Cattle Feedyards Research Articles

Identifying Safety Training Resource Needs in the Cattle Feeding Industry in the Midwestern United States

Cattle feedyards are a high-risk environment. They are characterized by high rates of occupational injuries and illnesses. As such, there is a clear need to address the health and safety of cattle feedyard workers. Therefore, the purpose of this cross-sectional study was to explore safety training practices and preferences in the cattle feeding industry. A survey of feedyard managers, feedyard safety trainers, and feedyard operators was conducted (n = 28). We found that only half of respondents had dedicated safety personnel; however, there was interest in a safety training program, conducted through short hands-on and in-person methods with materials available in English and Spanish. The majority of participants were also interested in a feedyard safety certification program. Participants reaffirmed the importance of partnering with industry and other stakeholders when conducting these types of programs. The results of this Phase 1-type translational research study will be used to guide the development of feedyard safety trainings and a corresponding recognition program for feedyards and feedyard workers as part of the “Improving Safety and Health of Cattle Feedyard Workers” project.

Evaluation of the Texas Feed Yard Workforce: Survey of Stockperson Attitudes and Perceptions towards Euthanasia, Animal Care and Employee Value

A survey was administered to Texas cattle feedyard employees (n =111) from 31 different operations measuring stockperson perception, job satisfaction and socioeconomic status using Likert statements and multiple-choice questions. Differences among employment roles (manager, pen rider, processor (those who vaccinate and implant incoming calves), doctor (non-veterinarians)) were evaluated using a Kruskal-Wallis test followed by a Multiple Comparison procedure. Managers strongly agreed with the statement “beef cattle are not dirty” more than doctors (P = 0.03) and that “cattle behavior is affected by the way we treat them” than pen riders (P = 0.002) or processors (P = 0.01). Managers were less likely than doctors, pen riders and processors to believe they have too many cattle to look after (P = 0.05, P = 0.006 and P = 0.01, respectively). Pen riders reported less confidence in performing euthanasia than doctors (P = 0.02) and managers (P = 0.02) and, along with processors, agreed that cattle were not always euthanized in a timely manner (P = 0.02 and P = 0.02, respectively). While all roles viewed Holstein cattle unfavorably (P < 0.001), processors viewed them more positively than pen riders (P = 0.05) and managers (P = 0.001). Socioeconomic results showed that Texas feedyards have a dedicated, passionate work force, with 43% of participants having worked in the industry for 9+ years and 49% of participants working at cattle feedyards because they enjoy working with animals. Unfortunately, it was evident that stock people are underpaid (57% of participants making between $10-15/hr) and overworked (76% of participants working 50+ hrs/week). Survey responses identified critical role-dependent knowledge gaps and biases. A disconnect was observed among compensation, workload and the duration of time stock people spend interacting with cattle. Increasing industry investment in feedyard employees and providing breed-specific and employee role-specific education may promote an encouraging workplace that ensures feedlot cattle experience good welfare.

A preliminary evaluation of veterinary antibiotics, estrogens, in vitro estrogenic activity and microbial communities in airborne particulate matter collected near dairy production facilities

Particulate matter (PM) emitted from beef cattle feedyards transports manure-affiliated compounds including antibiotics and steroids from feedyards into the surrounding environment. Similarly, commercial dairy operations have the potential to release PM, comprised largely of aerosolized manure, into the surrounding environment along with associated veterinary antibiotics and steroids. The goal of this study was to quantify and compare total suspended particulates, antibiotics and estrogens collected upwind and downwind of dairies in the Southern High Plains, and to characterize microbial community structure and in vitro estrogenic activity of collected PM. PM collected downwind of dairies had greater microbial diversity (as measured by number of operational taxonomic units) and had greater frequencies of detection for antibiotics and estrogens than associated upwind PM. Dominant bacterial phyla and overall microbial community composition were similar among upwind and downwind PM, and extracts of upwind and downwind PM produced no in vitro estrogenic activity. Although this study surveyed a limited number of dairies in the region, these results suggest that dairy operations in the Southern High Plains, in contrast to feedyards, appear to be minor contributors of total aerial PM and associated antibiotics and steroids to the terrestrial environment.

Nitrous Oxide Emissions from an Open-Lot Beef Cattle Feedyard in Texas

Abstract. Nitrous oxide (N2O) is a greenhouse gas (GHG) with a global warming potential much greater than that of carbon dioxide (CO2). Nitrous oxide is emitted from the manure-covered pen surfaces of open-lot beef cattle feedyards, and more than six million beef cattle are fed in the Southern Great Plains. A field research project was conducted to determine the temporal and spatial variability of N2O emissions from the pen surfaces of a commercial feedyard before and after simulated rainfall. Two week-long monitoring cycles were conducted in April and August 2018 in the Texas Panhandle. Temporal variability was assessed using six continuous automated flux chambers per pen, and spatial variability was assessed using a portable chamber at up to 61 locations in a single pen. Diurnal fluxes varied 5-fold to 10-fold over a 24 h period. Flux varied seasonally, with arithmetic means of 0.56 mg N2O-N m-2 h-1 in April and 3.21 mg N2O-N m-2 h-1 in August. Fluxes measured spatially across the pen surface over a 2 h period at midday were lognormally distributed, with April geometric and arithmetic means of -0.81 and 0.80 mg N2O-N m-2 h-1, respectively, and August geometric and arithmetic means of 0.095 and 2.6 mg N2O-N m-2 h-1, respectively. Fluxes peaked shortly after simulated rainfall. Arithmetic mean N2O-N flux for the 2 d after rainfall increased over the background level by 4.6-fold in April and 1.7-fold in August. Manure properties measured at the time of flux measurement were poorly correlated with N2O emissions and were of little value for predicting N2O emissions, which confirmed that further work is warranted on the biochemistry of feedyard manure. The results of this field research will help refine models for predicting N2O emissions from open-lot beef cattle feedyards and help to develop effective mitigation methods to conserve feedyard N. Keywords: Beef cattle, Flux chamber, Greenhouse gas, Manure, Nitrous oxide, Rainfall.

Persistence of elevated concentrations of PM, affiliated pharmaceuticals, and tetracycline resistance genes downwind of feedyards

Beef cattle feedyards have been identified as sources of large amounts of particulate matter (PM) which may transport affiliated chemicals including steroids, beta agonists, and antibiotics from feedyards into the environment. This study is the first to examine persistence of PM-affiliated pharmaceuticals downwind of feedyards using multiple downwind samples collected at increasing distances from feedyard boundaries (n = 5). Concentrations of antibiotics and ractopamine per gram of PM remained consistent at all downwind locations (out to 4.8 km) whereas concentrations per m3 air decreased significantly at distances between 0.1 and 0.7 km downwind, corresponding to significant decreases in mass of PM. Monensin was present in the highest concentrations of any measured pharmaceutical, with concentrations of 37 μg/g PM (376 ng/m3) air in samples collected within 0.1 km downwind of feedyards. Total copy count of tetracycline resistance genes (tetW, tetQ, tetO, tetM, tetL, and tetB) were also significantly increased in samples collected within 0.1 km downwind of feedyards (106 copies) as compared to samples collected upwind (103 copies) and farther downwind (104 copies) of feedyard boundaries. These results suggest that transport of pharmaceutical-laden PM into the terrestrial environment is occurring primarily via PM deposition within 0.7 km of the feedyard, while aerial transport persists over longer distances (>4.8 km).

Genesis of Antibiotic Resistance (AR) XXXIV: Effective implementation of preventive measures in Feed Lot/Feed Yard or Caged Animal Feeding Operations (CAFO's) mitigate particulate matter (PM) induced AR pandemic (ARP)

PM originating from large‐scale beef cattle feed yards was shown to spread antibiotics, antibiotic resistance genes (ARG) to tetracycline, and ruminant‐associated microbes (EHP. 2015:123:337–343). To acquire firsthand information on the industrial practice of implementing preventive measures to minimize or avoid the PM, we have undertaken an in‐depth field survey at a Feed yard Z, (Name withheld), Quemado, Texas. 16,000 cattle reside in feedlot, which is obtained mainly from Mexico and around the area. Upon arrival, cattle were first weighed and put into pins for about ten days by the cowboys. Cattle housing is calculated based on 1 cattle for every 10 acres. Prophylactic medication was administered and observed for a period of time prior to releasing into the home pin. Cattle are fed a mixture of molasses, corn, proteins, and hay. The cattle are checked for their well being every single day during the early morning and evening by the cowboys at the feedlot. The United States Department of Agriculture (USDA) appointed a veterinarian to monitor the feeding regimen, health, and overall sanitary conditions of the feed yard on a regular basis and to document it. We have observed that animals grazing pattern were in accordance with the stipulations presented during the review. Though the antibiotics such as monensin and tetracycline antibiotics used in feed yards on a regular basis, our inquiry determined that is not the case. Formation of PM is a complex reaction resulting from the reactions of sulfur dioxide, nitrogen oxides, and other organic matters such as antibiotics. The United States Environmental Protection Agency defines the PM sizes, as PM10 (inhalable particles, with diameters that are generally 10 micrometers and smaller); and PM2.5 (fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller). As per the National Weather Service, on an average, the wind flow speed pattern in this location is Wind ESE 9 MPH, Visibility 7 mi, and barometer 30.15 inches. Formation and transport of PM are dependent on temperature inversion, frontal activities (wind velocities subjected to surface and atmospheric turbulence), differential distribution in downwind (carry more PM – density dependent) vs. upwind, geographical point, and finally the dynamic flex of atmospheric moisture with reference to the altitude. Though, our effort to obtain epidemiological data on PM induced spread infectious diseases compared to the regions devoid of feedlots in Texas were unsuccessful, we were able to discern that the biggest risk factor in raising the cattle in the big housing pins are the flies and the organic wastes generated especially during the summer. Effective measures as Biological Integrated Insect Control (BIIC) programs as a part of Integrated Pest Management (IPM) programs are implemented as per the need. Upon identification, sick cattle are isolated and housed in hospital pens that are managed by cowboys who are highly trained. We have been advised that multitude of agencies such as Texas Commission on Environmental Quality, Texas Water Development Board, TCEQ and USEPA are involved in monitoring the environment, animal welfare, and industry standards. Taken together, it is concluded that implementation of measures would possibly mitigate the PM induced ARP. However, aforesaid contributing factors for the formation of PM are a serious cause for concern in a mass CAFO such as Lubbock, Texas and Oklahoma and developing countries.Support or Funding InformationSupported by RISE ‐ high‐impact practices in the learning environment – SWTJC and professional development funds to Subburaj KannanThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Ractopamine in particulate matter emitted from beef cattle feedyards and playa wetlands in the Central Plains.

Beef cattle in the United States are routinely administered ractopamine, a β-adrenergic receptor agonist, to enhance growth. The present study is the first to quantify ractopamine in feedyard-emitted particulate matter and playa wetlands near feedyards. Ractopamine was present in 92% of particulate matter samples, 16% of playa sediment samples, and 3% of playa water samples, at maximum concentrations of 4.7 μg/g, 5.2 ng/g (dry wt), and 271 ng/L, respectively. These data suggest that aerial transmission and deposition of particulate matter is a transport mechanism for ractopamine between feedyards and aquatic systems in the region. Environ Toxicol Chem 2018;37:970-974. © 2017 SETAC.

Viable Antimicrobial Resistant Bacteria are Transported from Cattle Feed Yards via Aerosolized Particulate Matter

Copyright: © 2018 Smith PN, et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How Do Temperature and Rainfall Affect Nitrous Oxide Emissions from Open-Lot Beef Cattle Feedyard Pens?

Abstract. Temperature is a primary factor affecting greenhouse gas (GHG) emissions from agricultural soils, but little is known about how temperature affects nitrous oxide (N2O) emissions from manure. The majority of grain-fed cattle in the Texas Panhandle are finished in large, earthen-surfaced, open-lot feedyards. Manure accumulates in feedyard pens and creates an environment high in nitrogen (N) and carbon (C) that can lead to N2O losses. In previous studies, N2O-N emissions from feedyard manure have been highly variable, ranging from negligible amounts from dry manure to 200 mg m-2 h-1 after a simulated rainfall event. The objective of this research was to determine how temperature affects N2O emissions from feedyard manure following rainfall. A recirculating flow-through, non-steady-state (RFT-NSS) chamber system with 1 m2 pans was used to monitor N2O emissions from beef cattle manure following a single 25.4 mm simulated rainfall event. Emissions were monitored at manure temperatures of 5.0°C, 11.2°C, 17.2°C, 21.5°C, 26.8°C, 31.0°C, 38.1°C, and 46.2°C. At all temperatures, a single N2O episode was observed following rainfall, peaking 2 to 11 h after rainfall with duration of 2 to 3 d. A second N2O episode was observed at temperatures =31.0°C, peaking 3 to 4 d after rainfall with duration of 18 d. When present, the second N2O episode accounted for 72% to 83% of the 20 d cumulative emissions. A step-increase in cumulative N2O emissions was observed between 26.8°C and 31.0°C, believed to be due to a major shift from denitrification to nitrification as the primary process of N2O production. Empirical regression models were developed for predicting cumulative N2O emissions based on temperature, which showed 88% agreement between predicted and field-observed N2O-N flux rates. These regression models will be useful for further quantification of N2O emissions from open-lot beef cattle feedyards in the U.S. Southern High Plains and for assessment of practices for reducing GHG emissions. Keywords: Beef cattle, Chamber, Greenhouse gas, Manure, Nitrous oxide, Precipitation.

Transport mechanisms for veterinary pharmaceuticals from beef cattle feedyards to wetlands: Is aerial deposition a contributing source?

Veterinary pharmaceuticals from beef cattle feedyards have, with increasing frequency, been identified as contaminants in aquatic systems. Transport of these pharmaceuticals has generally been assumed to be via manure land application, surface runoff, or groundwater percolation. However, veterinary pharmaceuticals in airborne particulate matter downwind of beef cattle feedyards have recently been documented, indicating that aerial transport and deposition are a potential transport mechanism in arid and semi-arid environments. In this study, 35 hydrologically discrete playa wetlands within 15km of beef cattle feedyards were examined for occurrence of six steroid hormones and eight antibiotics. 17α-trenbolone, estrone, estradiol, tetracycline, chlortetracycline, oxytetracycline, tylosin, and monensin were all detected in either water or sediment samples. Concentrations for the majority of analytes were <15ng/g in sediment and <70ng/L in water. Tylosin and monensin were detected at highest concentrations in water, at 3 and 84μg/L, respectively. A correlation between distance from the nearest beef cattle feedyard and concentration of monensin in playa water was observed, similar to correlations observed between pharmaceutical concentrations and distance from feedyard among air samples collected downwind of feedyards. This study suggests that airborne transport and deposition of pharmaceutical-laden particulate matter are a possible contributor to pharmaceutical concentrations in aquatic systems. Aerial deposition of pharmaceutical-laden particulate matter, not typically included in risk assessments, is of yet poorly characterized but may play a significant role in pharmaceutical transport in arid and semi-arid locations and deserves further investigation.

Agrochemical Mixtures Detected on Wildflowers near Cattle Feed Yards

A variety of veterinary pharmaceuticals and pesticides are used on beef cattle feed yards to enhance growth and health of cattle and to control unwanted pests and parasites. Because growth promoters and antibiotics have recently been detected on particulate matter emanating from feed yards, we examined wildflowers collected near feed yards in the Southern Great Plains for the occurrence of antibiotics, β-agonists, other feed yard-related agrochemicals, and neonicotinoids used on regionally grown row crops. Wildflowers contained detectable concentrations of moxidectin, abamectin, monensin, ractopamine, and neonicotinoids (imidacloprid, thiamethoxam, and clothianidin). All wildflower samples contained at least one target analyte, while the majority (82%) contained multiple pharmaceuticals and/or pesticides, including 12% of wildflowers containing moxidectin, monensin, ractopamine, and a neonicotinoid. This preliminary survey demonstrates the potential for insect pollinators occurring near feed yards to beco...

Nitrous Oxide Emissions from Southern High Plains Beef Cattle Feedyards: Measurement and Modeling

Abstract. The Texas Panhandle produces approximately 42% of finished beef in the U.S., and cattle production is estimated to contribute 8 Tg carbon dioxide equivalents (CO2e) from nitrous oxide (N2O). Production of N2O in manure is largely a result of biochemical processes that are not static: N2O emission rates are dependent on numerous environmental and chemical factors. Process-based models that estimate N2O emissions from manure in open-lot cattle production systems typically rely on information derived from studies of soil biochemistry. Limited study has been conducted on manure-derived N2O in open-lot beef feedyards. The objectives of this study were to determine variables related to N2O losses from Texas Panhandle feedyards and develop empirical models to predict N2O emissions. Nitrous oxide flux data were collected from a series of 15 non-flow-through, non-steady-state (NFT-NSS) chamber studies (ten chambers per study) conducted from 2012 to 2014 on two commercial beef cattle feedyards. Manure samples (loose surface manure and the underlying manure pack) were analyzed for basic physicochemical properties, soluble carbon (C) and nitrogen (N), and ultraviolet-visible (UV-vis) spectral characteristics related to degree of organic matter (OM) stability and humification. Measured N2O emissions ranged from below detection to 101 mg m-2 h-1 (average 4.8 ±12 mg m-2 h-1) and were positively related to manure H2O content, temperature, and nitrate (NO3-) concentration (p &amp;lt; 0.01). Emissions were negatively related to manure OM, ammonia/ammonium (NH3/NH4+), dissolved C and dissolved N concentrations, and UV-vis parameters related to OM stability (p &amp;lt; 0.05). Based on these data, empirical models were developed and evaluated to predict manure-derived N2O emissions. Model predictions were not significantly different from observed N2O emissions (p &amp;lt; 0.05). The unbounded index of agreement (IA) indicated that model predictions were within 52% to 61% agreement with observations. Inclusion of OM characteristics improved model predictions of high (&amp;gt;30 mg m-2 h-1) N2O emissions but tended to overestimate low emission rates (&amp;lt;20 mg N2O m-2 h-1). This provides evidence for the importance of C stability in limiting manure N2O production. These models may improve parameterization of existing process-based models and are novel methods for predicting feedyard N2O emissions. Keywords: Beef cattle, Feedlot, Feedyard, Greenhouse gas, Manure, Modeling, Nitrous oxide, Organic matter, Urine, UV-vis spectroscopy.

Nitrous Oxide Emissions from Open-Lot Cattle Feedyards: A Review.

Nitrous oxide (NO) emissions from concentrated animal feeding operations, including cattle feedyards, have become an important research topic. However, there are limitations to current measurement techniques, uncertainty in the magnitude of feedyard NO fluxes, and a lack of effective mitigation methods. The objective of this review was to assess NO emission from cattle feedyards, including comparison of measured and modeled emission rates, discussion of measurement methods, and evaluation of mitigation options. Published annual per capita flux rates for beef cattle feedyards and open-lot dairies were highly variable and ranged from 0.002 to 4.3 kg NO animal yr. On an area basis, published emission rates ranged from 0 to 41 mg NO m h. From these studies and Intergovernmental Panel on Climate Change emission factors, calculated daily per capita NO fluxes averaged 18 ± 10 g NO animal d (range, 0.04-67 g NO animal d). This variation was due to inconsistency in measurement techniques as well as irregularity in NO production and emission attributable to management, animal diet, and environmental conditions. Based on this review, it is clear that the magnitude and dynamics of NO emissions from open-lot cattle systems are not well understood. Further research is required to quantify feedyard NO fluxes and develop cost-effective mitigation methods.

Occurrence and Characterization of Steroid Growth Promoters Associated with Particulate Matter Originating from Beef Cattle Feedyards.

Studies of steroid growth promoters from beef cattle feedyards have previously focused on effluent or surface runoff as the primary route of transport from animal feeding operations. There is potential for steroid transport via fugitive airborne particulate matter (PM) from cattle feedyards; therefore, the objective of this study was to characterize the occurrence and concentration of steroid growth promoters in PM from feedyards. Air sampling was conducted at commercial feedyards (n = 5) across the Southern Great Plains from 2010 to 2012. Total suspended particulates (TSP), PM10, and PM2.5 were collected for particle size analysis and steroid growth promoter analysis. Particle size distributions were generated from TSP samples only, while steroid analysis was conducted on extracts of PM samples using liquid chromatography mass spectrometry. Of seven targeted steroids, 17α-estradiol and estrone were the most commonly detected, identified in over 94% of samples at median concentrations of 20.6 and 10.8 ng/g, respectively. Melengestrol acetate and 17α-trenbolone were detected in 31% and 39% of all PM samples at median concentrations of 1.3 and 1.9 ng/g, respectively. Results demonstrate PM is a viable route of steroid transportation and may be a significant contributor to environmental steroid hormone loading from cattle feedyards.

Process-Based Modeling of Ammonia and Nitrous Oxide Emissions from Open-Lot Beef and Dairy Facilities

Abstract. Airborne emissions, such as ammonia (NH3) and nitrous oxide (N2O), vary considerably among open-lot beef and dairy operations as influenced by climate and manure pack conditions. Because of the challenges with direct measurement, process-based modeling is a recommended approach for estimating airborne emissions from animal feeding operations, such as open lots. The Integrated Farm System Model (IFSM), a whole-farm simulation model for crop, dairy, and beef operations, was previously used (ver. 4.0) to simulate NH3 emissions from open lots and performed well in representing emissions for two beef cattle feedyards in Texas. However, the previous model was found to perform poorly in predicting NH3 emissions measured at two open-lot dairies in Idaho, so further work was done to better represent the effects of climate on lot and manure pack conditions and to integrate better models for nitrification and denitrification processes. The revised model (ver. 4.1) appropriately predicted NH3 emissions for the two Texas beef cattle feedyards, with model predictions having 59% and 81% agreement with measured daily emissions at each lot. Compared to the previous version, the revised model performed better in simulating NH3 emissions for the Idaho open-lot dairies, with 56% to 74% agreement between predicted and measured daily NH3 emissions. For an Idaho dairy with a freestall barn and open lot, the revised model simulated NH3 emissions with 92% agreement between predicted and measured values. Based on measurements obtained at two of the Idaho dairies, IFSM also predicted daily N2O emissions with good agreement (64% to 80%) to measured values. Hence, IFSM can be used to estimate open-lot emissions of NH3 and N2O along with other aspects of performance, environmental impact, and economics of cattle feeding operations in different climatic regions. The model provides a tool for evaluating management strategies to mitigate emissions and improve the sustainability of beef and dairy production systems.

Can Surface-Applied Zeolite Reduce Ammonia Losses from Feedyard Manure? A Laboratory Study

Abstract. Ammonia (NH 3 ) emission from beef cattle feedyard manure results in losses of nitrogen (N), which may negatively affect air, soil, and water quality. The magnitude and rate of NH 3 volatilization from feedyards partially depends on the amount of urinary urea excreted and dissociation of ammonium (NH 4 + ) into NH 3 following urea hydrolysis. Zeolite clinoptilolite is a naturally occurring, porous aluminosilicate mineral that can sorb and sequester cations within its negatively charged framework structure. Zeolite has been used to mitigate NH 3 losses and improve fertilizer value of compost, sewage sludge, and manure in livestock barns; however, few studies have evaluated its efficacy on open-lot beef cattle feedyards. Zeolite application to pen surfaces could be a practical and cost-effective means of reducing NH 3 losses. Objectives of this study were to (1) characterize NH 4 + sorption by zeolites with differing physicochemical properties and (2) evaluate zeolite effects on rates and cumulative losses of NH 3 following application of artificial urine to feedyard manure. Batch incubation studies with four commercially available zeolites revealed that NH 4 + sorption by zeolite was rapid (1 to 2 h) with large differences in sorption potential largely related to zeolite pH. Maximum sorption ranged from 28 to 97 cmol NH 4 + -N kg -1 zeolite. Effects of zeolite application rate [0.5% to 10.0% of manure dry matter (DM)] on sorption and desorption characteristics in a manure/artificial urine matrix were highly variable but tended to be proportional to zeolite application rate: as little as 0.5% zeolite increased NH 4 + -N recovery by up to 19%. In flow-through chamber studies, higher rates of zeolite did not reduce cumulative NH 3 emissions, as 1.0% zeolite reduced cumulative NH 3 emission by 42% and 5.0% zeolite reduced N losses by only 18% compared to unamended manure. Surface application of zeolite has potential for mitigating feedyard NH 3 losses, but specific zeolite properties influenced its effectiveness. Further studies are warranted to evaluate effects of repeated zeolite application, co-application of zeolite and urease inhibitors, and cost:benefit ratios of zeolite application at commercial feedyards.

Airborne particulate matter collected near beef cattle feedyards induces androgenic and estrogenic activity in vitro

Steroid growth promoters are commonly administered to beef cattle residing on feedyards, and a portion of these compounds are excreted in manure along with endogenous steroids. Steroids associated with aerosolized particulate matter (PM) can be transported from feedyards via wind. To assess potential androgenic and estrogenic activity of PM extracts, total suspended particulate samples were collected upwind and downwind of feedyards in the Southern High Plains and subjected to in vitro transcriptional activation assays. Androgen-mediated transcriptional activation induced by exposure to extracts from PM collected downwind of feedyards was significantly higher than that induced by exposure to extracts of corresponding upwind samples, whereas estrogen-mediated transcriptional activation was detected after exposure to upwind and downwind PM sample extracts. Detection and quantitation of metabolites of the synthetic androgen trenbolone acetate downwind, and estradiol both upwind and downwind, suggest that synthetic growth promoters contribute to observed in vitro activity. No significant correlations were observed, however, between individual steroid concentrations or total androgen/estrogen concentration and in vitro activity, indicating the contributions of additional, unquantified compounds to observed androgenic and estrogenic activity. Results indicate that steroids affiliated with feedyard PM have the potential to elicit endocrine-modulating effects.

Antibiotics, bacteria, and antibiotic resistance genes: aerial transport from cattle feed yards via particulate matter.

Background:Emergence and spread of antibiotic resistance has become a global health threat and is often linked with overuse and misuse of clinical and veterinary chemotherapeutic agents. Modern industrial-scale animal feeding operations rely extensively on veterinary pharmaceuticals, including antibiotics, to augment animal growth. Following excretion, antibiotics are transported through the environment via runoff, leaching, and land application of manure; however, airborne transport from feed yards has not been characterized.Objectives:The goal of this study was to determine the extent to which antibiotics, antibiotic resistance genes (ARG), and ruminant-associated microbes are aerially dispersed via particulate matter (PM) derived from large-scale beef cattle feed yards.Methods:PM was collected downwind and upwind of 10 beef cattle feed yards. After extraction from PM, five veterinary antibiotics were quantified via high-performance liquid chromatography with tandem mass spectrometry, ARG were quantified via targeted quantitative polymerase chain reaction, and microbial community diversity was analyzed via 16S rRNA amplification and sequencing.Results:Airborne PM derived from feed yards facilitated dispersal of several veterinary antibiotics, as well as microbial communities containing ARG. Concentrations of several antibiotics in airborne PM immediately downwind of feed yards ranged from 0.5 to 4.6 μg/g of PM. Microbial communities of PM collected downwind of feed yards were enriched with ruminant-associated taxa and were distinct when compared to upwind PM assemblages. Furthermore, genes encoding resistance to tetracycline antibiotics were significantly more abundant in PM collected downwind of feed yards as compared to upwind.Conclusions:Wind-dispersed PM from feed yards harbors antibiotics, bacteria, and ARGs.Citation:McEachran AD, Blackwell BR, Hanson JD, Wooten KJ, Mayer GD, Cox SB, Smith PN. 2015. Antibiotics, bacteria, and antibiotic resistance genes: aerial transport from cattle feed yards via particulate matter. Environ Health Perspect 123:337–343; http://dx.doi.org/10.1289/ehp.1408555

Increasing Stocking Density Reduces Emissions of Fugitive Dust from Cattle Feedyards

<abstract><title><italic>Abstract. </italic></title> The moisture and compaction dynamics of an open-lot corral surface in a cattle feedyard depend strongly on the spatial density at which the animals are stocked. Because the moisture content and bulk density of the corral surface directly influence its intrinsic dust susceptibility, emission of fugitive dust from a feedyard surface should be sensitive to changes in stocking density. In the summer of 2012 we measured airborne dust concentrations upwind and downwind of feedyard pens stocked at two different densities, 718 (control) and 1,435 hd ha^-1, over a 160-d feeding period. Doubled stocking density was achieved in two different ways, by (A) confining cattle to half the pen area using electric cross-fencing and (B) doubling the number of cattle in the pens. Path-averaged dust concentrations were measured upwind and downwind of feedyard pens using an optical particle sizer (OPS model 3330, TSI Inc., Shoreview, Minn.) and an earlier-model optical sensor (model DUSTTRAK II 8530, TSI Inc., Shoreview, Minn.) mounted on mobile monitoring platforms. Because the monitoring platforms used different instruments, during the data analysis phase DUSTTRAK data were compared only to DUSTTRAK data, and OPS data were compared only to OPS data. Downwind 1-min concentrations of dust varied from 1 to 4,478 μg m^-3 for the control pens, 1 to 2,431 μg m^-3 for the pens with cross-fencing (treatment A), and 1 to 2,872 μg m^-3 for the pens with twice as many cattle as the control pens (treatment B). Dispersion modeling using AERMOD revealed that the apparent dust-emission fluxes from treatments A and B were 79.4% and 80.6% lower, respectively, than the apparent emission flux from the control pens (23.45 μg m^-2 s^-1). We conclude that stocking-density manipulation is likely to be a viable Beneficial Management Practice (BMP) for controlling fugitive dust from open-lot cattle feedyards but that improved, path-averaged monitoring techniques appropriate to the feedyard source geometry are needed.

Air quality in open-lot dairies and cattle feedyards

The research community is making good progress in understanding the mechanical, biochemical, and atmospheric processes responsible for airborne emissions of particulate matter (PM, or “dust”), gases, and vapors from open-lot livestock production, especially dairies and cattle feedyards. Recent studies in Texas, Kansas, Nebraska, Colorado, California, and Australia have expanded the available data on both emission rates and abatement measures. A national guidance document published by USDA last summer established what researchers believe to be the state of the art in estimating greenhouse-gas emissions from individual facilities. Although the uncertainties associated with our estimates of fugitive emissions are still unacceptably high, we have learned from our recent experience with ammonia that using a wide variety of credible measurement techniques, rather than focusing on 1 so-called “standard” technique, may be the better way to improve confidence in our estimates. The most promising control measures for gaseous emissions continue to be dietary strategies to increase nutrient-use efficiency, with management of corral-surface moisture a close second. For particulate matter, corral-surface management and moisture management may play comparable roles, depending on the mechanical strength of soils and the availability of water, respectively. The cost per unit reduction of emitted mass attributable to these abatement measures varies as widely as the emissions estimates themselves. Therefore, continued emphasis on process-based emissions research to reduce variances in emissions estimates, and to mitigate the contingency of prior, empirically based estimates is necessary. As a general rule, although cattle feedyard emission factors may be considered a reasonable starting point for estimating emissions from open-lot dairies, such estimates should be viewed with suspicion.