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T S Barnes - One of the best experts on this subject based on the ideXlab platform.
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Associations between Feedlot management practices and bovine respiratory disease in Australian Feedlot cattle
Preventive veterinary medicine, 2016Co-Authors: K.e. Hay, Timothy J Mahony, Archie C A Clements, John Morton, T S BarnesAbstract:Bovine respiratory disease (BRD) is the major cause of clinical disease and death in Feedlot cattle. A prospective longitudinal study was conducted in a population of Australian Feedlot cattle to assess associations between factors related to Feedlot management and risk of BRD. In total, 35,131 animals in 170 pens (cohorts) inducted into 14 Feedlots were included in statistical analyses. Causal diagrams were used to inform model building to allow separate estimation of total and direct effects. Multilevel mixed effects logistic regression models were fitted within the Bayesian framework. The placement of pen water troughs such that they could be accessed by animals in adjoining pens was associated with markedly increased risk of BRD (OR 4.3, 95% credible interval: 1.4-10.3). Adding animals to pens over multiple days was associated with increased risk of BRD across all animals in those pens compared to placing all animals in the pen on a single day (total effect: OR 1.9, 95% credible interval: 1.2-2.8). The much attenuated direct effect indicated that this was primarily mediated via factors on indirect pathways so it may be possible to ameliorate the adverse effects of adding animals to pens over multiple days by altering exposure to these intervening factors (e.g. mixing history). In pens in which animals were added to the pen over multiple days, animals added ≥7 days (OR: 0.7, credible interval: 0.5-0.9) or 1-6 days (OR: 0.8, credible interval: 0.7-1.0) before the last animal was added were at modestly reduced risk of BRD compared to the animals that were added to the pen on the latest day. Further research is required to disentangle effects of cohort formation patterns at animal-level and higher levels on animal-level risk of BRD. Vaccination against Bovine herpesvirus 1 at Feedlot entry was investigated but results were inconclusive and further research is required to evaluate vaccine efficacy. We conclude that there are practical interventions available to Feedlot managers to reduce the risk of cattle developing BRD at the Feedlot. We recommend placement of water troughs in Feedlot pens so that they cannot be accessed by animals in adjoining pens. Further research is required to identify practical and cost-effective management strategies that allow longer adaption times for cattle identified prior to induction as being at higher risk of developing BRD.
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associations between animal characteristic and environmental risk factors and bovine respiratory disease in australian Feedlot cattle
Preventive Veterinary Medicine, 2016Co-Authors: J M Morton, Timothy J Mahony, Archie C A Clements, T S BarnesAbstract:A prospective longitudinal study was conducted in a population of Australian Feedlot cattle to assess associations between animal characteristic and environmental risk factors and risk of bovine respiratory disease (BRD). Animal characteristics were recorded at induction, when animals were individually identified and enrolled into study cohorts (comprising animals in a Feedlot pen). Environmental risk factors included the year and season of induction, source region and Feedlot region and summary variables describing weather during the first week of follow-up. In total, 35,131 animals inducted into 170 cohorts within 14 Feedlots were included in statistical analyses. Causal diagrams were used to inform model building and multilevel mixed effects logistic regression models were fitted within the Bayesian framework. Breed, induction weight and season of induction were significantly and strongly associated with risk of BRD. Compared to Angus cattle, Herefords were at markedly increased risk (OR: 2.0, 95% credible interval: 1.5–2.6) and tropically adapted breeds and their crosses were at markedly reduced risk (OR: 0.5, 95% credible interval: 0.3–0.7) of developing BRD. Risk of BRD declined with increased induction weight, with cattle in the heaviest weight category (≥480 kg) at moderately reduced risk compared to cattle weighing <400 kg at induction (OR: 0.6, 95% credible interval: 0.5–0.7). Animals inducted into Feedlots during summer (OR: 2.4, 95% credible interval: 1.4–3.8) and autumn (OR: 2.1, 95% credible interval: 1.2–3.2) were at markedly increased risk compared to animals inducted during spring. Knowledge of these risk factors may be useful in predicting BRD risk for incoming groups of cattle in Australian Feedlots. This would then provide the opportunity for Feedlot managers to tailor management strategies for specific subsets of animals according to predicted BRD risk.
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risk factors for bovine respiratory disease in australian Feedlot cattle use of a causal diagram informed approach to estimate effects of animal mixing and movements before Feedlot entry
Preventive Veterinary Medicine, 2014Co-Authors: T S Barnes, J M Morton, Archie C A Clements, Timothy J MahonyAbstract:A nationwide longitudinal study was conducted to investigate risk factors for bovine respiratory disease (BRD) in cattle in Australian Feedlots. After induction (processing), cattle were placed in Feedlot pens (cohorts) and monitored for occurrence of BRD over the first 50 days on feed. Data from a national cattle movement database were used to derive variables describing mixing of animals with cattle from other farms, numbers of animals in groups before arrival at the Feedlot, exposure of animals to saleyards before arrival at the Feedlot, and the timing and duration of the animal's move to the vicinity of the Feedlot. Total and direct effects for each risk factor were estimated using a causal diagram-informed process to determine covariates to include in four-level Bayesian logistic regression models. Mixing, group size and timing of the animal's move to the Feedlot were important predictors of BRD. Animals not mixed with cattle from other farms prior to 12 days before induction and then exposed to a high level of mixing (≥4 groups of animals mixed) had the highest risk of developing BRD (OR 3.7) compared to animals mixed at least 4 weeks before induction with less than 4 groups forming the cohort. Animals in groups formed at least 13 days before induction comprising 100 or more (OR 0.5) or 50-99 (OR 0.8) were at reduced risk compared to those in groups of less than 50 cattle. Animals moved to the vicinity of the Feedlot at least 27 days before induction were at reduced risk (OR 0.4) compared to cattle undergoing short-haul transportation (<6. h) to the Feedlot within a day of induction, while those experiencing longer transportation durations (6. h or more) within a day of induction were at slightly increased risk (OR 1.2). Knowledge of these risk factors could potentially be used to inform management decisions to reduce the risk of BRD in Feedlot cattle.
Timothy J Mahony - One of the best experts on this subject based on the ideXlab platform.
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Associations between Feedlot management practices and bovine respiratory disease in Australian Feedlot cattle
Preventive veterinary medicine, 2016Co-Authors: K.e. Hay, Timothy J Mahony, Archie C A Clements, John Morton, T S BarnesAbstract:Bovine respiratory disease (BRD) is the major cause of clinical disease and death in Feedlot cattle. A prospective longitudinal study was conducted in a population of Australian Feedlot cattle to assess associations between factors related to Feedlot management and risk of BRD. In total, 35,131 animals in 170 pens (cohorts) inducted into 14 Feedlots were included in statistical analyses. Causal diagrams were used to inform model building to allow separate estimation of total and direct effects. Multilevel mixed effects logistic regression models were fitted within the Bayesian framework. The placement of pen water troughs such that they could be accessed by animals in adjoining pens was associated with markedly increased risk of BRD (OR 4.3, 95% credible interval: 1.4-10.3). Adding animals to pens over multiple days was associated with increased risk of BRD across all animals in those pens compared to placing all animals in the pen on a single day (total effect: OR 1.9, 95% credible interval: 1.2-2.8). The much attenuated direct effect indicated that this was primarily mediated via factors on indirect pathways so it may be possible to ameliorate the adverse effects of adding animals to pens over multiple days by altering exposure to these intervening factors (e.g. mixing history). In pens in which animals were added to the pen over multiple days, animals added ≥7 days (OR: 0.7, credible interval: 0.5-0.9) or 1-6 days (OR: 0.8, credible interval: 0.7-1.0) before the last animal was added were at modestly reduced risk of BRD compared to the animals that were added to the pen on the latest day. Further research is required to disentangle effects of cohort formation patterns at animal-level and higher levels on animal-level risk of BRD. Vaccination against Bovine herpesvirus 1 at Feedlot entry was investigated but results were inconclusive and further research is required to evaluate vaccine efficacy. We conclude that there are practical interventions available to Feedlot managers to reduce the risk of cattle developing BRD at the Feedlot. We recommend placement of water troughs in Feedlot pens so that they cannot be accessed by animals in adjoining pens. Further research is required to identify practical and cost-effective management strategies that allow longer adaption times for cattle identified prior to induction as being at higher risk of developing BRD.
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associations between animal characteristic and environmental risk factors and bovine respiratory disease in australian Feedlot cattle
Preventive Veterinary Medicine, 2016Co-Authors: J M Morton, Timothy J Mahony, Archie C A Clements, T S BarnesAbstract:A prospective longitudinal study was conducted in a population of Australian Feedlot cattle to assess associations between animal characteristic and environmental risk factors and risk of bovine respiratory disease (BRD). Animal characteristics were recorded at induction, when animals were individually identified and enrolled into study cohorts (comprising animals in a Feedlot pen). Environmental risk factors included the year and season of induction, source region and Feedlot region and summary variables describing weather during the first week of follow-up. In total, 35,131 animals inducted into 170 cohorts within 14 Feedlots were included in statistical analyses. Causal diagrams were used to inform model building and multilevel mixed effects logistic regression models were fitted within the Bayesian framework. Breed, induction weight and season of induction were significantly and strongly associated with risk of BRD. Compared to Angus cattle, Herefords were at markedly increased risk (OR: 2.0, 95% credible interval: 1.5–2.6) and tropically adapted breeds and their crosses were at markedly reduced risk (OR: 0.5, 95% credible interval: 0.3–0.7) of developing BRD. Risk of BRD declined with increased induction weight, with cattle in the heaviest weight category (≥480 kg) at moderately reduced risk compared to cattle weighing <400 kg at induction (OR: 0.6, 95% credible interval: 0.5–0.7). Animals inducted into Feedlots during summer (OR: 2.4, 95% credible interval: 1.4–3.8) and autumn (OR: 2.1, 95% credible interval: 1.2–3.2) were at markedly increased risk compared to animals inducted during spring. Knowledge of these risk factors may be useful in predicting BRD risk for incoming groups of cattle in Australian Feedlots. This would then provide the opportunity for Feedlot managers to tailor management strategies for specific subsets of animals according to predicted BRD risk.
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evaluation of an igg enzyme linked immunosorbent assay as a serological assay for detection of mycoplasma bovis infection in Feedlot cattle
Journal of Clinical Microbiology, 2016Co-Authors: Nadeeka K Wawegama, Timothy J Mahony, Philip F Markham, Anna Kanci, M L Schibrowski, Sally Oswin, T S Barnes, Simon M Firestone, Glenn F BrowningAbstract:Mycoplasma bovis is a pathogen of emerging significance in cattle throughout the world that is causing a range of diseases, including mastitis, arthritis, and pneumonia. The limited availability and efficacy of current diagnostic and prophylactic tools for its control and its increasing antimicrobial resistance are contributing to its increasing importance in beef and dairy cattle. We have developed an indirect IgG enzyme-linked immunosorbent assay (ELISA) based on a recombinant fragment of the MilA protein and have shown its potential as an effective diagnostic tool. To more comprehensively estimate the diagnostic sensitivity and specificity of this IgG ELISA for detection of infection with M. bovis in cattle and to define a suitable cutoff for use in the field, we further assessed its performance in experimentally infected calves in a closed beef herd and by applying Bayesian latent class modeling to laboratory testing results from 7,448 cattle entering Australian Feedlots. The most effective cutoff points were estimated to be 68.6 antibody units (AU) for experimentally infected calves and to be 58.7 AU for a closed adult herd. Under field conditions, in Feedlot cattle the globally optimal cutoff was estimated to be 105 AU. At this cutoff, the diagnostic sensitivity was 94.3% (95% probability interval [PI], 89.9% to 99.6%) with a diagnostic specificity of 94.4% (95% PI, 90.3% to 99.6%). Applying this 105 AU cutoff, 13.1% of cattle were seropositive for infection with M. bovis on entry into Feedlots, and 73.5% were seropositive when followed up approximately 6 weeks later suggesting a high risk of infection shortly after entry into Feedlots.
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risk factors for bovine respiratory disease in australian Feedlot cattle use of a causal diagram informed approach to estimate effects of animal mixing and movements before Feedlot entry
Preventive Veterinary Medicine, 2014Co-Authors: T S Barnes, J M Morton, Archie C A Clements, Timothy J MahonyAbstract:A nationwide longitudinal study was conducted to investigate risk factors for bovine respiratory disease (BRD) in cattle in Australian Feedlots. After induction (processing), cattle were placed in Feedlot pens (cohorts) and monitored for occurrence of BRD over the first 50 days on feed. Data from a national cattle movement database were used to derive variables describing mixing of animals with cattle from other farms, numbers of animals in groups before arrival at the Feedlot, exposure of animals to saleyards before arrival at the Feedlot, and the timing and duration of the animal's move to the vicinity of the Feedlot. Total and direct effects for each risk factor were estimated using a causal diagram-informed process to determine covariates to include in four-level Bayesian logistic regression models. Mixing, group size and timing of the animal's move to the Feedlot were important predictors of BRD. Animals not mixed with cattle from other farms prior to 12 days before induction and then exposed to a high level of mixing (≥4 groups of animals mixed) had the highest risk of developing BRD (OR 3.7) compared to animals mixed at least 4 weeks before induction with less than 4 groups forming the cohort. Animals in groups formed at least 13 days before induction comprising 100 or more (OR 0.5) or 50-99 (OR 0.8) were at reduced risk compared to those in groups of less than 50 cattle. Animals moved to the vicinity of the Feedlot at least 27 days before induction were at reduced risk (OR 0.4) compared to cattle undergoing short-haul transportation (<6. h) to the Feedlot within a day of induction, while those experiencing longer transportation durations (6. h or more) within a day of induction were at slightly increased risk (OR 1.2). Knowledge of these risk factors could potentially be used to inform management decisions to reduce the risk of BRD in Feedlot cattle.
Andredenis G Wright - One of the best experts on this subject based on the ideXlab platform.
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microorganisms in the rumen and reticulum of buffalo bubalus bubalis fed two different feeding systems
BMC Research Notes, 2016Co-Authors: Raul Franzolin, Andredenis G WrightAbstract:The community of microorganisms in the rumen and reticulum is influenced by feeding as well as the species and geographical distribution of ruminant animals. Bacteria, methanogenic archaea and ciliate protozoa existing in the rumen and reticulum were evaluated by real-time polymerase chain reaction and light microscopy in buffalo in two feeding systems, grazing and Feedlot. No significant differences were observed in the total concentrations of bacteria/mL and archaea between rumen and reticulum, and between pasture and Feedlots, or interactions between variables. However, the largest density of bacteria and smallest density of archaea was observed in the rumen of grazing animals. The total ciliates protozoa community was higher in grazing buffalo than those in the Feedlot on a concentrated diet. There were significant interactions between location in the gastrointestinal tract (rumen vs reticulum) and types of diets (grazing vs Feedlot) in the composition of ciliates. Our data showed differences in the microbial community of the rumen and reticulum between grazing and Feedlot feeding systems demonstrating relevant changes in the microorganism:host relationship existing on rumen–reticulum ecosystem.
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Microorganisms in the rumen and reticulum of buffalo (Bubalus bubalis) fed two different feeding systems
BMC Research Notes, 2016Co-Authors: Raul Franzolin, Andredenis G WrightAbstract:Background The community of microorganisms in the rumen and reticulum is influenced by feeding as well as the species and geographical distribution of ruminant animals. Bacteria, methanogenic archaea and ciliate protozoa existing in the rumen and reticulum were evaluated by real-time polymerase chain reaction and light microscopy in buffalo in two feeding systems, grazing and Feedlot. Results No significant differences were observed in the total concentrations of bacteria/mL and archaea between rumen and reticulum, and between pasture and Feedlots, or interactions between variables. However, the largest density of bacteria and smallest density of archaea was observed in the rumen of grazing animals. The total ciliates protozoa community was higher in grazing buffalo than those in the Feedlot on a concentrated diet. There were significant interactions between location in the gastrointestinal tract (rumen vs reticulum) and types of diets (grazing vs Feedlot) in the composition of ciliates. Conclusions Our data showed differences in the microbial community of the rumen and reticulum between grazing and Feedlot feeding systems demonstrating relevant changes in the microorganism:host relationship existing on rumen–reticulum ecosystem.
Archie C A Clements - One of the best experts on this subject based on the ideXlab platform.
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Associations between Feedlot management practices and bovine respiratory disease in Australian Feedlot cattle
Preventive veterinary medicine, 2016Co-Authors: K.e. Hay, Timothy J Mahony, Archie C A Clements, John Morton, T S BarnesAbstract:Bovine respiratory disease (BRD) is the major cause of clinical disease and death in Feedlot cattle. A prospective longitudinal study was conducted in a population of Australian Feedlot cattle to assess associations between factors related to Feedlot management and risk of BRD. In total, 35,131 animals in 170 pens (cohorts) inducted into 14 Feedlots were included in statistical analyses. Causal diagrams were used to inform model building to allow separate estimation of total and direct effects. Multilevel mixed effects logistic regression models were fitted within the Bayesian framework. The placement of pen water troughs such that they could be accessed by animals in adjoining pens was associated with markedly increased risk of BRD (OR 4.3, 95% credible interval: 1.4-10.3). Adding animals to pens over multiple days was associated with increased risk of BRD across all animals in those pens compared to placing all animals in the pen on a single day (total effect: OR 1.9, 95% credible interval: 1.2-2.8). The much attenuated direct effect indicated that this was primarily mediated via factors on indirect pathways so it may be possible to ameliorate the adverse effects of adding animals to pens over multiple days by altering exposure to these intervening factors (e.g. mixing history). In pens in which animals were added to the pen over multiple days, animals added ≥7 days (OR: 0.7, credible interval: 0.5-0.9) or 1-6 days (OR: 0.8, credible interval: 0.7-1.0) before the last animal was added were at modestly reduced risk of BRD compared to the animals that were added to the pen on the latest day. Further research is required to disentangle effects of cohort formation patterns at animal-level and higher levels on animal-level risk of BRD. Vaccination against Bovine herpesvirus 1 at Feedlot entry was investigated but results were inconclusive and further research is required to evaluate vaccine efficacy. We conclude that there are practical interventions available to Feedlot managers to reduce the risk of cattle developing BRD at the Feedlot. We recommend placement of water troughs in Feedlot pens so that they cannot be accessed by animals in adjoining pens. Further research is required to identify practical and cost-effective management strategies that allow longer adaption times for cattle identified prior to induction as being at higher risk of developing BRD.
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associations between animal characteristic and environmental risk factors and bovine respiratory disease in australian Feedlot cattle
Preventive Veterinary Medicine, 2016Co-Authors: J M Morton, Timothy J Mahony, Archie C A Clements, T S BarnesAbstract:A prospective longitudinal study was conducted in a population of Australian Feedlot cattle to assess associations between animal characteristic and environmental risk factors and risk of bovine respiratory disease (BRD). Animal characteristics were recorded at induction, when animals were individually identified and enrolled into study cohorts (comprising animals in a Feedlot pen). Environmental risk factors included the year and season of induction, source region and Feedlot region and summary variables describing weather during the first week of follow-up. In total, 35,131 animals inducted into 170 cohorts within 14 Feedlots were included in statistical analyses. Causal diagrams were used to inform model building and multilevel mixed effects logistic regression models were fitted within the Bayesian framework. Breed, induction weight and season of induction were significantly and strongly associated with risk of BRD. Compared to Angus cattle, Herefords were at markedly increased risk (OR: 2.0, 95% credible interval: 1.5–2.6) and tropically adapted breeds and their crosses were at markedly reduced risk (OR: 0.5, 95% credible interval: 0.3–0.7) of developing BRD. Risk of BRD declined with increased induction weight, with cattle in the heaviest weight category (≥480 kg) at moderately reduced risk compared to cattle weighing <400 kg at induction (OR: 0.6, 95% credible interval: 0.5–0.7). Animals inducted into Feedlots during summer (OR: 2.4, 95% credible interval: 1.4–3.8) and autumn (OR: 2.1, 95% credible interval: 1.2–3.2) were at markedly increased risk compared to animals inducted during spring. Knowledge of these risk factors may be useful in predicting BRD risk for incoming groups of cattle in Australian Feedlots. This would then provide the opportunity for Feedlot managers to tailor management strategies for specific subsets of animals according to predicted BRD risk.
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risk factors for bovine respiratory disease in australian Feedlot cattle use of a causal diagram informed approach to estimate effects of animal mixing and movements before Feedlot entry
Preventive Veterinary Medicine, 2014Co-Authors: T S Barnes, J M Morton, Archie C A Clements, Timothy J MahonyAbstract:A nationwide longitudinal study was conducted to investigate risk factors for bovine respiratory disease (BRD) in cattle in Australian Feedlots. After induction (processing), cattle were placed in Feedlot pens (cohorts) and monitored for occurrence of BRD over the first 50 days on feed. Data from a national cattle movement database were used to derive variables describing mixing of animals with cattle from other farms, numbers of animals in groups before arrival at the Feedlot, exposure of animals to saleyards before arrival at the Feedlot, and the timing and duration of the animal's move to the vicinity of the Feedlot. Total and direct effects for each risk factor were estimated using a causal diagram-informed process to determine covariates to include in four-level Bayesian logistic regression models. Mixing, group size and timing of the animal's move to the Feedlot were important predictors of BRD. Animals not mixed with cattle from other farms prior to 12 days before induction and then exposed to a high level of mixing (≥4 groups of animals mixed) had the highest risk of developing BRD (OR 3.7) compared to animals mixed at least 4 weeks before induction with less than 4 groups forming the cohort. Animals in groups formed at least 13 days before induction comprising 100 or more (OR 0.5) or 50-99 (OR 0.8) were at reduced risk compared to those in groups of less than 50 cattle. Animals moved to the vicinity of the Feedlot at least 27 days before induction were at reduced risk (OR 0.4) compared to cattle undergoing short-haul transportation (<6. h) to the Feedlot within a day of induction, while those experiencing longer transportation durations (6. h or more) within a day of induction were at slightly increased risk (OR 1.2). Knowledge of these risk factors could potentially be used to inform management decisions to reduce the risk of BRD in Feedlot cattle.
Thomas K. Flesch - One of the best experts on this subject based on the ideXlab platform.
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Ammonia and greenhouse gas emissions at beef cattle Feedlots in Alberta Canada
Agricultural and Forest Meteorology, 2018Co-Authors: Sean M. Mcginn, Thomas K. FleschAbstract:Abstract This study was conducted at beef cattle Feedlots, over two years in southern Alberta Canada, and focused on deriving the ammonia, methane, nitrous oxide and carbon dioxide emissions from two Feedlots from June/July to October. Line-averaging sensors were used to measure ambient gas concentrations in the vicinity of the Feedlots, and an inverse dispersion method was used to calculate emissions. Results show that ammonia and methane emissions were consistent with that measured from other studies. Both Feedlots lost about 40% of the nitrogen feed intake as ammonia. The emission of nitrous oxide, when compared on a greenhouse gas bases, was similar to the methane emission. A diet difference between Feedlots coincided with a slight difference in Feedlot methane emission. There was good agreement between previously reported ammonia and methane emission rates and those derived in our Feedlot study. Further evaluation of the underlying relationships causing variation in emissions should follow. A key to understanding emissions at commercial Feedlots is to fully engage the management data available.
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A Snapshot of Greenhouse Gas Emissions from a Cattle Feedlot.
Journal of environmental quality, 2015Co-Authors: Mei Bai, Sean M. Mcginn, Thomas K. Flesch, Deli ChenAbstract:Beef cattle Feedlots emit large amounts of the greenhouse gases (GHG) methane (CH) and nitrous oxide (NO), as well as ammonia (NH), which contributes to NO emission when NH is deposited to land. However, there is a lack of simultaneous, in situ, and nondisturbed measurements of the major GHG gas components from beef cattle Feedlots, or measurements from different Feedlot sources. A short-term campaign at a beef cattle Feedlot in Victoria, Australia, quantified CH, NO, and NH emissions from the Feedlot pens, manure stockpiles, and surface run-off pond. Open-path Fourier transform infrared (OP-FTIR) spectrometers and open-path lasers (OP-Laser) were used with an inverse-dispersion technique to estimate emissions. Daily average emissions of CH, NO, and NH were 132 (± 2.3 SE), 0, and 117 (± 4.5 SE) g animal d from the pens and 22 (± 0.7 SE), 2 (± 0.2 SE), and 9 (± 0.6 SE) g animal d from the manure stockpiles. Emissions of CH and NH from the run-off pond were less than 0.5 g animal d. Extrapolating these results to the Feedlot population of cattle across Australia would mean that Feedlots contribute approximately 2% of the agricultural GHG emissions and 2.7% of livestock sector emissions, lower than a previous estimate of 3.5%.
