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Prof. Dr. Thomas Amon
Leibniz-Institut für Agrartechnik und Bioökonomie e. V. , Head of Department Engineering for Livestock Management

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0 Animal Welfare
0 Manure management
0 Livestock Science
0 Modelling and Simulation
0 Animal Husbandry

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Journal article
Published: 10 August 2021 in Agronomy
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With an increasing number of naturally ventilated dairy barns (NVDBs), the emission of ammonia and greenhouse gases into the surrounding environment is expected to increase as well. It is very challenging to accurately determine the amount of gases released from a NVDB on-farm. Moreover, control options for the micro-climate to increase animal welfare are limited in an NVDB at present. Both issues are due to the complexity of the NVDB micro-environment, which is subject to temporal (such as wind direction and temperature) and spatial (such as openings and animals acting as airflow obstacles) fluctuations. The air exchange rate (AER) is one of the most valuable evaluation entities, since it is directly related to the gas emission rate and animal welfare. In this context, our study determined the general and local AERs of NVDBs of different shapes under diverse airflow conditions. Previous works identified main influencing parameters for the general AER and mathematically linked them together to predict the AER of the barn as a whole. The present research study is a continuation and extension of previous studies about the determination of AER. It provides new insights into the influence of convection flow regimes. In addition, it goes further in precision by determining the local AERs, depending on the position of the considered volume inside the barn. After running several computational fluid dynamics (CFD) simulations, we used the statistical tool of general linear modeling in order to identify quantitative relationships between the AER and the following five influencing parameters, the length/width ratio of the barn, the side opening configuration, the airflow temperature, magnitude and incoming direction. The work succeeded in taking the temperature into account as a further influencing parameter in the model and, thus, for the first time, in analysing the effect of the different types of flow convection in this context. The resulting equations predict the barn AER with an R2 equals 0.98 and the local AER with a mean R2 equals around 0.87. The results go a step further in the precise determination of the AER of NVDB and, therefore, are of fundamental importance for a better and deeper understanding of the interaction between the driving forces of AER in NVDB.

ACS Style

E. Doumbia; David Janke; Qianying Yi; Alexander Prinz; Thomas Amon; Martin Kriegel; Sabrina Hempel. A Parametric Model for Local Air Exchange Rate of Naturally Ventilated Barns. Agronomy 2021, 11, 1585 .

AMA Style

E. Doumbia, David Janke, Qianying Yi, Alexander Prinz, Thomas Amon, Martin Kriegel, Sabrina Hempel. A Parametric Model for Local Air Exchange Rate of Naturally Ventilated Barns. Agronomy. 2021; 11 (8):1585.

Chicago/Turabian Style

E. Doumbia; David Janke; Qianying Yi; Alexander Prinz; Thomas Amon; Martin Kriegel; Sabrina Hempel. 2021. "A Parametric Model for Local Air Exchange Rate of Naturally Ventilated Barns." Agronomy 11, no. 8: 1585.

Review
Published: 13 July 2021 in Microorganisms
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The Streptococcus genus belongs to one of the major pathogen groups inducing bovine mastitis. In the dairy industry, mastitis is the most common and costly disease. It not only negatively impacts economic profit due to milk losses and therapy costs, but it is an important animal health and welfare issue as well. This review describes a classification, reservoirs, and frequencies of the most relevant Streptococcus species inducing bovine mastitis (S. agalactiae, S. dysgalactiae and S. uberis). Host and environmental factors influencing mastitis susceptibility and infection rates will be discussed, because it has been indicated that Streptococcus herd prevalence is much higher than mastitis rates. After infection, we report the sequence of cow immune reactions and differences in virulence factors of the main Streptococcus species. Different mastitis detection techniques together with possible conventional and alternative therapies are described. The standard approach treating streptococcal mastitis is the application of ß-lactam antibiotics. In streptococci, increased antimicrobial resistance rates were identified against enrofloxacin, tetracycline, and erythromycin. At the end, control and prevention measures will be considered, including vaccination, hygiene plan, and further interventions. It is the aim of this review to estimate the contribution and to provide detailed knowledge about the role of the Streptococcus genus in bovine mastitis.

ACS Style

Tina Kabelitz; Etienne Aubry; Kira van Vorst; Thomas Amon; Marcus Fulde. The Role of Streptococcus spp. in Bovine Mastitis. Microorganisms 2021, 9, 1497 .

AMA Style

Tina Kabelitz, Etienne Aubry, Kira van Vorst, Thomas Amon, Marcus Fulde. The Role of Streptococcus spp. in Bovine Mastitis. Microorganisms. 2021; 9 (7):1497.

Chicago/Turabian Style

Tina Kabelitz; Etienne Aubry; Kira van Vorst; Thomas Amon; Marcus Fulde. 2021. "The Role of Streptococcus spp. in Bovine Mastitis." Microorganisms 9, no. 7: 1497.

Review
Published: 17 May 2021 in Applied Sciences
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The tracer gas method is one of the common ways to evaluate the air exchange rate in a naturally ventilated barn. One crucial condition for the accuracy of the method is that both considered gases (pollutant and tracer) are perfectly mixed at the points where the measurements are done. In the present study, by means of computational fluids dynamics (CFD), the mixing ratio NH3/CO2 is evaluated inside a barn in order to assess under which flow conditions the common height recommendation guidelines for sampling points (sampling line and sampling net) of the tracer gas method are most valuable. Our CFD model considered a barn with a rectangular layout and four animal-occupied zones modeled as a porous medium representing pressure drop and heat entry from lying and standing cows. We studied three inflow angles and six combinations of air inlet wind speed and temperatures gradients covering the three types of convection, i.e., natural, mixed, and forced. Our results showed that few cases corresponded to a nearly perfect gas mixing ratio at the currently common recommendation of at least a 3 m measurement height, while the best height in fact lied between 1.5 m and 2.5 m for most cases.

ACS Style

E. Doumbia; David Janke; Qianying Yi; Guoqiang Zhang; Thomas Amon; Martin Kriegel; Sabrina Hempel. On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB. Applied Sciences 2021, 11, 4560 .

AMA Style

E. Doumbia, David Janke, Qianying Yi, Guoqiang Zhang, Thomas Amon, Martin Kriegel, Sabrina Hempel. On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB. Applied Sciences. 2021; 11 (10):4560.

Chicago/Turabian Style

E. Doumbia; David Janke; Qianying Yi; Guoqiang Zhang; Thomas Amon; Martin Kriegel; Sabrina Hempel. 2021. "On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB." Applied Sciences 11, no. 10: 4560.

Journal article
Published: 05 February 2021 in Biosystems Engineering
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Ammonia emissions damage the environment and have negative consequences for human and animal health. In the German livestock sector, most ammonia emissions come from naturally ventilated dairy barns. To reduce emissions, Germany has signed the EU Directive 2016/2284 to achieve a stepwise decrease in the ammonia emissions ceiling. The aim of this study was to investigate the seasonal mitigation effect of a urease inhibitor under practical conditions and provide information relating to two theoretical application scenarios in order to estimate an annual application scenario. The experimental design was conducted according to the requirements of the Verification of Environmental Technologies for Agricultural Production test protocol using the CO2 balance method to obtain the emissions. In a manual process, the inhibitor was applied to the floor surfaces of two dairy farms. The application took place once a day over three days during summer, winter and the transition period (spring/autumn). The ready-to-use liquid formulation of 1% inhibitor K dissolved in pyrrolidone was mixed with water resulting in 2.5 mg m−2 application rate of inhibitor and 50 ml m−2 water. The ammonia emissions on Farm A and Farm B were reduced by 40% and 53% in summer, 65% and 68% in winter and 64% and 54% in transition period, respectively. Thus, an annual reduction of 58% on Farm A and 57% on Farm B was observed. In a theoretical scenario where no inhibitor was applied during winter, up to 41% of the annual reduction was observed.

ACS Style

Anna B. Bobrowski; Diliara Willink; David Janke; Thomas Amon; Frauke Hagenkamp-Korth; Mario Hasler; Eberhard Hartung. Reduction of ammonia emissions by applying a urease inhibitor in naturally ventilated dairy barns. Biosystems Engineering 2021, 204, 104 -114.

AMA Style

Anna B. Bobrowski, Diliara Willink, David Janke, Thomas Amon, Frauke Hagenkamp-Korth, Mario Hasler, Eberhard Hartung. Reduction of ammonia emissions by applying a urease inhibitor in naturally ventilated dairy barns. Biosystems Engineering. 2021; 204 ():104-114.

Chicago/Turabian Style

Anna B. Bobrowski; Diliara Willink; David Janke; Thomas Amon; Frauke Hagenkamp-Korth; Mario Hasler; Eberhard Hartung. 2021. "Reduction of ammonia emissions by applying a urease inhibitor in naturally ventilated dairy barns." Biosystems Engineering 204, no. : 104-114.

Journal article
Published: 31 October 2020 in Sensors
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The direct measurement of emissions from naturally ventilated dairy barns is challenging due to their large openings and the turbulent and unsteady airflow at the inlets and outlets. The aim of this study was to quantify the impacts of the number and positions of sensors on the estimation of volume flow rate and emissions. High resolution measurements of a naturally ventilated scaled building model in an atmospheric boundary layer wind tunnel were done. Tracer gas was released inside the model and measured at the outlet area, using a fast flame ionization detector (FFID). Additionally, the normal velocity on the area was measured using laser Doppler anemometry (LDA). In total, for a matrix of 65 × 4 sensor positions, the mean normal velocities and the mean concentrations were measured and used to calculate the volume flow rate and the emissions. This dataset was used as a reference to assess the accuracy while systematically reducing the number of sensors and varying the positions of them. The results showed systematic errors in the emission estimation up to + 97%, when measurements of concentration and velocity were done at one constant height. This error could be lowered under 5%, when the concentrations were measured as a vertical composite sample.

ACS Style

David Janke; Qianying Yi; Lars Thormann; Sabrina Hempel; Barbara Amon; Štěpán Nosek; Philippe Van Van Overbeke; Thomas Amon. Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building. Sensors 2020, 20, 6223 .

AMA Style

David Janke, Qianying Yi, Lars Thormann, Sabrina Hempel, Barbara Amon, Štěpán Nosek, Philippe Van Van Overbeke, Thomas Amon. Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building. Sensors. 2020; 20 (21):6223.

Chicago/Turabian Style

David Janke; Qianying Yi; Lars Thormann; Sabrina Hempel; Barbara Amon; Štěpán Nosek; Philippe Van Van Overbeke; Thomas Amon. 2020. "Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building." Sensors 20, no. 21: 6223.

Journal article
Published: 03 October 2020 in Applied Sciences
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A reliable quantification of greenhouse gas emissions is a basis for the development of adequate mitigation measures. Protocols for emission measurements and data analysis approaches to extrapolate to accurate annual emission values are a substantial prerequisite in this context. We systematically analyzed the benefit of supervised machine learning methods to project methane emissions from a naturally ventilated cattle building with a concrete solid floor and manure scraper located in Northern Germany. We took into account approximately 40 weeks of hourly emission measurements and compared model predictions using eight regression approaches, 27 different sampling scenarios and four measures of model accuracy. Data normalization was applied based on median and quartile range. A correlation analysis was performed to evaluate the influence of individual features. This indicated only a very weak linear relation between the methane emission and features that are typically used to predict methane emission values of naturally ventilated barns. It further highlighted the added value of including day-time and squared ambient temperature as features. The error of the predicted emission values was in general below 10%. The results from Gaussian processes, ordinary multilinear regression and neural networks were least robust. More robust results were obtained with multilinear regression with regularization, support vector machines and particularly the ensemble methods gradient boosting and random forest. The latter had the added value to be rather insensitive against the normalization procedure. In the case of multilinear regression, also the removal of not significantly linearly related variables (i.e., keeping only the day-time component) led to robust modeling results. We concluded that measurement protocols with 7 days and six measurement periods can be considered sufficient to model methane emissions from the dairy barn with solid floor with manure scraper, particularly when periods are distributed over the year with a preference for transition periods. Features should be normalized according to median and quartile range and must be carefully selected depending on the modeling approach.

ACS Style

Sabrina Hempel; Julian Adolphs; Niels Landwehr; Dilya Willink; David Janke; Thomas Amon. Supervised Machine Learning to Assess Methane Emissions of a Dairy Building with Natural Ventilation. Applied Sciences 2020, 10, 6938 .

AMA Style

Sabrina Hempel, Julian Adolphs, Niels Landwehr, Dilya Willink, David Janke, Thomas Amon. Supervised Machine Learning to Assess Methane Emissions of a Dairy Building with Natural Ventilation. Applied Sciences. 2020; 10 (19):6938.

Chicago/Turabian Style

Sabrina Hempel; Julian Adolphs; Niels Landwehr; Dilya Willink; David Janke; Thomas Amon. 2020. "Supervised Machine Learning to Assess Methane Emissions of a Dairy Building with Natural Ventilation." Applied Sciences 10, no. 19: 6938.

Journal article
Published: 01 September 2020 in Applied Sciences
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Airflow inside naturally ventilated dairy (NVD) buildings is highly variable and difficult to understand due to the lack of precious measuring techniques with the existing methods. Computational fluid dynamics (CFD) was applied to investigate the effect of different seasonal opening combinations of an NVD building on airflow patterns and airflow rate inside the NVD building as an alternative to full scale and scale model experiments. ANSYS 2019R2 was used for creating model geometry, meshing, and simulation. Eight ventilation opening combinations and 10 different reference air velocities were used for the series of simulation. The data measured in a large boundary layer wind tunnel using a 1:100 scale model of the NVD building was used for CFD model validation. The results show that CFD using standard k-ε turbulence model was capable of simulating airflow in and outside of the NVD building. Airflow patterns were different for different opening scenarios at the same external wind speed, which may affect cow comfort and gaseous emissions. Guiding inlet air by controlling openings may ensure animal comfort and minimize emissions. Non-isothermal and transient simulations of NVD buildings should be carried out for better understanding of airflow patterns.

ACS Style

Chayan Kumer Saha; Qianying Yi; David Janke; Sabrina Hempel; Barbara Amon; Thomas Amon. Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study. Applied Sciences 2020, 10, 6054 .

AMA Style

Chayan Kumer Saha, Qianying Yi, David Janke, Sabrina Hempel, Barbara Amon, Thomas Amon. Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study. Applied Sciences. 2020; 10 (17):6054.

Chicago/Turabian Style

Chayan Kumer Saha; Qianying Yi; David Janke; Sabrina Hempel; Barbara Amon; Thomas Amon. 2020. "Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study." Applied Sciences 10, no. 17: 6054.

Journal article
Published: 11 August 2020 in Biosystems Engineering
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Emissions and ventilation rates (VRs) in naturally ventilated dairy barns (NVDBs) are usually measured using indirect methods, where the choice of inside and outside sampling locations (i.e. sampling strategy) is crucial. The goal of this study was to quantify the influence of the sampling strategy on the estimation of emissions and VRs. We equipped a NVDB in northern Germany with an extensive measuring setup capable of measuring emissions under all wind conditions. Ammonia (NH3) and carbon dioxide (CO2) concentrations were measured with two Fourier-transform infrared spectrometers. Hourly values for ventilation rates and emissions for ammonia over a period of nearly a year were derived using the CO2 balance method and five different sampling strategies for the acquisition of indoor and outdoor concentrations were applied. When comparing the strategy estimating the highest emission level to the strategy estimating the lowest, the differences in NH3 emissions in winter, transition, and summer season were +26%, +19% and +11%, respectively. For the ventilation rates, the differences were +80%, +94%, and 63% for the winter, transition and summer season, respectively. By accommodating inside/outside concentration measurements around the entire perimeter of the barn instead of a reduced part of the perimeter (aligned to a presumed main wind direction), the amount of available data substantially increased for around 210% for the same monitoring period.

ACS Style

David Janke; Dylia Willink; Christian Ammon; Sabrina Hempel; Sabine Schrade; Peter Demeyer; Eberhard Hartung; Barbara Amon; Nico Ogink; Thomas Amon. Calculation of ventilation rates and ammonia emissions: Comparison of sampling strategies for a naturally ventilated dairy barn. Biosystems Engineering 2020, 198, 15 -30.

AMA Style

David Janke, Dylia Willink, Christian Ammon, Sabrina Hempel, Sabine Schrade, Peter Demeyer, Eberhard Hartung, Barbara Amon, Nico Ogink, Thomas Amon. Calculation of ventilation rates and ammonia emissions: Comparison of sampling strategies for a naturally ventilated dairy barn. Biosystems Engineering. 2020; 198 ():15-30.

Chicago/Turabian Style

David Janke; Dylia Willink; Christian Ammon; Sabrina Hempel; Sabine Schrade; Peter Demeyer; Eberhard Hartung; Barbara Amon; Nico Ogink; Thomas Amon. 2020. "Calculation of ventilation rates and ammonia emissions: Comparison of sampling strategies for a naturally ventilated dairy barn." Biosystems Engineering 198, no. : 15-30.

Journal article
Published: 17 July 2020 in Applied Sciences
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The application of naturally ventilated pig buildings (NVPBs) with outdoor exercise yards is on the rise mainly due to animal welfare considerations, while the issue of emissions from the buildings to the surrounding environment is important. Since air pollutants are mainly transported by airflow, the knowledge on the airflow characteristics downwind the building is required. The objective of this research was to investigate airflow properties downwind of a NVPB with a roofed outdoor exercise yard for roof slopes of 5°, 15°, and 25°. Air velocities downwind a 1:50 scaled NVPB model were measured using a Laser Doppler Anemometer in a large boundary layer wind tunnel. A region with reduced mean air velocities was found along the downwind side of the building with a distance up to 0.5 m (i.e., 3.8 times building height), in which the emission concentration might be high. Additional air pollutant treatment technologies applied in this region might contribute to emission mitigation effectively. Furthermore, a wake zone with air recirculation was observed in this area. A smaller roof slope (i.e., 5° slope) resulted in a higher and shorter wake zone and thus a shorter air pollutant dispersion distance.

ACS Style

Qianying Yi; David Janke; Lars Thormann; Guoqiang Zhang; Barbara Amon; Sabrina Hempel; Štěpán Nosek; Eberhard Hartung; Thomas Amon. Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution. Applied Sciences 2020, 10, 4931 .

AMA Style

Qianying Yi, David Janke, Lars Thormann, Guoqiang Zhang, Barbara Amon, Sabrina Hempel, Štěpán Nosek, Eberhard Hartung, Thomas Amon. Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution. Applied Sciences. 2020; 10 (14):4931.

Chicago/Turabian Style

Qianying Yi; David Janke; Lars Thormann; Guoqiang Zhang; Barbara Amon; Sabrina Hempel; Štěpán Nosek; Eberhard Hartung; Thomas Amon. 2020. "Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution." Applied Sciences 10, no. 14: 4931.

Preprint
Published: 30 June 2020
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The application of naturally ventilated pig buildings (NVPBs) with outdoor exercise yards is on the rise mainly due to animal welfare considerations, while the issue of emissions from the buildings to the surrounding environment is important. Since air pollutants are mainly transported by airflow, the knowledge on the airflow characteristics downwind the building is required. The objective of this research was to investigate airflow properties downwind of a NVPB with a roofed outdoor exercise yard for roof slopes of 5°, 15°, and 25°. Air velocities downwind a 1:50 scaled NVPB model were measured using a Laser Doppler Anemometer in a large boundary layer wind tunnel. A region with reduced mean air velocities was found along the downwind side of the building with a distance up to 0.5 m (i.e. 3.8 times building height), in which the emission concentration might be high. It was found that a smaller roof slope (i.e. 5° slope) resulted in a higher and shorter wake zone and thus a shorter air pollutant dispersion distance. It was concluded that a smaller roof slope could contribute to the dilution of air pollutants and a lower air pollutant concentration near the ground.

ACS Style

Qianying Yi; David Janke; Lars Thormann; Guoqiang Zhang; Barbara Amon; Sabrina Hempel; Štěpán Nosek; Eberhard Hartung; Thomas Amon. Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution. 2020, 1 .

AMA Style

Qianying Yi, David Janke, Lars Thormann, Guoqiang Zhang, Barbara Amon, Sabrina Hempel, Štěpán Nosek, Eberhard Hartung, Thomas Amon. Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution. . 2020; ():1.

Chicago/Turabian Style

Qianying Yi; David Janke; Lars Thormann; Guoqiang Zhang; Barbara Amon; Sabrina Hempel; Štěpán Nosek; Eberhard Hartung; Thomas Amon. 2020. "Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution." , no. : 1.

Journal article
Published: 18 June 2020 in Computers and Electronics in Agriculture
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Two transient open source solvers, OpenFOAM and ParMooN, and the commercial solver Ansys Fluent are assessed with respect to the simulation of the turbulent air flow inside and around a dairy barn. For this purpose, data were obtained in an experimental campaign at a 1:100 scaled wind tunnel model. All solvers used different meshes, discretization schemes, and turbulence models. The experimental data and numerical results agree well for time-averaged stream-wise and vertical-wise velocities. In particular, the air exchange was predicted with high accuracy by both open source solvers with relative differences less than 4% and by the commercial solver with a relative difference of 9% compared to the experimental results. With respect to the turbulent quantities, good agreements at the second (downwind) half of the barn inside and especially outside the barn could be achieved, where all codes accurately predicted the flow separation and, in many cases, the root-mean-square velocities. Deviations between simulations and experimental results regarding turbulent quantities could be observed in the first part of the barn. These deviations can be attributed to the utilization of roughness elements between inlet and barn in the experiment that were not modeled in the numerical simulations. Both open source solvers proved to be promising tools for the accurate prediction of time-dependent phenomena in an agricultural context, e.g., like the transport of particulate matter or pathogen-laden aerosols in and around agricultural buildings.

ACS Style

David Janke; Alfonso Caiazzo; Naveed Ahmed; Najib Alia; Oswald Knoth; Baptiste Moreau; Ulrich Wilbrandt; Dilya Willink; Thomas Amon; Volker John. On the feasibility of using open source solvers for the simulation of a turbulent air flow in a dairy barn. Computers and Electronics in Agriculture 2020, 175, 105546 .

AMA Style

David Janke, Alfonso Caiazzo, Naveed Ahmed, Najib Alia, Oswald Knoth, Baptiste Moreau, Ulrich Wilbrandt, Dilya Willink, Thomas Amon, Volker John. On the feasibility of using open source solvers for the simulation of a turbulent air flow in a dairy barn. Computers and Electronics in Agriculture. 2020; 175 ():105546.

Chicago/Turabian Style

David Janke; Alfonso Caiazzo; Naveed Ahmed; Najib Alia; Oswald Knoth; Baptiste Moreau; Ulrich Wilbrandt; Dilya Willink; Thomas Amon; Volker John. 2020. "On the feasibility of using open source solvers for the simulation of a turbulent air flow in a dairy barn." Computers and Electronics in Agriculture 175, no. : 105546.

Journal article
Published: 25 May 2020 in Sustainability
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The mandate to limit global temperature rise calls for a reliable quantification of gaseous pollutant emissions as a basis for effective mitigation. Methane emissions from ruminant fermentation are of particular relevance in the context of greenhouse gas mitigation. The emission dynamics are so far insufficiently understood. We analyzed hourly methane emission data collected during contrasting seasons from two naturally ventilated dairy cattle buildings with concrete floor and performed a second order polynomial regression. We found a parabolic temperature dependence of the methane emissions irrespective of the measurement site and setup. The position of the parabola vertex varied when considering different hours of the day. The circadian rhythm of methane emissions was represented by the pattern of the fitted values of the constant term of the polynomial and could be well explained by feeding management and air flow conditions. We found barn specific emission minima at ambient temperatures around 10 °C to 15 °C. As this identified temperature optimum coincides with the welfare temperature of dairy cows, we concluded that temperature regulation of dairy cow buildings with concrete floor should be considered and further investigated as an emission mitigation measure. Our results further indicated that empirical modeling of methane emissions from the considered type of buildings with a second order polynomial for the independent variable air temperature can increase the accuracy of predicted long-term emission values for regions with pronounced seasonal temperature fluctuations.

ACS Style

Sabrina Hempel; Diliara Willink; David Janke; Christian Ammon; Barbara Amon; Thomas Amon. Methane Emission Characteristics of Naturally Ventilated Cattle Buildings. Sustainability 2020, 12, 4314 .

AMA Style

Sabrina Hempel, Diliara Willink, David Janke, Christian Ammon, Barbara Amon, Thomas Amon. Methane Emission Characteristics of Naturally Ventilated Cattle Buildings. Sustainability. 2020; 12 (10):4314.

Chicago/Turabian Style

Sabrina Hempel; Diliara Willink; David Janke; Christian Ammon; Barbara Amon; Thomas Amon. 2020. "Methane Emission Characteristics of Naturally Ventilated Cattle Buildings." Sustainability 12, no. 10: 4314.

Journal article
Published: 07 February 2020 in Waste Management
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Antibiotic-resistant bacteria are a threat to human and animal health. In recent years, the presence of extended-spectrum-β-lactamase (ESBL)-producing Escherichia (E.) coli in chicken manure, which is used as organic fertilizer, is a concern. The aim of the present study was to determine the effects of the carbon/nitrogen (C/N) ratio and moisture content (MC) on the survival of ESBL-producing E. coli during laboratory-scale composting of chicken manure. Nine different compost mixtures were enriched with an ESBL-producing E. coli strain to an initial concentration of 7 log10 CFU/g, and the number of E. coli, temperature, and chemical conditions during composting were determined. The fastest decrease in E. coli occurred for all mixtures with a C/N ratio of 10:1. Additionally, dry mixtures with an MC of 20% and a C/N ratio of either 10:1 or 40:1 exhibited faster reductions in E. coli than the moist mixtures did, despite having lower maximum temperatures within the bioreactors. The decimal reduction times ranged from 0.27 days in a mixture with a C/N ratio of 10:1 and 40% MC to 4.82 days in a mixture with a C/N ratio of 40:1 and 40% MC. Both the C/N ratio and MC had a significant effect on the number of ESBL-producing E. coli and on temperature development; the C/N ratio additionally affected the pH value and content of ammoniacal nitrogen during chicken manure composting. The results of this study demonstrate a considerable range of mechanisms involved in the inactivation of E. coli during chicken manure composting.

ACS Style

Corinna Thomas; Christine Idler; Christian Ammon; Thomas Amon. Effects of the C/N ratio and moisture content on the survival of ESBL-producing Escherichia coli during chicken manure composting. Waste Management 2020, 105, 110 -118.

AMA Style

Corinna Thomas, Christine Idler, Christian Ammon, Thomas Amon. Effects of the C/N ratio and moisture content on the survival of ESBL-producing Escherichia coli during chicken manure composting. Waste Management. 2020; 105 ():110-118.

Chicago/Turabian Style

Corinna Thomas; Christine Idler; Christian Ammon; Thomas Amon. 2020. "Effects of the C/N ratio and moisture content on the survival of ESBL-producing Escherichia coli during chicken manure composting." Waste Management 105, no. : 110-118.

Journal article
Published: 01 February 2020 in Journal of Thermal Biology
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The severity of heat stress conditions in high-yielding dairy cows is currently underestimated. The present study aimed to determine the heat load threshold of the temperature-humidity index (THI) on physiological parameters of lactating Holstein-Friesian cows under a continental climatic zone in Germany. Physiological parameter measurements, such as respiration rate (RR), measured hourly, and heart rate (HR) and rectal temperature (RT), both measured twice daily, were performed in a total of 139 multiparous cows on three randomly chosen measurement days per week. In addition, the ambient temperature and relative humidity of the barn were recorded every 5 min to calculate the current THI. The physiological parameter data were linked to the THI, and the heat load thresholds were determined using the broken-stick model. The heat load duration effect of each physiological parameter was obtained by regression analysis. Considering the increases in the physiological parameters, our study provided reliable data to determine heat load thresholds for lactating high-yielding dairy cows in a moderate climatic zone. The heat load threshold could be determined for RR in standing cows (THI = 70) and lying cows (THI = 65) and for HR (THI = 72) and RT (THI = 70) in standing cows. The heat load duration also demonstrated a significant effect on the increases in physiological parameters among dairy cows. In particular, the present study enabled a strategy to be devised to initiate heat mitigation in high-yielding dairy cows when they are exposed to THIs above 65.

ACS Style

Severino Pinto; Gundula Hoffmann; Christian Ammon; Thomas Amon. Critical THI thresholds based on the physiological parameters of lactating dairy cows. Journal of Thermal Biology 2020, 88, 102523 .

AMA Style

Severino Pinto, Gundula Hoffmann, Christian Ammon, Thomas Amon. Critical THI thresholds based on the physiological parameters of lactating dairy cows. Journal of Thermal Biology. 2020; 88 ():102523.

Chicago/Turabian Style

Severino Pinto; Gundula Hoffmann; Christian Ammon; Thomas Amon. 2020. "Critical THI thresholds based on the physiological parameters of lactating dairy cows." Journal of Thermal Biology 88, no. : 102523.

Journal article
Published: 31 January 2020 in Sustainability
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Environmental protection efforts can only be effective in the long term with a reliable quantification of pollutant gas emissions as a first step to mitigation. Measurement and analysis strategies must permit the accurate extrapolation of emission values. We systematically analyzed the added value of applying modern machine learning methods in the process of monitoring emissions from naturally ventilated livestock buildings to the atmosphere. We considered almost 40 weeks of hourly emission values from a naturally ventilated dairy cattle barn in Northern Germany. We compared model predictions using 27 different scenarios of temporal sampling, multiple measures of model accuracy, and eight different regression approaches. The error of the predicted emission values with the tested measurement protocols was, on average, well below 20%. The sensitivity of the prediction to the selected training dataset was worse for the ordinary multilinear regression. Gradient boosting and random forests provided the most accurate and robust emission value predictions, accompanied by the second-smallest model errors. Most of the highly ranked scenarios involved six measurement periods, while the scenario with the best overall performance was: One measurement period in summer and three in the transition periods, each lasting for 14 days.

ACS Style

Sabrina Hempel; Julian Adolphs; Niels Landwehr; David Janke; Thomas Amon. How the Selection of Training Data and Modeling Approach Affects the Estimation of Ammonia Emissions from a Naturally Ventilated Dairy Barn—Classical Statistics versus Machine Learning. Sustainability 2020, 12, 1030 .

AMA Style

Sabrina Hempel, Julian Adolphs, Niels Landwehr, David Janke, Thomas Amon. How the Selection of Training Data and Modeling Approach Affects the Estimation of Ammonia Emissions from a Naturally Ventilated Dairy Barn—Classical Statistics versus Machine Learning. Sustainability. 2020; 12 (3):1030.

Chicago/Turabian Style

Sabrina Hempel; Julian Adolphs; Niels Landwehr; David Janke; Thomas Amon. 2020. "How the Selection of Training Data and Modeling Approach Affects the Estimation of Ammonia Emissions from a Naturally Ventilated Dairy Barn—Classical Statistics versus Machine Learning." Sustainability 12, no. 3: 1030.

Journal article
Published: 27 January 2020 in Computers and Electronics in Agriculture
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The discharge coefficient (Cd) is a characteristic parameter of an opening, which represents the effect of flow contraction and frictional losses when the flow goes across the opening. It is an important parameter for the ventilation rate determination when using the orifice equation method. The objectives of this study were to investigate the relationship between Cd and its potential influencing factors, i.e. opening ratio (r), building length to width ratio (α), wind speed (U), and wind direction (θ), and to evaluate the sensitivity of each factor on the Cd for naturally ventilated dairy buildings (NVDBs). The investigations were performed using the response surface methodology together with Box-Behnken Design and Computational Fluid Dynamics simulation methods. A second-order polynomial response surface model for the estimation of the discharge coefficient was developed and verified. The results showed that the Cd was significantly affected by the individual factors of r and θ, with more sensitivity to r when r > 42.5%. By contrast, the effects from the individual factors of α and U on Cd were insignificant. In addition, the interaction effects between r and θ, and between α and θ on Cd were also identified. It was concluded that the effects from both individual factors and interactions are required to be considered in the estimation of the opening discharge coefficient for NVDBs.

ACS Style

Qianying Yi; Guoqiang Zhang; Hao Li; Xiaoshuai Wang; David Janke; Barbara Amon; Sabrina Hempel; Thomas Amon. Estimation of opening discharge coefficient of naturally ventilated dairy buildings by response surface methodology. Computers and Electronics in Agriculture 2020, 169, 105224 .

AMA Style

Qianying Yi, Guoqiang Zhang, Hao Li, Xiaoshuai Wang, David Janke, Barbara Amon, Sabrina Hempel, Thomas Amon. Estimation of opening discharge coefficient of naturally ventilated dairy buildings by response surface methodology. Computers and Electronics in Agriculture. 2020; 169 ():105224.

Chicago/Turabian Style

Qianying Yi; Guoqiang Zhang; Hao Li; Xiaoshuai Wang; David Janke; Barbara Amon; Sabrina Hempel; Thomas Amon. 2020. "Estimation of opening discharge coefficient of naturally ventilated dairy buildings by response surface methodology." Computers and Electronics in Agriculture 169, no. : 105224.

Journal article
Published: 03 January 2020 in Energy
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Cotton stalks (CSs) are an abundant, renewable lignocellulose residue, which is usually burnt in the field to prevent propagation of vegetal diseases, causing economic losses and environmental concerns. The production of biogas has been considered as an alternative. This work aimed to improve the biogas production from CS by steam or organosolv plus supercritical carbon dioxide (scCO2) pre-treatment. All samples were pre-treated in a 500 mL autoclave for 140 min at 180 °C and fermented in 1 L eudiometer batch digesters for 42 days at 37.5 °C. The biogas and methane yields achieved from the untreated CS were 250 and 137 norm litres per kg of volatile solid (LN kg−1 VS), respectively. Pre-treatment of the CS samples with steam or the organosolv plus scCO2 process increased the methane yield by 20% compared to the untreated samples. The highest methane yield of 177 LN kg−1 VS was achieved by organosolv plus scCO2 pre-treatment at 100 bar and 180 °C for 140 min. Moreover, pre-treatment of the CS led to a significant reduction in the optimal digestion time from 30 days to 20 days for biogas production for the untreated CS.

ACS Style

Rafat Al Afif; Martin Wendland; Thomas Amon; Christoph Pfeifer. Supercritical carbon dioxide enhanced pre-treatment of cotton stalks for methane production. Energy 2020, 194, 116903 .

AMA Style

Rafat Al Afif, Martin Wendland, Thomas Amon, Christoph Pfeifer. Supercritical carbon dioxide enhanced pre-treatment of cotton stalks for methane production. Energy. 2020; 194 ():116903.

Chicago/Turabian Style

Rafat Al Afif; Martin Wendland; Thomas Amon; Christoph Pfeifer. 2020. "Supercritical carbon dioxide enhanced pre-treatment of cotton stalks for methane production." Energy 194, no. : 116903.

Journal article
Published: 18 December 2019 in Journal of Thermal Biology
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The dairy industry in regions with moderate climates, such as Central Europe, will be increasingly challenged in the future by climate change. The problem of heat stress will especially affect dairy husbandry in naturally ventilated barns (NVB). The approach of the study was to determine a heat stress threshold of the average daily temperature-humidity index (THI) that results in changes in the daily rumination time (RT) of lactating, high-yielding cows. The data set was composed of a high sample size of 183 cows and long-duration measurements of 21240 daily observations over two years from June 2015 to May 2017, which were collected in an NVB in Groβ Kreutz, Germany. The THI was calculated in 5-min intervals by data from several sensors in different positions inside the barn. Additionally, every cow from the herd of an average of 53 cows in the experimental procedure was wearing a neck collar with a Lely Qwes HR system that provided the RT 24 h a day (12 2-h recordings were summarized). The study showed that heat stress also negatively influenced RT in moderate climates. The heat stress threshold of 52 THI was determined by broken-stick regression and indicated changes of RT of lactating dairy cows in Germany. During the experimental period, the heat stress threshold for RT was reached from April to September for up to 720 h per month. The changes in RT to the heat stress threshold will be affected by cows' characteristics. Therefore, we considered several cow-related factors, such as milk yield (MY), lactation number (LN), lactation stage (days in milk, or DIM) and pregnancy stage (P) to better understand cows’ individual reactions to heat stress. Multiparous, high-yielding cows in later lactation stages are potentially more strongly affected than other cows.

ACS Style

Theresa Müschner-Siemens; Gundula Hoffmann; Christian Ammon; Thomas Amon. Daily rumination time of lactating dairy cows under heat stress conditions. Journal of Thermal Biology 2019, 88, 102484 .

AMA Style

Theresa Müschner-Siemens, Gundula Hoffmann, Christian Ammon, Thomas Amon. Daily rumination time of lactating dairy cows under heat stress conditions. Journal of Thermal Biology. 2019; 88 ():102484.

Chicago/Turabian Style

Theresa Müschner-Siemens; Gundula Hoffmann; Christian Ammon; Thomas Amon. 2019. "Daily rumination time of lactating dairy cows under heat stress conditions." Journal of Thermal Biology 88, no. : 102484.

Research article
Published: 05 December 2019 in Earth System Dynamics
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In the last decades, a global warming trend was observed. Along with the temperature increase, modifications in the humidity and wind regime amplify the regional and local impacts on livestock husbandry. Direct impacts include the occurrence of climatic stress conditions. In Europe, cows are economically highly relevant and are mainly kept in naturally ventilated buildings that are most susceptible to climate change. The high-yielding cows are particularly vulnerable to heat stress. Modifications in housing management are the main measures taken to improve the ability of livestock to cope with these conditions. Measures are typically taken in direct reaction to uncomfortable conditions instead of in anticipation of a long-term risk for climatic stress. Measures that balance welfare, environmental and economic issues are barely investigated in the context of climate change and are thus almost not available for commercial farms. Quantitative analysis of the climate change impacts on animal welfare and linked economic and environmental factors is rare. Therefore, we used a numerical modeling approach to estimate the future heat stress risk in such dairy cattle husbandry systems. The indoor climate was monitored inside three reference barns in central Europe and the Mediterranean regions. An artificial neuronal network (ANN) was trained to relate the outdoor weather conditions provided by official meteorological weather stations to the measured indoor microclimate. Subsequently, this ANN model was driven by an ensemble of regional climate model projections with three different greenhouse gas concentration scenarios. For the evaluation of the heat stress risk, we considered the number and duration of heat stress events. Based on the changes in the heat stress events, various economic and environmental impacts were estimated. The impacts of the projected increase in heat stress risk varied among the barns due to different locations and designs as well as the anticipated climate change (considering different climate models and future greenhouse gas concentrations). There was an overall increasing trend in number and duration of heat stress events. At the end of the century, the number of annual stress events can be expected to increase by up to 2000, while the average duration of the events increases by up to 22 h compared to the end of the last century. This implies strong impacts on economics, environment and animal welfare and an urgent need for mid-term adaptation strategies. We anticipated that up to one-tenth of all hours of a year, correspondingly one-third of all days, will be classified as critical heat stress conditions. Due to heat stress, milk yield may decrease by about 2.8 % relative to the present European milk yield, and farmers may expect financial losses in the summer season of about 5.4 % of their monthly income. In addition, an increasing demand for emission reduction measures must be expected, as an emission increase of about 16 Gg of ammonia and 0.1 Gg of methane per year can be expected under the anticipated heat stress conditions. The cattle respiration rate increases by up to 60 %, and the standing time may be prolonged by 1 h. This causes health issues and increases the probability of medical treatments. The various impacts imply feedback loops in the climate system which are presently underexplored. Hence, future in-depth studies on the different impacts and adaptation options at different stress levels are highly recommended.

ACS Style

Sabrina Hempel; Christoph Menz; Severino Pinto; Elena Galán; David Janke; Fernando Estellés; Theresa Müschner-Siemens; Xiaoshuai Wang; Julia Heinicke; Guoqiang Zhang; Barbara Amon; Agustín del Prado; Thomas Amon. Heat stress risk in European dairy cattle husbandry under different climate change scenarios – uncertainties and potential impacts. Earth System Dynamics 2019, 10, 859 -884.

AMA Style

Sabrina Hempel, Christoph Menz, Severino Pinto, Elena Galán, David Janke, Fernando Estellés, Theresa Müschner-Siemens, Xiaoshuai Wang, Julia Heinicke, Guoqiang Zhang, Barbara Amon, Agustín del Prado, Thomas Amon. Heat stress risk in European dairy cattle husbandry under different climate change scenarios – uncertainties and potential impacts. Earth System Dynamics. 2019; 10 (4):859-884.

Chicago/Turabian Style

Sabrina Hempel; Christoph Menz; Severino Pinto; Elena Galán; David Janke; Fernando Estellés; Theresa Müschner-Siemens; Xiaoshuai Wang; Julia Heinicke; Guoqiang Zhang; Barbara Amon; Agustín del Prado; Thomas Amon. 2019. "Heat stress risk in European dairy cattle husbandry under different climate change scenarios – uncertainties and potential impacts." Earth System Dynamics 10, no. 4: 859-884.

Review article
Published: 08 November 2019 in Biosystems Engineering
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Currently the temperature humidity index (THI) is a common method of evaluating the risk of heat stress in cows by employing climatic parameters. However, the THI is a general and indirect indicator that fails to consider individual cows. Various studies have used animal-related parameters to account for the heat load of individual cows. This review provides an overview of different heat stress indicators that have been used in the past 10 years with a focus on animal-related and non-invasive indicators. These indicators are reviewed with regard to their potential for quantifying individual heat loads in ongoing and future studies of dairy cows. The review is divided into sections covering physiological, behavioural and performance indicators. Parameters that appear to be suitable for assessing the individual stress loads of dairy cows include respiration rate and body temperature, whereas losses in milk yield are more a consequence of heat stress than an indicator. Using activity and feeding behaviour as an indicator of heat stress may depend on the cows' physiological state. However, no thresholds for animal-related indicators employed as signs of heat load can be found in the literature. In contrast, thresholds for THI levels are described above which changes in cows’ physiology and behaviour are detectable under heat stress. In conclusion, the development and use of non-invasive sensors should focus on physiological indicators, and further studies are needed to determine the thresholds for these indicators.

ACS Style

Gundula Hoffmann; Piotr Herbut; Severino Pinto; Julia Heinicke; Björn Kuhla; Thomas Amon. Animal-related, non-invasive indicators for determining heat stress in dairy cows. Biosystems Engineering 2019, 199, 83 -96.

AMA Style

Gundula Hoffmann, Piotr Herbut, Severino Pinto, Julia Heinicke, Björn Kuhla, Thomas Amon. Animal-related, non-invasive indicators for determining heat stress in dairy cows. Biosystems Engineering. 2019; 199 ():83-96.

Chicago/Turabian Style

Gundula Hoffmann; Piotr Herbut; Severino Pinto; Julia Heinicke; Björn Kuhla; Thomas Amon. 2019. "Animal-related, non-invasive indicators for determining heat stress in dairy cows." Biosystems Engineering 199, no. : 83-96.