Staff Publications

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.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Evaluation of the performance of existing mathematical models predicting enteric methane emissions from ruminants: Animal categories and dietary mitigation strategies
Benaouda, Mohammed ; Martin, Cécile ; Li, Xinran ; Kebreab, Ermias ; Hristov, Alexander N. ; Yu, Zhongtang ; Yáñez-Ruiz, David R. ; Reynolds, Christopher K. ; Crompton, L.A. ; Dijkstra, Jan ; Bannink, André ; Schwarm, Angela ; Kreuzer, Michael ; McGee, Mark ; Lund, P. ; Hellwing, Anne L.F. ; Weisbjerg, Martin R. ; Moate, Peter J. ; Bayat, A.R. ; Shingfield, Kevin J. ; Peiren, Nico ; Eugène, M. - \ 2019
Animal Feed Science and Technology 255 (2019). - ISSN 0377-8401
Dietary strategy - Methane emission - Model evaluation - Ruminant

The objective of this study was to evaluate the performance of existing models predicting enteric methane (CH4) emissions, using a large database (3183 individual data from 103 in vivo studies on dairy and beef cattle, sheep and goats fed diets from different countries). The impacts of dietary strategies to reduce CH4 emissions, and of diet quality (described by organic matter digestibility (dOM) and neutral-detergent fiber digestibility (dNDF)) on model performance were assessed by animal category. The models were first assessed based on the root mean square prediction error (RMSPE) to standard deviation of observed values ratio (RSR) to account for differences in data between models and then on the RMSPE. For dairy cattle, the CH4 (g/d) predicting model based on feeding level (dry matter intake (DMI)/body weight (BW)), energy digestibility (dGE) and ether extract (EE) had the smallest RSR (0.66) for all diets, as well as for the high-EE diets (RSR = 0.73). For mitigation strategies based on lowering NDF or improving dOM, the same model (RSR = 0.48 to 0.60) and the model using DMI and neutral- and acid-detergent fiber intakes (RSR = 0.53) had the smallest RSR, respectively. For diets with high starch (STA), the model based on nitrogen, ADF and STA intake presented the smallest RSR (0.84). For beef cattle, all evaluated models performed moderately compared with the models of dairy cattle. The smallest RSR (0.83) was obtained using variables of energy intake, BW, forage content and dietary fat, and also for the high-EE and the low-NDF diets (RSR = 0.84 to 0.86). The IPCC Tier 2 models performed better when dietary STA, dOM or dNDF were high. For sheep and goats, the smallest RSR was observed from a model for sheep based on dGE intake (RSR = 0.61). Both IPCC models had low predictive ability when dietary EE, NDF, dOM and dNDF varied (RSR = 0.57 to 1.31 in dairy, and 0.65 to 1.24 in beef cattle). The performance of models depends mostly on explanatory variables and not on the type of data (individual vs. treatment means) used in their development or evaluation. Some empirical models give satisfactory prediction error compared with the error associated with measurement methods. For better prediction, models should include feed intake, digestibility and additional information on dietary concentrations of EE and structural and nonstructural carbohydrates to account for different dietary mitigating strategies.

Prediction of enteric methane production, yield and intensity of beef cattle using an intercontinental database
Lingen, Henk J. van; Niu, Mutian ; Kebreab, Ermias ; Valadares Filho, Sebastião C. ; Rooke, John A. ; Duthie, Carol Anne ; Schwarm, Angela ; Kreuzer, Michael ; Hynd, Phil I. ; Caetano, Mariana ; Eugène, Maguy ; Martin, Cécile ; McGee, Mark ; O'Kiely, Padraig ; Hünerberg, Martin ; McAllister, Tim A. ; Berchielli, Telma T. ; Messana, Juliana D. ; Peiren, Nico ; Chaves, Alex V. ; Charmley, Ed ; Cole, N.A. ; Hales, Kristin E. ; Lee, Sang Suk ; Berndt, Alexandre ; Reynolds, Christopher K. ; Crompton, Les A. ; Bayat, Ali R. ; Yáñez-Ruiz, David R. ; Yu, Zhongtang ; Bannink, André ; Dijkstra, Jan ; Casper, David P. ; Hristov, Alexander N. - \ 2019
Agriculture, Ecosystems and Environment 283 (2019). - ISSN 0167-8809
Dietary variables - Empirical modeling - Forage content - Geographical region - Methane emission

Enteric methane (CH4) production attributable to beef cattle contributes to global greenhouse gas emissions. Reliably estimating this contribution requires extensive CH4 emission data from beef cattle under different management conditions worldwide. The objectives were to: 1) predict CH4 production (g d−1 animal−1), yield [g (kg dry matter intake; DMI)−1] and intensity [g (kg average daily gain)−1] using an intercontinental database (data from Europe, North America, Brazil, Australia and South Korea); 2) assess the impact of geographic region, and of higher- and lower-forage diets. Linear models were developed by incrementally adding covariates. A K-fold cross-validation indicated that a CH4 production equation using only DMI that was fitted to all available data had a root mean square prediction error (RMSPE; % of observed mean) of 31.2%. Subsets containing data with ≥25% and ≤18% dietary forage contents had an RMSPE of 30.8 and 34.2%, with the all-data CH4 production equation, whereas these errors decreased to 29.3 and 28.4%, respectively, when using CH4 prediction equations fitted to these subsets. The RMSPE of the ≥25% forage subset further decreased to 24.7% when using multiple regression. Europe- and North America-specific subsets predicted by the best performing ≥25% forage multiple regression equation had RMSPE of 24.5 and 20.4%, whereas these errors were 24.5 and 20.0% with region-specific equations, respectively. The developed equations had less RMSPE than extant equations evaluated for all data (22.5 vs. 23.2%), for higher-forage (21.2 vs. 23.1%), but not for the lower-forage subsets (28.4 vs. 27.9%). Splitting the dataset by forage content did not improve CH4 yield or intensity predictions. Predicting beef cattle CH4 production using energy conversion factors, as applied by the Intergovernmental Panel on Climate Change, indicated that adequate forage content-based and region-specific energy conversion factors improve prediction accuracy and are preferred in national or global inventories.

Invited review: Nitrogen in ruminant nutrition: A review of measurement techniques
Hristov, A.N. ; Bannink, A. ; Crompton, L.A. ; Huhtanen, P. ; Kreuzer, M. ; McGee, M. ; Nozière, P. ; Reynolds, C.K. ; Bayat, A.R. ; Yáñez-Ruiz, D.R. ; Dijkstra, J. ; Kebreab, E. ; Schwarm, A. ; Shingfield, K.J. ; Yu, Z. - \ 2019
Journal of Dairy Science 102 (2019)7. - ISSN 0022-0302 - p. 5811 - 5852.
environment - manure - metabolism - nitrogen - ruminant animal - technique

Nitrogen is a component of essential nutrients critical for the productivity of ruminants. If excreted in excess, N is also an important environmental pollutant contributing to acid deposition, eutrophication, human respiratory problems, and climate change. The complex microbial metabolic activity in the rumen and the effect on subsequent processes in the intestines and body tissues make the study of N metabolism in ruminants challenging compared with nonruminants. Therefore, using accurate and precise measurement techniques is imperative for obtaining reliable experimental results on N utilization by ruminants and evaluating the environmental impacts of N emission mitigation techniques. Changeover design experiments are as suitable as continuous ones for studying protein metabolism in ruminant animals, except when changes in body weight or carryover effects due to treatment are expected. Adaptation following a dietary change should be allowed for at least 2 (preferably 3) wk, and extended adaptation periods may be required if body pools can temporarily supply the nutrients studied. Dietary protein degradability in the rumen and intestines are feed characteristics determining the primary AA available to the host animal. They can be estimated using in situ, in vitro, or in vivo techniques with each having inherent advantages and disadvantages. Accurate, precise, and inexpensive laboratory assays for feed protein availability are still needed. Techniques used for direct determination of rumen microbial protein synthesis are laborious and expensive, and data variability can be unacceptably large; indirect approaches have not shown the level of accuracy required for widespread adoption. Techniques for studying postruminal digestion and absorption of nitrogenous compounds, urea recycling, and mammary AA metabolism are also laborious, expensive (especially the methods that use isotopes), and results can be variable, especially the methods based on measurements of digesta or blood flow. Volatile loss of N from feces and particularly urine can be substantial during collection, processing, and analysis of excreta, compromising the accuracy of measurements of total-tract N digestion and body N balance. In studying ruminant N metabolism, nutritionists should consider the longer term fate of manure N as well. Various techniques used to determine the effects of animal nutrition on total N, ammonia- or nitrous oxide-emitting potentials, as well as plant fertilizer value, of manure are available. Overall, methods to study ruminant N metabolism have been developed over 150 yr of animal nutrition research, but many of them are laborious and impractical for application on a large number of animals. The increasing environmental concerns associated with livestock production systems necessitate more accurate and reliable methods to determine manure N emissions in the context of feed composition and ruminant N metabolism.

The value of manure - Manure as co-product in life cycle assessment
Leip, Adrian ; Ledgard, Stewart ; Uwizeye, Aimable ; Palhares, Julio C.P. ; Aller, M.F. ; Amon, Barbara ; Binder, Michael ; Cordovil, Claudia M.D.S. ; Camillis, Camillo De; Dong, Hongming ; Fusi, Alessandra ; Helin, Janne ; Hörtenhuber, Stefan ; Hristov, Alexander N. ; Koelsch, Richard ; Liu, Chunjiang ; Masso, Cargele ; Nkongolo, Nsalambi V. ; Patra, Amlan K. ; Redding, Matthew R. ; Rufino, Mariana C. ; Sakrabani, Ruben ; Thoma, Greg ; Vertès, Françoise ; Wang, Ying - \ 2019
Journal of Environmental Management 241 (2019). - ISSN 0301-4797 - p. 293 - 304.
Livestock production is important for food security, nutrition, and landscape maintenance, but it is associated with several environmental impacts. To assess the risk and benefits arising from livestock production, transparent and robust indicators are required, such as those offered by life cycle assessment. A central question in such approaches is how environmental burden is allocated to livestock products and to manure that is re-used for agricultural production. To incentivize sustainable use of manure, it should be considered as a co-product as long as it is not disposed of, or wasted, or applied in excess of crop nutrient needs, in which case it should be treated as a waste. This paper proposes a theoretical approach to define nutrient requirements based on nutrient response curves to economic and physical optima and a pragmatic approach based on crop nutrient yield adjusted for nutrient losses to atmosphere and water. Allocation of environmental burden to manure and other livestock products is then based on the nutrient value from manure for crop production using the price of fertilizer nutrients. We illustrate and discuss the proposed method with two case studies.
Methodologies for Assessing Disease Tolerance in Pigs
Nakov, Dimitar ; Hristov, Slavcha ; Stankovic, Branislav ; Pol, Françoise ; Ivan Dimitrov, Ivan ; Dixhoorn, I.D.E. van - \ 2019
behavior - disease tolerance - environment - performance - stress
Features of intensive farming can seriously threaten pig homeostasis, well-being and productivity. Disease tolerance of an organism is the adaptive ability in preserving homeostasis and at the same time limiting the detrimental impact that infection can inflict on its health and performance without affecting pathogen burden per se. While disease resistance (DRs) can be assessed measuring appropriately the pathogen burden within the host, the tolerance cannot be quantified easily. Indeed, it requires the assessment of the changes in performance as well as the changes in pathogen burden. In this paper, special attention is given to criteria required to standardize methodologies for assessing disease tolerance (DT) in respect of infectious diseases in pigs. The concept is applied to different areas of expertise and specific examples are given. The basic physiological mechanisms of DT are reviewed. Disease tolerance pathways, genetics of the tolerance-related traits, stress and disease tolerance, and role of metabolic stress in DT are described. In addition, methodologies based on monitoring of growth and reproductive performance, welfare, emotional affective states, sickness behavior for assessment of disease tolerance, and methodologies based on the relationship between environmental challenges and disease tolerance are considered. Automated Precision Livestock Farming technologies available for monitoring performance, health and welfare-related measures in pig farms, and their limitations regarding DT in pigs are also presented. Since defining standardized methodologies for assessing DT is a serious challenge for biologists, animal scientists and veterinarians, this work should contribute to improvement of health, welfare and production in pigs.
Letter to the Editor : A response to Huhtanen and Hristov (2018)
Bovenhuis, Henk ; Engelen, Sabine van; Visker, Marleen H.P.W. - \ 2018
Journal of Dairy Science 101 (2018)11. - ISSN 0022-0302 - p. 9621 - 9622.
Symposium review: Uncertainties in enteric methane inventories, measurement techniques, and prediction models
Hristov, A.N. ; Kebreab, Ermias ; Niu, Mutian ; Oh, J. ; Bannink, A. ; Bayat, Ali R. ; Boland, Tommy ; Brito, A.F. ; Casper, D.P. ; Crompton, Les A. ; Dijkstra, J. ; Eugène, Maguy A. ; Garnsworthy, Phil C. ; Haque, N. ; Hellwing, Anne L.F. ; Huhtanen, Pekka ; Kreuzer, Michael ; Lund, Peter ; Madsen, Jørgen ; Martin, C. ; Moate, P.J. ; Muetzel, Stefan ; Muñoz, Camila ; Peiren, Nico ; Powell, J.M. ; Reynolds, Chris ; Schwarm, Angela ; Shingfield, Kevin J. ; Storlien, Tonje M. ; Weisbjerg, Martin Riis ; Yáñez-Ruiz, D.R. ; Yu, Z. - \ 2018
Journal of Dairy Science 101 (2018)7. - ISSN 0022-0302 - p. 6655 - 6674.
Ruminant production systems are important contributors to anthropogenic methane (CH4) emissions, but there are large uncertainties in national and global livestock CH4 inventories. Sources of uncertainty in enteric CH4 emissions include animal inventories, feed dry matter intake (DMI), ingredient and chemical composition of the diets, and CH4 emission factors. There is also significant uncertainty associated with enteric CH4 measurements. The most widely used techniques are respiration chambers, the sulfur hexafluoride (SF6) tracer technique, and the automated head-chamber system (GreenFeed; C-Lock Inc., Rapid City, SD). All 3 methods have been successfully used in a large number of experiments with dairy or beef cattle in various environmental conditions, although studies that compare techniques have reported inconsistent results. Although different types of models have been developed to predict enteric CH4 emissions, relatively simple empirical (statistical) models have been commonly used for inventory purposes because of their broad applicability and ease of use compared with more detailed empirical and process-based mechanistic models. However, extant empirical models used to predict enteric CH4 emissions suffer from narrow spatial focus, limited observations, and limitations of the statistical technique used. Therefore, prediction models must be developed from robust data sets that can only be generated through collaboration of scientists across the world. To achieve high prediction accuracy, these data sets should encompass a wide range of diets and production systems within regions and globally. Overall, enteric CH4 prediction models are based on various animal or feed characteristic inputs but are dominated by DMI in one form or another. As a result, accurate prediction of DMI is essential for accurate prediction of livestock CH4 emissions. Analysis of a large data set of individual dairy cattle data showed that simplified enteric CH4 prediction models based on DMI alone or DMI and limited feed- or animal-related inputs can predict average CH4 emission with a similar accuracy to more complex empirical models. These simplified models can be reliably used for emission inventory purposes.
Prediction of enteric methane production, yield, and intensity in dairy cattle using an intercontinental database
Niu, Mutian ; Kebreab, Ermias ; Hristov, Alexander N. ; Oh, Joonpyo ; Arndt, Claudia ; Bannink, André ; Bayat, Ali R. ; Brito, André F. ; Boland, Tommy ; Casper, David ; Crompton, Les A. ; Dijkstra, Jan ; Eugène, Maguy A. ; Garnsworthy, Phil C. ; Haque, Md Najmul ; Hellwing, Anne L.F. ; Huhtanen, Pekka ; Kreuzer, Michael ; Kuhla, Bjoern ; Lund, Peter ; Madsen, Jørgen ; Martin, Cécile ; Mcclelland, Shelby C. ; Mcgee, Mark ; Moate, Peter J. ; Muetzel, Stefan ; Muñoz, Camila ; O'Kiely, Padraig ; Peiren, Nico ; Reynolds, Christopher K. ; Schwarm, Angela ; Shingfield, Kevin J. ; Storlien, Tonje M. ; Weisbjerg, Martin R. ; Yáñez-Ruiz, David R. ; Yu, Zhongtang - \ 2018
Global Change Biology 24 (2018)8. - ISSN 1354-1013 - p. 3368 - 3389.
Dairy cows - Dry matter intake - Enteric methane emissions - Methane intensity - Methane yield - Prediction models
Enteric methane (CH4) production from cattle contributes to global greenhouse gas emissions. Measurement of enteric CH4 is complex, expensive, and impractical at large scales; therefore, models are commonly used to predict CH4 production. However, building robust prediction models requires extensive data from animals under different management systems worldwide. The objectives of this study were to (1) collate a global database of enteric CH4 production from individual lactating dairy cattle; (2) determine the availability of key variables for predicting enteric CH4 production (g/day per cow), yield [g/kg dry matter intake (DMI)], and intensity (g/kg energy corrected milk) and their respective relationships; (3) develop intercontinental and regional models and cross-validate their performance; and (4) assess the trade-off between availability of on-farm inputs and CH4 prediction accuracy. The intercontinental database covered Europe (EU), the United States (US), and Australia (AU). A sequential approach was taken by incrementally adding key variables to develop models with increasing complexity. Methane emissions were predicted by fitting linear mixed models. Within model categories, an intercontinental model with the most available independent variables performed best with root mean square prediction error (RMSPE) as a percentage of mean observed value of 16.6%, 14.7%, and 19.8% for intercontinental, EU, and United States regions, respectively. Less complex models requiring only DMI had predictive ability comparable to complex models. Enteric CH4 production, yield, and intensity prediction models developed on an intercontinental basis had similar performance across regions, however, intercepts and slopes were different with implications for prediction. Revised CH4 emission conversion factors for specific regions are required to improve CH4 production estimates in national inventories. In conclusion, information on DMI is required for good prediction, and other factors such as dietary neutral detergent fiber (NDF) concentration, improve the prediction. For enteric CH4 yield and intensity prediction, information on milk yield and composition is required for better estimation.
Enteric methane emissions: Prediction and mitigation, the GLOBAL NETWORK project
Hristov, A.N. ; Kebreab, E. ; Niu, M. ; Oh, J. ; Arndt, C. ; Bannink, A. ; Bayat, A.R. ; Brito, A.F. ; Casper, D. ; Crompton, L.A. ; Dijkstra, J. ; Garnsworthy, P.C. ; Haque, N. ; Hellwing, A.L.F. ; Huhtanen, P. ; Kreuzer, M. ; Kuhla, B. ; Lund, Peter ; Madsen, J. ; McClelland, S.C. ; Moate, P.J. ; Muñoz, Camila ; Peiren, N. ; Powell, J.M. ; Reynolds, Chris ; Schwarm, A. ; Shingfield, K.J. ; Storlien, T.M. ; Weisbjerg, M.R. - \ 2017
Journal of Dairy Science 100 (2017)Supplement 2. - ISSN 0022-0302 - p. 430 - 431.
Database construction for model comparisons of methane emissions by ruminants in relation to feed
Li, X. ; Martin, C. ; Kebreab, E. ; Hristov, A.N. ; Yu, Z. ; McGee, M. ; Yáñez-Ruiz, D.R. ; Shingfield, K.J. ; Bayat, A.R. ; Reynolds, Chris ; Crompton, L.A. ; Dijkstra, J. ; Bannink, A. ; Schwarm, A. ; Kreuzer, M. ; Lund, Peter ; Hellwing, A.L.F. ; Moate, P.J. ; Peiren, N. ; Eugène, M. - \ 2017
In: Book of Abstracts of the 68th Annual Meeting of the European Federation of Animal Science. - Wageningen : Wageningen Academic Publishers (Book of abstracts 23) - ISBN 9789086863129 - p. 201 - 201.
Review of current in vivo measurement techniques for quantifying enteric methane emission from ruminants
Hammond, K.J. ; Crompton, L.A. ; Bannink, A. ; Dijkstra, J. ; Yáñez-Ruiz, D.R. ; O’Kiely, P. ; Kebreab, E. ; Eugène, M.A. ; Yu, Z. ; Shingfield, K.J. ; Schwarm, A. ; Hristov, A.N. ; Reynolds, C.K. - \ 2016
Animal Feed Science and Technology 219 (2016). - ISSN 0377-8401 - p. 13 - 30.
Ruminant husbandry is a major source of anthropogenic greenhouse gases (GHG). Filling knowledge gaps and providing expert recommendation are important for defining future research priorities, improving methodologies and establishing science-based GHG mitigation solutions to government and non-governmental organisations, advisory/extension networks, and the ruminant livestock sector. The objectives of this review is to summarize published literature to provide a detailed assessment of the methodologies currently in use for measuring enteric methane (CH4) emission from individual animals under specific conditions, and give recommendations regarding their application. The methods described include respiration chambers and enclosures, sulphur hexafluoride tracer (SF6) technique, and techniques based on short-term measurements of gas concentrations in samples of exhaled air. This includes automated head chambers (e.g. the GreenFeed system), the use of carbon dioxide (CO2) as a marker, and (handheld) laser CH4 detection. Each of the techniques are compared and assessed on their capability and limitations, followed by methodology recommendations. It is concluded that there is no ‘one size fits all’ method for measuring CH4 emission by individual animals. Ultimately, the decision as to which method to use should be based on the experimental objectives and resources available. However, the need for high throughput methodology e.g. for screening large numbers of animals for genomic studies, does not justify the use of methods that are inaccurate. All CH4 measurement techniques are subject to experimental variation and random errors. Many sources of variation must be considered when measuring CH4 concentration in exhaled air samples without a quantitative or at least regular collection rate, or use of a marker to indicate (or adjust) for the proportion of exhaled CH4 sampled. Consideration of the number and timing of measurements relative to diurnal patterns of CH4 emission and respiratory exchange are important, as well as consideration of feeding patterns and associated patterns of rumen fermentation rate and other aspects of animal behaviour. Regardless of the method chosen, appropriate calibrations and recovery tests are required for both method establishment and routine operation. Successful and correct use of methods requires careful attention to detail, rigour, and routine self-assessment of the quality of the data they provide.
Greenhouse gas mitigation potentials in the livestock sector
Herrero, Mario ; Henderson, Benjamin ; Havlík, Petr ; Thornton, Philip K. ; Conant, Richard T. ; Smith, Pete ; Wirsenius, Stefan ; Hristov, Alexander N. ; Gerber, P.J. ; Gill, Margaret ; Butterbach-bahl, Klaus ; Valin, Hugo ; Garnett, Tara ; Stehfest, Elke - \ 2016
Nature Climate Change 6 (2016)5. - ISSN 1758-678X - p. 452 - 461.
The livestock sector supports about 1.3 billion producers and retailers, and contributes 40–50% of agricultural GDP. We estimated that between 1995 and 2005, the livestock sector was responsible for greenhouse gas emissions of 5.6–7.5 GtCO2e yr–1. Livestock accounts for up to half of the technical mitigation potential of the agriculture, forestry and land-use sectors, through management options that sustainably intensify livestock production, promote carbon sequestration in rangelands and reduce emissions from manures, and through reductions in the demand for livestock products. The economic potential of these management alternatives is less than 10% of what is technically possible because of adoption constraints, costs and numerous trade-offs. The mitigation potential of reductions in livestock product consumption is large, but their economic potential is unknown at present. More research and investment are needed to increase the affordability and adoption of mitigation practices, to moderate consumption of livestock products where appropriate, and to avoid negative impacts on livelihoods, economic activities and the environment
Design, implementation and interpretation of in vitro batch culture experiments to assess enteric methane mitigation in ruminants-a review
Yáñez-Ruiz, D.R. ; Bannink, A. ; Dijkstra, Jan ; Kebreab, E. ; Morgavi, D.P. ; O'Kiely, P. ; Reynolds, C.K. ; Schwarm, A. ; Shingfield, K.J. ; Yu, Z. ; Hristov, A.N. - \ 2016
Animal Feed Science and Technology 216 (2016). - ISSN 0377-8401 - p. 1 - 18.
Feed evaluation - In vitro gas production - Methane - Microbial inoculum - Mitigation - Rumen

In vitro fermentation techniques (IVFT) have been widely used to evaluate the nutritive value of feeds for ruminants and in the last decade to assess the effect of different nutritional strategies on methane (CH4) production. However, many technical factors may influence the results obtained. The present review has been prepared by the 'Global Network' FACCE-JPI international research consortium to provide a critical evaluation of the main factors that need to be considered when designing, conducting and interpreting IVFT experiments that investigate nutritional strategies to mitigate CH4 emission from ruminants. Given the increasing and wide-scale use of IVFT, there is a need to critically review reports in the literature and establish what criteria are essential to the establishment and implementation of in vitro techniques. Key aspects considered include: i) donor animal species and number of animal used, ii) diet fed to donor animals, iii) collection and processing of rumen fluid as inoculum, iv) choice of substrate and incubation buffer, v) incubation procedures and CH4 measurements, vi) headspace gas composition and vii) comparability of in vitro and in vivo measurements. Based on an evaluation of experimental evidence, a set of technical recommendations are presented to harmonize IVFT for feed evaluation, assessment of rumen function and CH4 production.

GLOBAL NETWORK for the development of nutrition-related strategies for mitigation of methane and nitrous oxide emissions from ruminant livestock
Hristov, A.N. ; Kebreab, E. ; Yu, Z.T. ; Martin, C. ; Eugène, M. ; Yáñez-Ruiz, D.R. ; Shingfield, K.J. ; Ahvenjärvi, S. ; O'Kiely, P. ; Reynolds, C.K. ; Hammond, K.J. ; Dijkstra, J. ; Bannink, A. ; Schwarm, A. ; Kreuzer, M. - \ 2014
In: 2014 Joint Annual Meeting Abstract Book. - - p. 860 - 860.
Nutritional and management strategies to mitigate animal greenhouse gas emissions
Hristov, A.N. ; Oh, J. ; Lee, C. ; Meinen, R. ; Montes, F. ; Ott, T. ; Firkins, J.L. ; Rotz, A. ; Dell, C. ; Adesogan, A.T. ; Yang, W.Z. ; Tricarico, J.M. ; Kebreab, E. ; Waghorn, G. ; Dijkstra, J. ; Oosting, S.J. ; Gerber, P.J. ; Henderson, B.L. ; Makkar, H.P.S. - \ 2013
In: Proceedings 2013 24th Annual Florida Ruminant Nutrition Symposium, 5-6 February 2013, Gainesville, Florida, USA. - Gainesville : University of Florida - p. 90 - 98.
Mitigation of methane and nitrous oxide emissions from animal operations: III. A review of animal management mitigation options
Hristov, A.N. ; Ott, T. ; Tricarico, J. ; Rotz, A. ; Waghorn, G. ; Adesogan, A.T. ; Dijkstra, J. ; Montes, F. ; Oh, J. ; Kebreab, E. ; Oosting, S.J. ; Gerber, P.J. ; Henderson, B.L. ; Makkar, H.P.S. ; Firkins, J.L. - \ 2013
Journal of Animal Science 91 (2013)11. - ISSN 0021-8812 - p. 5095 - 5113.
greenhouse-gas emissions - crop-livestock systems - recombinant bovine somatotropin - residual feed-intake - different roughage contents - holstein-friesian cows - dry period management - pastoral dairy farms - 2 complete diets - reproductive-performance
The goal of this review was to analyze published data on animal management practices that mitigate enteric methane (CH4) and nitrous oxide (N2O) emissions from animal operations. Increasing animal productivity can be a very effective strategy for reducing greenhouse gas (GHG) emissions per unit of livestock product. Improving the genetic potential of animals through planned cross-breeding or selection within breeds and achieving this genetic potential through proper nutrition and improvements in reproductive efficiency, animal health, and reproductive lifespan are effective approaches for improving animal productivity and reducing GHG emission intensity. In subsistence production systems, reduction of herd size would increase feed availability and productivity of individual animals and the total herd, thus lowering CH4 emission intensity. In these systems, improving the nutritive value of low-quality feeds for ruminant diets can have a considerable benefit on herd productivity while keeping the herd CH4 output constant or even decreasing it. Residual feed intake may be a tool for screening animals that are low CH4 emitters, but there is currently insufficient evidence that low residual feed intake animals have a lower CH4 yield per unit of feed intake or animal product. Reducing age at slaughter of finished cattle and the number of days that animals are on feed in the feedlot can significantly reduce GHG emissions in beef and other meat animal production systems. Improved animal health and reduced mortality and morbidity are expected to increase herd productivity and reduce GHG emission intensity in all livestock production systems. Pursuing a suite of intensive and extensive reproductive management technologies provides a significant opportunity to reduce GHG emissions. Recommended approaches will differ by region and species but should target increasing conception rates in dairy, beef, and buffalo, increasing fecundity in swine and small ruminants, and reducing embryo wastage in all species. Interactions among individual components of livestock production systems are complex but must be considered when recommending GHG mitigation practices.
Mitigation of methane and nitrous oxide emissions from animal operations: I. A review of enteric methane mitigation options
Hristov, A.N. ; Oh, J. ; Firkins, J. ; Dijkstra, J. ; Kebreab, E. ; Waghorn, G. ; Makkar, H.P.S. ; Adesogan, A.T. ; Yang, W. ; Lee, C. ; Gerber, P.J. ; Henderson, B.L. ; Tricarico, J.M. - \ 2013
Journal of Animal Science 91 (2013)11. - ISSN 0021-8812 - p. 5045 - 5069.
lactating dairy-cows - ryegrass lolium-perenne - fatty-acid-composition - wet distillers grains - total mixed ration - dietary nitrate supplementation - rumen microbial-populations - sulla hedysarum-coronarium - greenhouse-gas emissions - clover trifolium-repens
The goal of this review was to analyze published data related to mitigation of enteric methane (CH4) emissions from ruminant animals to document the most effective and sustainable strategies. Increasing forage digestibility and digestible forage intake was one of the major recommended CH4 mitigation practices. Although responses vary, CH4 emissions can be reduced when corn silage replaces grass silage in the diet. Feeding legume silages could also lower CH4 emissions compared to grass silage due to their lower fiber concentration. Dietary lipids can be effective in reducing CH4 emissions, but their applicability will depend on effects on feed intake, fiber digestibility, production, and milk composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease CH4 emission intensity (Ei; CH4 per unit animal product), particularly when inclusion is above 40% of dietary dry matter and rumen function is not impaired. Supplementation of diets containing medium to poor quality forages with small amounts of concentrate feed will typically decrease CH4 Ei. Nitrates show promise as CH4 mitigation agents, but more studies are needed to fully understand their impact on whole-farm greenhouse gas emissions, animal productivity, and animal health. Through their effect on feed efficiency and rumen stoichiometry, ionophores are likely to have a moderate CH4 mitigating effect in ruminants fed high-grain or mixed grain–forage diets. Tannins may also reduce CH4 emissions although in some situations intake and milk production may be compromised. Some direct-fed microbials, such as yeast-based products, might have a moderate CH4–mitigating effect through increasing animal productivity and feed efficiency, but the effect is likely to be inconsistent. Vaccines against rumen archaea may offer mitigation opportunities in the future although the extent of CH4 reduction is likely to be small and adaptation by ruminal microbes and persistence of the effect is unknown. Overall, improving forage quality and the overall efficiency of dietary nutrient use is an effective way of decreasing CH4 Ei. Several feed supplements have a potential to reduce CH4 emission from ruminants although their long-term effect has not been well established and some are toxic or may not be economically feasible.
Mitigation of methane and nitrous oxide emissions from animal operations: II. A review of manure management mitigation options
Montes, F. ; Meinen, R. ; Dell, C. ; Rotz, A. ; Hristov, A.N. ; Oh, J. ; Waghorn, G. ; Gerber, P.J. ; Henderson, B.L. ; Makkar, H.P.S. ; Dijkstra, J. - \ 2013
Journal of Animal Science 91 (2013)11. - ISSN 0021-8812 - p. 5070 - 5094.
greenhouse-gas emissions - dietary crude protein - lactating dairy-cows - environmental systems-analysis - organic-carbon sequestration - phase compost biofilters - swine manure - ammonia emissions - anaerobic-digestion - cattle slurry
This review analyzes published data on manure management practices used to mitigate methane (CH4) and nitrous oxide (N2O) emissions from animal operations. Reducing excreted nitrogen (N) and degradable organic carbon (C) by diet manipulation to improve the balance of nutrient inputs with production is an effective practice to reduce CH4 and N2O emissions. Most CH4 is produced during manure storage; therefore, reducing storage time, lowering manure temperature by storing it outside during colder seasons, and capturing and combusting the CH4 produced during storage are effective practices to reduce CH4 emission. Anaerobic digestion with combustion of the gas produced is effective in reducing CH4 emission and organic C content of manure; this increases readily available C and N for microbial processes creating little CH4 and increased N2O emissions following land application. Nitrous oxide emission occurs following land application as a byproduct of nitrification and dentrification processes in the soil, but these processes may also occur in compost, biofilter materials, and permeable storage covers. These microbial processes depend on temperature, moisture content, availability of easily degradable organic C, and oxidation status of the environment, which make N2O emissions and mitigation results highly variable. Managing the fate of ammoniacal N is essential to the success of N2O and CH4 mitigation because ammonia is an important component in the cycling of N through manure, soil, crops, and animal feeds. Manure application techniques such as subsurface injection reduce ammonia and CH4 emissions but can result in increased N2O emissions. Injection works well when combined with anaerobic digestion and solids separation by improving infiltration. Additives such as urease and nitrification inhibitors that inhibit microbial processes have mixed results but are generally effective in controlling N2O emission from intensive grazing systems. Matching plant nutrient requirements with manure fertilization, managing grazing intensity, and using cover crops are effective practices to increase plant N uptake and reduce N2O emissions. Due to system interactions, mitigation practices that reduce emissions in one stage of the manure management process may increase emissions elsewhere, so mitigation practices must be evaluated at the whole farm level.
Technical options for the mitigation of direct methane and nitrous oxide emissions from livestock: a review
Gerber, P.J. ; Hristov, A.N. ; Henderson, B.L. ; Makkar, H.P.S. ; Oh, J. ; Lee, C. ; Meinen, R. ; Montes, F. ; Ott, T. ; Firkins, J. ; Rotz, A. ; Dell, C. ; Adesogan, A.T. ; Yang, W.Z. ; Tricarico, J.M. ; Kebreab, E. ; Waghorn, G. ; Dijkstra, J. ; Oosting, S.J. - \ 2013
Animal 7 (2013)s2. - ISSN 1751-7311 - p. 220 - 234.
greenhouse-gas emissions - dietary nitrate supplementation - phase compost biofilters - lactating dairy-cows - cereal grain diet - nitrification inhibitors - reduce methane - pig slurry - management options - rumen fermentation
Although livestock production accounts for a sizeable share of global greenhouse gas emissions, numerous technical options have been identified to mitigate these emissions. In this review, a subset of these options, which have proven to be effective, are discussed. These include measures to reduce CH4 emissions from enteric fermentation by ruminants, the largest single emission source from the global livestock sector, and for reducing CH4 and N2O emissions from manure. A unique feature of this review is the high level of attention given to interactions between mitigation options and productivity. Among the feed supplement options for lowering enteric emissions, dietary lipids, nitrates and ionophores are identified as the most effective. Forage quality, feed processing and precision feeding have the best prospects among the various available feed and feed management measures. With regard to manure, dietary measures that reduce the amount of N excreted (e.g. better matching of dietary protein to animal needs), shift N excretion from urine to faeces (e.g. tannin inclusion at low levels) and reduce the amount of fermentable organic matter excreted are recommended. Among the many ‘end-of-pipe’ measures available for manure management, approaches that capture and/or process CH4 emissions during storage (e.g. anaerobic digestion, biofiltration, composting), as well as subsurface injection of manure, are among the most encouraging options flagged in this section of the review. The importance of a multiple gas perspective is critical when assessing mitigation potentials, because most of the options reviewed show strong interactions among sources of greenhouse gas (GHG) emissions. The paper reviews current knowledge on potential pollution swapping, whereby the reduction of one GHG or emission source leads to unintended increases in another
Mitigation of greenhouse gas emissions in livestock production - A review of technical options for non-CO2 emissions
Hristov, A.N. ; Oh, J. ; Lee, C. ; Meinen, R. ; Montes, F. ; Ott, T. ; Firkins, J. ; Rotz, A. ; Dell, C. ; Adesogan, C. ; Yang, W. ; Tricarico, J. ; Kebreab, E. ; Waghorn, G. ; Dijkstra, J. ; Oosting, S.J. - \ 2013
Rome : FAO (FAO animal production and health paper 177) - ISBN 9789251076583 - 231
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