar. - Wageningen : Wageningen University - ISBN 9789462574519 - 175
herkauwers - pensfermentatie - stikstof - zetmeelvertering - pensvertering - protocollen - evaluatie - methodologie - schatting - voedingsfysiologie - ruminants - rumen fermentation - nitrogen - starch digestion - rumen digestion - protocols - evaluation - methodology - estimation - nutrition physiology
The most widely used method to estimate the rumen degradation of dietary components in feedstuffs is the in situ or in sacco method. This method is based on rumen incubation of substrate (feed) in nylon or dacron bags followed by rinsing and analysis of the residue. Small pores in the bag allow microbes to enter the bag whilst a variable portion of the feed is retained in the bag. The results are used to estimate the ruminal effective degradation (ED) that is used in several protein evaluation systems. The weaknesses of the in situ method are its low precision, the lack of standardization, and its inaccuracy. The accuracy can be divided in a bias with respect to the in situ method itself, and the difference between the in situ and in vivo degradation. The bias of the in situ method itself is related to several assumptions regarding the size and degradation rate of the washable fraction, secondary particle loss, and microbial contamination. The aim of this thesis was to examine possibilities to reduce this bias by modification of the in situ methodology.
The bias related to the assumptions regarding the washout fraction was successfully reduced by developing and using a modified rinsing method that involves less vigorously shaking conditions and a solvent which mimics the rumen pH and osmolality. This modified rinsing method markedly reduced the soluble (S) fraction of N, especially for legume seeds, and the non-soluble washout (W-S) fraction, especially for starch, compared to the conventional method. Consequently, the estimation of the ED became less dependent on the assumptions regarding the degradation of the S and W-S fraction. In vitro results did not support the assumption of a much faster degradation of the W-S fraction of starch than that of the non-washout fraction of starch. The modified rinsing method also allowed measuring the in situ degradation of products that contain mainly small particles such as wheat yeast concentrates.
The bias related to the breakdown of particles was also successfully reduced by development and application of a combination of the modified rinsing method and an in vitro method that simulates particulate matter loss during incubation. This in vitro method was based on in situ results obtained with an inert marker (i.e., silica gel) which showed that particulate matter loss during incubation was moderate and limited to particles smaller than approximately 40 μm. Correction for these losses decreased the estimated ED of feed ingredients used. This study also showed that the fractional degradation rate of starch in grains was strongly affected by the process of secondary particulate loss when using the conventional method, and applying the modified rinsing method markedly reduced the error due to secondary particulate loss.
In comparison to the conventional method, the modified method resulted in an increase of the bias related to microbial contamination of the residues. The ratio between diaminopimelic acid (DAPA), a marker for bacterial protein, and N in the residues was higher when using the modified method than that in the conventional method. The results obtained for the modified method also indicated lysis of bacterial cells during rinsing. This bias led to a lower ED when using the modified method with the impact greatly depending on the degree of lysis of bacterial cells.
In summary, the modified method increased the non-washout fraction of N and starch of various feed ingredients, which offers the possibility to use it for a larger range of feed ingredients, and reduced the bias related to assumptions on the washout fraction and the breakdown of particles compared to the conventional method. On the other hand, the modified method increased the bias related to microbial contamination and enlarged the difference between the in situ and in vivo degradation.
Rumen fermentation profile and intestinal digestibility of maize and grass silages
Ali, M. - \ 2013
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): John Cone; Gert van Duinkerken. - S.l. : s.n. - ISBN 9789461736581 - 157
melkkoeien - maïskuilvoer - graskuilvoer - pensfermentatie - verteerbaarheid - darmfysiologie - chemische samenstelling - diervoeding - voedingsfysiologie - dairy cows - maize silage - grass silage - rumen fermentation - digestibility - intestinal physiology - chemical composition - animal nutrition - nutrition physiology
Maize and grass silages are commonly used as major feed materials for dairy cows in Europe and are becoming common parts of dairy cow rations in other parts of the world. Thenutritive value of maize and grass silages varies greatly due to variation in chemical composition. A combination of different factors such as the use of various cultivars, fertilization practices, growing conditions, harvesting technology, maturity at harvest and ensiling conditions cause this variation in chemical composition. The first aim of this thesis was to investigate relationships between the chemical composition and the in situ rumen degradation characteristics and in situ mobile nylon bag digestibility of dietary nutrients of maize and grass silages. Maize and grass silages with a broad range in chemical composition and quality parameters were selected from different Dutch commercial farms. The broad range in the chemical composition of the maize and grass silages resulted in a large variation in rumen degradable fractions of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and starch. The intestinal digestibility of CP, NDF and/or starch was affected by the concentration of these components in the maize and grass silages, by the rumen incubation time and the rumen escape content. Regression equations were developed describing relationships between the chemical composition and the in situ ruminal and postruminal degradation characteristics of dietary nutrients of maize and grass silages. A number of the developed regression equations presented in this thesis can be used for accurate and rapid estimation of the ruminal and postruminal degradation characteristics of dietary nutrients of maize and grass silages, without conducting time consuming and expensive in situ experiments. The second aim of this thesis was to determine whether three cows are sufficient to cover the variation between individual cows in in situ rumen degradation characteristics of dietary nutrients of maize and grass silages. Significant differences (P<0.05) were found between individual cows for a number of parameters of DM, OM and CP of maize silages, indicating that four or more cows should be used for nylon bag incubations of maize silages. For grass silages, no significant differences (P>0.05) between individual cows were found for all the parameters of DM, OM, CP and NDF. The results suggest that using three cows are sufficient for nylon bag incubations of grass silages and pooling of rumen incubated residues is allowed to obtain a representative sample. The third aim of this thesis was to compare two fractionation methods; the washing machine method and a modified method, for nitrogen (N) and starch fractions of maize silages and N fractions of grass silages. The N and/or starch fractions of maize and grass silages determined, using the washing machine method (washing with water for 40 min) and the modified method (shaking with buffer solution for 60 min) were compared. The different methodological approaches of both methods resulted in different values for the washout (W), the soluble (S) and the non-washout (D+U) fractions of N of maize and grass silages and for the W, the insoluble washout (W-S) and the D+U fractions of starch of maize silages. The loss of insoluble small particles of starch was less during shaking of nylon bags in buffer solution, compared to washing nylon bags in the washing machine. Therefore, large differences were found between the D+U fractions of starch determined by both methods compared to the D+U fractions of N of maize silages. The developed regression equations for W, S and D+U fractions of N in grass silages and for D+U fractions of starch in maize silages determined by both methods can be used for rapid estimation of these fractions from chemical characteristics of maize and grass silages. The information on nutrient bioavailability of maize and grass silages presented in this thesis can be used to more accurately formulate dairy ration in terms of maintenance, health and production of dairy cows.
Een vat vol organismen
Vuuren, A.M. van - \ 2010
Veeteelt 27 (2010)11. - ISSN 0168-7565 - p. 48 - 49.
melkveehouderij - melkkoeien - fermentatie - pensvertering - pensfermentatie - voedingsstoornissen - dairy farming - dairy cows - fermentation - rumen digestion - rumen fermentation - nutritional disorders
Een laag melkvetgehalte, dunne mest, een lage voeropname en klauwproblemen bij melkvee worden te gemakkelijk toegeschreven aan stoornissen in de pens. Ook het advies om dan ‘prik’ bij te voeren is een te eenvoudige voorstelling van zaken bij het ontstaan van fermentatiestoornissen.
Rumen-protected rice bran to induce the adaptation of calcium metabolism in dairy cows
Martín-Tereso López, J. - \ 2010
Wageningen University. Promotor(en): Martin Verstegen; Leonard den Hartog, co-promotor(en): H. van Laar. - [S.l. : S.n. - ISBN 9789085856085 - 182
melkkoeien - rijstzemelen - calcium - pensmetabolisme - pensfermentatie - melkziekte - voer - rundveevoeding - diervoeding - voedingsfysiologie - adaptatiefysiologie - dierziektepreventie - dairy cows - rice bran - calcium - rumen metabolism - rumen fermentation - parturient paresis - feeds - cattle feeding - animal nutrition - nutrition physiology - adaptation physiology - animal disease prevention
Dairy cows suffer from hypocalcaemia in the days around calving, which may result in a condition generally known as milk fever. Calcium metabolism sharply shifts at the start of lactation, because Ca needs suddenly become much greater than at the end of gestation. Calcium metabolism is able to adapt to different physiological situations, but adaptation requires several days to be effective, resulting in this transient hypocalcaemia. A way to prevent milk fever is to induce adaptation of Ca metabolism weeks before calving by reducing dietary availability of Ca, to prepare Ca metabolism for calving. Rice bran contains a very low level of Ca and a high level of phytic acid, which is a well-know dietary antagonist of Ca in monogastric species. Preventing the ruminal degradation of phytic acid, rice bran can reduce the nutritional availability of dietary Ca in cows. In this thesis, fat coating and formaldehyde treatment proved effective to protect phytic acid in rice bran from ruminal degradation. Formaldehyde treatment was chosen as the preferred method, because it had no detrimental effects on voluntary feed intake. Feeding rumen-protected rice bran reduced dietary Ca availability, thereby inducing the adaptation of Ca metabolism. Furthermore, the product, fed before calving to multiparous cows, improved calcaemia for the first three days after calving. Rumen-protected rice bran, fed in the last weeks of gestation, could represent a practical dietary strategy to prevent milk fever.
Toevoeging van enkele onderdelen aan een dynamisch pensmodel
Bannink, A. ; Dijkstra, J. - \ 2009
Lelystad : Animal Sciences Group, Wageningen UR (Rapport / Animal Sciences Group 219) - 52
melkveehouderij - melkkoeien - pens - pensfermentatie - pensvertering - vetzuren - modellen - melksamenstelling - dairy farming - dairy cows - rumen - rumen fermentation - rumen digestion - fatty acids - models - milk composition
Het pensmodel van Dijkstra et al. (1992) werd op 3 onderdelen aangepast: een weergave werd toegevoegd voor 1. de invloed van het voeropnamepatroon en van de verkleining en passage van deeltjes op pensfermentatie bij melkkoeien; 2. de invloed van langketen vetzuren op het verloop van de pensfermentatie en omgekeerd, en 3. de vertering in de darm, de absorptie van afzonderlijke typen nutriënten uit het maagdarmkanaal, de benutting van deze nutriënten voor melkproductie en de potentiële melkproductie op deze nutriënten gegeven de melksamenstelling. De toegevoegde onderdelen en het volledige model werden geëvalueerd door een vergelijking tussen modelsimulaties en in de literatuur gerapporteerde effecten en inzichten in het functioneren van de pens. Daarnaast werden modelvoorspellingen vergeleken met gerapporteerde resultaten op enkele praktijkbedrijven
Penssynchronisatie: toetsing in voerderproeven = Synchronization of rumen fermentation: testing in feeding experiments
Duinkerken, G. van; Bakker, J. ; Blok, M.C. ; Brandsma, G.G. ; Crone, J.W. ; Klop, A. ; Remmelink, G.J. ; Vuuren, A.M. van; Zom, R.L.G. - \ 2008
Wageningen : Animal Sciences Group (Rapport / Animal Sciences Group 30) - 75
diervoedering - melkvee - rundveevoeding - proeven - voeropname - stikstof - pens - pensfermentatie - melkproductie - melkeiwit - animal feeding - dairy cattle - cattle feeding - trials - feed intake - nitrogen - rumen - rumen fermentation - milk production - milk protein
Een penssynchronisatiesysteem heeft als doel energie en stikstof gelijktijdig en in de juiste verhouding beschikbaar te laten komen voor de micro-organismen in de pens. Penssynchronisatie blijkt in vivo minder belangrijk dan theoretisch wordt aangenomen. Met het verschijnen van dit rapport en de overige publicaties uit het project “Penssynchronisatie”, hopen de betrokken organisaties een bijdrage te leveren aan een efficiëntere nutriëntenbenutting op Nederlandse melkveebedrijven, met name een efficiënt gebruik van stikstof
Modelling volatile fatty acid dynamics and rumen function in lactating cows
Bannink, A. - \ 2007
Wageningen University. Promotor(en): Seerp Tamminga; J. France, co-promotor(en): Jan Dijkstra. - [S.l.] : S.n. - ISBN 9789085047858 - 251
koeien - lactatie - vluchtige vetzuren - dynamische modellen - pensfermentatie - absorptie - pensepitheel - voedingsfysiologie - celmetabolisme - cows - lactation - volatile fatty acids - dynamic models - rumen fermentation - absorption - rumen epithelium - nutrition physiology - cell metabolism
Mathematical models are developed to quantity and integrate the various processes involved with rumen fermentation. Three extant mechanistic models of rumen fermentation were studied (Baldwin et al., Danfær and Dijkstra et al.), each with a truly dynamic representation but different conceptual approach. The models were compared on mathematical representation of individual processes and their prediction accuracy was evaluated. Although the models predicted similar rates of substrate degradation and rumen outflow of organic matter, total crude protein and microbial protein, they differed substantially in representation of the underlying microbial mechanisms. The model of Baldwin et al. performed best in prediction of the combination of rumen pool sizes and duodenal flows, whereas the model of Dijkstra et al. was evaluated to deliver the most realistic outflow of rapidly fermentable carbohydrates. Further, it was identified that all models needed improvement with respect to the prediction of amounts and type of volatile fatty acids (VFA) produced. In a subsequent evaluation is was investigated to what extent individual model elements, of a selection of five, could be responsible for inaccurate VFA predictions. The results suggested that inaccuracy of stoichiometric coefficients of VFA yield from fermented substrate (VFA coefficients) and incorrect representations of VFA absorption kinetics are the most likely causes. New values of VFA coefficients were derived by regression of a stoichiometric model of VFA yield against data of VFA molar proportions observed in vivo in rumen fluid of lactating cows. Inputs to the model were observed rates of rumen substrate degradation. Regression against simulated data sets including random error indicated that the accuracy of this method to estimate VFA coefficients is acceptable. Estimates from regressions against in vivo data delivered new sets of VFA coefficients for roughage-rich and concentrate-rich diets. In a follow-up study the representation of stoichiometry was made pH-dependent. With regression of this model against in vivo data a profound effect of rumen pH on the type of VFA formed from rapidly fermentable carbohydrates was established. Besides VFA production, the rumen concentrations and the amount and profile of VFA available for the cow are also affected by absorption and metabolism of VFA by epithelial tissues in the rumen wall. A mechanistic model was constructed that represents the dynamics of these processes, including the effects of changes in VFA concentration differences between different compartments, the effect of competitive inhibition between VFA and the effect of changes in surface area and epithelial mass. Although some essential characteristics of VFA transport and intra-epithelial metabolism could be reproduced by the model, it was concluded that there is a definite need for more experimental data. It is concluded that various levels of functioning need to be included when representing whole rumen function. Besides intrinsic degadation characteristics and passage of ingested substrates, environmental conditions in the rumen and the functionality of the rumen wall need to addressed.
Fractions of ruminant feeds: kinetics of degradation in vitro
Azarfar, A. - \ 2007
Wageningen University. Promotor(en): Seerp Tamminga, co-promotor(en): Thomas van der Poel; H. Boer. - [S.l.] : S.n. - ISBN 9789085045571 - 219
herkauwers - voer - concentraten - ingrediënten - fractionering - kinetica - degradatie - fermentatieproducten - pensfermentatie - in vitro - voedingsfysiologie - biochemie - ruminants - feeds - concentrates - ingredients - fractionation - kinetics - degradation - fermentation products - rumen fermentation - in vitro - nutrition physiology - biochemistry
A widely adopted procedure to characterise the degradation in the rumen and its dynamics is the in situ incubation technique that assumes the washable fraction of feeds (W) to be equal to the soluble (S) fraction and that both are rapidly and completely degraded which may not be the case. Because W fraction is washed out of nylon bags, their behaviour cannot directly be measured. This thesis, therefore, aimed to characterise the degradative behaviour of some important unprocessed and processed concentrate (barley, maize, milo, peas, lupins and faba beans) ingredients and their fractions, using a methodology that fractionates feed samples into its inherent constituents (non-washable, NWF; insoluble washable, ISWF and soluble washable fraction, SWF) in combination with an in vitro gas production technique. The results show that the size of the W fraction obtained in nylon bag studies differs from that of the soluble fraction. Except in lupins, ISWF of the concentrate ingredients was very rich in starch. SWF was relatively rich in ash, crude protein, soluble sugars, anda residualfraction(chemically not determined)but contained only a negligible quantity of starch. The degradative behaviour of this difference (ISWF), measured with in vitro gas production,isvery similar to that of the non-washable fraction. The nature of the VFA profile resulting from the fermentation of the different fractions differs between fractions and changes with time of fermentation. Except in lupins, expander processing decreases the contribution of the truly soluble fraction (SWF) in concentrate ingredients. In maize, milo, peas and faba beans, gelatinised starch serves as a binding agent reducing the size of ISWF. However, the pelleting after expander processing disturbs the binding effect of gelatinised starch to some extent, and increases the size of ISWF. In all cereal grains, faba beans and lupins, thermo-mechanical processing (expander processing and ensuing pelleting) shows a tendency to increase the fractional rate of substrate degradation and rate of gas production at the early stage of fermentation, thereby shifting the pattern of fermentation towards a more glucogenic fermentation. Moreover, it appears that the expander processing and the ensuing pelleting process provides a certain level of protection to dietary protein as represented by a lowered NH 3 -N production. Our data show that grinding the samples of technological processing changes the particle size distribution in the samples of processed material. As a consequence, the kinetics of gas productionchange. When monitoring the effects of feed processing by using an in vitro gas production technique, no grinding prior to in vitro incubation should be applied.
Controle over de uitlaatgassen van de koe : Eén koe van Ad en Ine Schepens stoot net zoveel broeikasgas uit als een auto in 40 kilometer
Booij, A. - \ 2006
Nieuwsbrief Koeien & Kansen 2006 (2006)22. - p. 3 - 3.
melkveehouderij - dierlijke meststoffen - methaanproductie - broeikasgassen - pensfermentatie - mineralenboekhouding - dairy farming - animal manures - methane production - greenhouse gases - rumen fermentation - nutrient accounting system
Met het aanpakken van het broeikaseffect wordt er ook naar de melkveehouderij gekeken. Maar hoeveel broeikasgas oftewel methaan komt er eigenlijk uit een koe? En hoe gemakkelijk is het om hieraan te sturen? De koeien van de familie Schepens uit Maarheeze ondergingen de theoretische test. ‘Onbewust doen we al veel om de broeikasgassen te beperken.’
Rumen development in veal (preruminant) calves
Suárez, B.J. - \ 2006
Wageningen University. Promotor(en): Seerp Tamminga, co-promotor(en): Walter Gerrits; Jan Dijkstra. - [S.l.] : S.n. - ISBN 9789085045366 - 174
vleeskalveren - pensontwikkeling - pensfermentatie - concentraten - ruwvoer (roughage) - voer - samenstelling - koolhydraten - enzymactiviteit - mestresultaten - kalvervoeding - veal calves - rumen development - rumen fermentation - concentrates - roughage - feeds - composition - carbohydrates - enzyme activity - fattening performance - calf feeding
Historically, veal calves were fed until slaughter weight with only milk replacer and, in absence of solid feed the physiological development of the forestomachs was limited. In 1997, a new EU legislation stipulated that a minimum amount of solid feed (fiber) has to be provided for the welfare of the calves (solid feed supply reduce abnormal oral behaviors in veal calves; Van Putten, 1982; Veissier et al., 1998); however, no specifications were made about the type and source of feed.Rumen development is triggered by the production of VFA resulting from fermentation of
Uit de mest- en mineralenprogramma's : Een dynamisch model voor het voorspellen van vertering, benutting en uitscheiding bij melkkoeien
Bannink, A. ; Dijkstra, J. - \ 2003
Lelystad : Animal Sciences Group (Informatieblad / Animal Sciences Group 398.40) - 2
pensfermentatie - voederconversie - fosfaat - stikstof - milieuwetgeving - voedingsstoffengehalte - melkveehouderij - voedingswaarde - Nederland - rumen fermentation - feed conversion - phosphate - nitrogen - environmental legislation - nutrient content - dairy farming - nutritive value - Netherlands
Op dit moment wordt in de praktijk van de melkveehouderij uitgegaan van een constante voedingswaarde van een voedermiddel. Bovendien worden in de huidige onderzoekspraktijk erg grove relaties gehanteerd voor de relatie tussen N en P opname en de N en P excretie met urine en feces. Voor een specifieke bedrijfssituatie is echter een veel nauwkeurigere kwantificering mogelijk indien meer rekening gehouden zou worden met de gebeurtenissen die plaats vinden in het maagdarmkanaal en de benutting van individuele nutriënten door de koe. Momenteel wordt binnen programma 398-I een nieuw systeem ontwikkeld dat in staat is om rekening te houden met de gevolgen van een volledig rantsoen (i.t.t. een voederwaarde voor ieder afzonderlijk voedermiddel) en van de omstandigheden in de melkkoe. Hiermee is nauwkeuriger de invloed vast te stellen van een gewijzigde voederstrategie op de N en P benutting en op de hoeveelheid en aard van de excretie van N en P met urine en feces. Reeds 10 jaar is een realistisch model voor pensfermentatie beschikbaar (Dijkstra et al., 1992). Het model wordt nu aangepast en verfijnd zodat de complexiteit van het model een praktijktoepassing niet meer in de weg zal staan
Mathematical modelling and integration of rumen fermentation processes
Dijkstra, J. - \ 1993
Agricultural University. Promotor(en): S. Tamminga. - S.l. : Dijkstra - ISBN 9789054850885 - 221
herkauwers - pensfermentatie - pensvertering - wiskundige modellen - diervoeding - voedingsfysiologie - ruminants - rumen fermentation - rumen digestion - mathematical models - animal nutrition - nutrition physiology - cum laude
In ruminants, the profile of nutrients available for absorption generally differs considerably from that ingested. These differences result from the metabolic activities of the rumen microorganisms. The main aim of the present study, was to model the rumen fermentation processes, to achieve the integration and quantification of these processes, and with the long term aim of improving the level and efficiency of animal performance with respect to desired products and waste. The dynamic, mechanistic models developed in this study addressed specific aspects of rumen function which were not included in previous models, but have been recognized as being of major importance in the transformation of ingested to absorbed nutrients. In particular, the representation of microbial metabolism has been improved. Results of model evaluation showed that the outflow of nutrients from the rumen (NDF, starch, soluble sugars, nitrogen) was predicted well on a wide range of dietary inputs. However, the type of VFA was not predicted satisfactorily. Therefore, an experiment was conducted to study absorption rates of VFA from the rumen. It was found that VFA absorption is affected to a different extent by rumen volume, pH and VFA concentration. These factors should be taken into account if production of individual VFA in the rumen is to be predicted accurately. In another model developed in the present study, major aspects of rumen protozoal metabolism have been represented mathematically. The mathematical integration of protozoal, bacterial and dietary characteristics provided a quantitative understanding of mechanisms of protozoal responses and their effects on nutrients available for absorption to changes in dietary inputs. The prediction of responses of the amount of product (milk, meat, wool) and the product composition should recognize metabolism of individual substrates within the rumen or available after absorption. The models developed in this study provide a basis for the estimation of the profile of nutrients available for absorption, but further consideration of the prediction of type of VFA formed in the rumen should have a high priority.