Progress 06/15/07 to 06/14/11
Outputs
OUTPUTS: For three years, water samples were collected biweekly from upstream and downstream sites of streams in 13 pastures stocked at 0 to 32 cow-days/stream m/year in the Rathbun Lake watershed in southcentral Iowa and analyzed for the concentrations of total coliforms and the presence of bovine enterovirus (BEV), bovine coronavirus (BCV), and bovine rotavirus (BRV). Concentrations of total coliforms in upstream and downstream samples did not differ (P = 0.31) and were not related to the annual stocking densities of the pastures. Mean incidences of BEV, BCV, and BRV in upstream and downstream water samples were 3.91, 1.12, and 0.49% and did not differ between sampling sites. Incidence of BEV in downstream samples was related to the presence of cattle on the day of sampling (P = 0.09) and rainfall events 24 and 72 hours before sampling. Incidences of BCV and BRV in downstream samples were related (P < 0.05) to rainfall events on the day of sampling. For two years, six 12.1 ha pastures bisected by Willow Creek in central Iowa were stocked with 15 fall-calving Angus cows to graze by continuous stocking with unrestricted stream access (CSU) or with stream access restricted to stabilized sites (CSR) or by rotational stocking (RS) from May through October. As measured with GPS collars, cattle in CSU, CSR and RS pastures were present in the stream 1.8, 0.35, and 0.09% of the time. In June, August, and September, BEV was shed in the feces of 4.4, 28.8, and 41.1% of the cows in 2008 and 28.9, 18.9, and 13.3% of the cows in 2009. Bovine coronavirus was shed by one cow in August 2008 and BRV and Escherichia coli O157:H7 were shed by no cows. In rainfall simulations conducted on the stream banks in each pasture in April, June, August, and October of the 2 years, BEV was present in 8.3 and 16.7% of the samples from bare sites in the CSU pastures in June and October, 2008 and in 8.3% of the samples from vegetated sites in the CSU pastures in April, 2009. Escherichia coli O157:H7, BCV, and BRV were not detected in runoff samples during the study. Project results were used in a web-based course entitled 'Environmental Management of Livestock. Grazing and Pathogen Issues' at Iowa State University. Project results were also used in the 'Grazing Management for Water Quality Protection' webcast through the Livestock and Poultry Environmental Learning Center in 2009, the 'Optimizing Grazing and Enhancing the Environment Conference' at Moravia, IA in 2009, a Riparian Grazing Field Day at the Rhodes Research Farm in 2009, the 'Environmental Impact of Forage-Based Livestock Production Systems Symposium' at the annual meeting of the American Society of Animal Science in Denver, CO in 2010, and the Northeast Grazing Consortium at State College, PA in 2011. The project also produced 3 M.S. theses and the respective graduate students. Two papers have been published in refereed journals, one is in review, and one is in preparation for submission to a refereed journal. Results were also presented to scientists in 9 abstracts at professional meetings and to producers and extension personnel in 7 leaflets in the annual Iowa State University Animal Industry Report. PARTICIPANTS: The Principal Investigators were Drs. J.R. Russell in the Department of Animal Science and Drs. S.M. Ensley and K.-J. Yoon of the Department of Veterinary Diagnostic and Production Animal Medicine at Iowa State University. The project was also assisted by Dr. N.A. Cornick from the Department of Veterinary Microbiology at Iowa State University. Training opportunities were provided for 3 graduate students: D.A. Bear and K.A. Schwarte who have completed their M.S. degrees and Y.-I. Cho who is in the process of completing his M.S. degree. In addition, the Livestock and Poultry Environmental Learning Center at the University of Nebraska-Lincoln, who collaborated in a webinar in 2009, and the Brenton Center for Agriculture and Technology Transfer at Iowa State University, who provided the resources for developing and delivering the web-based course entitled 'Environmental Management of Livestock. Grazing and Pathogen Issues'. Also, the Rathbun Land and Water Alliance and Wayne County Soil and Water Conservation District have provided financial and technical assistance as well as identifying cooperating producers for on-farm studies in this project. TARGET AUDIENCES: The results of this project are primarily targeted to assist operators of beef cow-calf farms in the Midwest in the cost-effective management practices to reduce pathogen loading of pasture streams. Furthermore, the results also assist governmental agency and extension personnel who advise producers in the development of cost-effective management practices to limit pathogen loading of streams in pastures with specific characteristics. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Manure deposition in or near pasture streams has been suggested as a major source of coliform bacteria in surface water sources, indicating contamination with pathogenic intestinal bacteria. However, coliform bacteria are an inadequate indicator of pathogen loading by grazing cattle as coliform bacteria in the feces of grazing cattle are indistinguishable from coliform bacteria from other sources when measured by culture techniques. As a result, there were no differences in the concentrations of total coliform bacteria in water samples collected from streams at sites upstream and downstream of pastures and there were no relationships between total fecal coliform concentrations with cattle stocking densities ranging from 0 to 32 cow-days/stream m/year or with the incidences of intestinal viruses associated with cattle in water samples from pasture streams. Because bovine enterovirus (BEV) is shed primarily by cattle, it has been proposed as a more acceptable indicator of fecal loading of surface water resources from cattle than coliform bacteria. However, incidence of BEV was only 3.9% in water samples collected from 13 pastures in the Rathbun Lake watershed over 3 years and did not differ between water samples collected upstream and downstream of the pastures. Furthermore, BEV was shed by only 24.3% of the cows and collected in 0 to16.7% of the runoff samples from the rainfall simulations on the banks of streams in the pastures in the Willow Creek watershed over two years. Incidences of bovine coronavirus (BCV) and bovine rotavirus (BRV) in water samples from streams in 13 pastures in the Rathbun Lake watershed were only 1.1 and 0.5%, respectively, were not related to pasture stocking density, and did not differ between samples collected upstream and downstream of the pastures. Bovine coronavirus was shed by only one cow and BRV and Escherichia coli O157:H7 were shed by no cows in the pastures in the Willow Creek watershed over two years. Therefore, these pathogens were not detected in runoff samples from rainfall simulations conducted on the stream banks. However, the significant relationship between the incidence of BCV and BRV in water samples collected downstream of the pastures in the Rathbun Lake watershed and precipitation on the day of sampling imply that precipitation runoff from pastures may transport pathogenic viruses to surface water resources. When deposited near pasture streams, transport of intestinal viruses is greater from bare ground than vegetated areas on stream banks. As a result, loading of pathogens of pasture streams is infrequent and is controlled, in order, by the incidence of shedding, the distribution of manure near pasture streams, and the transport of viruses as affected by the proportion of bare ground near pasture streams. As the distribution of manure and bare ground are controlled by the distribution of cattle in a pasture, producers may reduce pathogen loading of pasture streams by implementing grazing management practices that reduce congregation of cattle near pasture streams such as restricting stream access to stabilized crossings or a riparian paddock.
Publications
- Schwarte, K.A., Russell, J.R., and Morrical, D.G. 2011. Effects of pasture management and off-stream water on temporal/spatial distribution of cattle and stream bank characteristics in cool-season grass pasture. J. Anim. Sci (Accepted for publication)
- Bear, D.A., Russell, J.R., and Morrical, D.G. 2012. Physical characteristics, shade distribution, and tall fescue effects on cow temporal/spatial distribution in Midwestern pastures. Rangeland Ecol. Manage. (In review)
- Bear, D.A., Russell, J.R. and Morrical, D.G. 2010. Effects of microclimate and pasture characteristics on temporal/spatial distribution of beef cows in Midwestern pastures. Abstracts of the ADSA-PSA-AMPA-CSAS-WSASAS-ASAS Joint Annual Meeting, Denver, CO, CD-ROM Abstract 92.
- Bear, D.A., Russell, J.R., and Morrical, D.G. 2010. Pasture management effects on nonpoint source pollution of Midwestern pastures. P. 209. Proceedings of the 4th Grazing Livestock Nutrition Conference, Estes Park, CO.
- Russell, J.R., D.A. Bear, K.A. Schwarte, and M.M. Haan. 2010. Pasture management strategies to minimize the impacts of grazing on water quality of surface water resources. Abstracts of the ADSA-PSA-AMPA-CSAS-WSASAS-ASAS Joint Annual Meeting, Denver, CO, CD-ROM Abstract 634.
- Schwarte, K.A., Russell, J.R., Kovar, J.L., Morrical, D.G., Ensley, S.M., Yoon, K.-J., Cornick, N.A., and Cho, Y.-L. 2011. Grazing management effects on sediment, phosphorus, and pathogen loading of streams in cool-season grass pastures. J. Environ. Qual. 40:1303-1313.
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Progress 06/15/09 to 06/14/10
Outputs
OUTPUTS: At increased ambient temperatures, grazing cattle will congregate in riparian areas if allowed unrestricted stream access increasing the concentration of manure while decreasing vegetative cover near the streams. However, over three years, mean concentrations of total coliforms did not differ in water samples from upstream and downstream sites on streams in thirteen pastures in the Rathbun Lake watershed in Iowa and were not related to annual stocking densities of the pastures. Mean concentrations of total coliforms in upstream and downstream water samples were greater in April through July than March and September. Incidences of Bovine enterovirus (BEV), Bovine coronavirus (BCV), Bovine rotavirus (BRV), and E. coli O157:H7 in 1254 water samples collected from upstream and downstream sites in the thirteen pastures were 49 (3.91%), 14 (1.12%), 6 (0.49%), and 0, but did not differ between upstream and downstream samples and were not related to annual cattle stocking densities of the pastures. Incidence of BEV tended to be related to cattle presence on the sampling day in downstream water samples and tended to be related to cattle presence on the day of sampling and one, two, and three days prior to sampling in upstream samples. Incidences of BCV, BRV, and E. coli O157:H7 in water samples were not related cattle presence on the day of sampling. Incidences of BEV and BCV in upstream and downstream water samples tended to be related to rainfall occurring 1 day prior to sampling, but not related to rainfall which occurred 2 and 3 days prior to sampling. Incidence of BRV was related to rainfall which occurred on the day of sampling. Incidences of BEV shedding in the feces of 90 cows in six pastures on a farm in the Willow Creek watershed in Iowa in June, August, and September were 1.1, 28.8, and 41.1% in 2008 and 38.9, 18.9, and 13.3% in 2009. One cow shed BCV in August, 2008 and no cows shed BRV or E. coli O157:H7 in 2008 or 2009. Bovine enterovirus was found in 8.3 and 16.7% of the runoff samples from rainfall simulations on bare sites on stream banks in pastures with continuous stocking and unrestricted stream access (CSU) in June and October, 2008. However, BEV was not present in runoff samples from vegetated or bare sites in pastures with rotational stocking (RS) or continuous stocking with restricted stream access (CSR) and BRV, BCV, and E. coli O157:H7 were not detected in rainfall simulations on vegetated or bare sites in pastures with CSU, RS, or CSR grazing management systems. Results of this project were presented to stakeholders in a webcast entitled 'Grazing Management for Water Quality Protection' through the Livestock and Poultry Environmental Learning Center, the 'Optimizing Grazing and Enhancing the Environment' conference at Promise City, Iowa, and the Northwest Iowa Pasture Walk at Cushing, Iowa. In addition, results have been presented to producers, agency personnel, and other researchers in presentations or posters at the National Grazing Lands Initiative (Sparks, NV), Midwestern Sectional Meeting of the American Society of Animal Science (Des Moines, IA), and the National Water Conference (Hilton Head, SC). PARTICIPANTS: Faculty: J.R. Russell, S.M. Ensley, K.-J. Yoon. and N.A. Cornick. Training opportunities are provided for 3 graduate students: D.A. Bear, K. Schwarte, and Y.-I. Cho, who are all working on MS degrees. In addition, the Rathbun Land and Water Alliance and the Wayne County Soil and Water Conservation District have provided financial and technical assistance as well as cooperating producers for the on-farm studies in this project. The Leopold Center for Sustainable Agriculture has provided additional support for this research. TARGET AUDIENCES: The results of this project are primarily targeted to assist operators of beef cow-calf farms in the Midwest in development and implementation of cost-effective management strategies for pasture streams to minimize pathogen loading and reduce the risks to human and cattle health. Furthermore, the results will also assist governmental agency personnel and extension educators who work with producers in developing the best management practices to limit nonpoint source water pollution on specific farms. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Previous research has shown that if provided unrestricted stream access, grazing cattle may increase the concentrations of coliform bacteria in pasture streams. However, in this study, concentrations of total coliforms did not differ in water samples from up- and down-stream sites, implying that other sources contribute to coliform loading. Furthermore, as coliform concentrations were not related to pathogen incidence, total coliforms appear to be an ineffective indicator of pathogen loading. While not a human pathogen, Bovine enterovirus (BEV) has been proposed as a specific indicator of contamination with bovine feces. In this study, incidence of BEV in water samples from pasture streams was related to the presence of cattle in that pasture up three days prior to sampling. However, BEV was shed in the feces by an average of 23.7% of the cows tested and the incidence of BEV in water samples from pasture streams was not related to the pathogens, Bovine Rotavirus (BRV) and Coronavirus (BCV). Incidences of BRV and BCV in water samples from pasture streams were low and not related to pasture stocking rate, but were related to rainfall on the day of sampling or 1 day before sampling, respectively, implying their transport in precipitation runoff if shed by the cattle. Incidence of shedding of BCV was low and BRV was not shed by the cows in pastures grazed by continuous stocking with unrestricted stream access (CSU), continuous stocking with stream access restricted to stabilized crossings (CSR), or rotational stocking (RS) and no BRV or BCV were detected in runoff from rainfall simulations conducted on bare or vegetated sites on stream banks in these pastures. However, because runoff was 4.9 times greater from bare sites in CSU and RS pastures than vegetated sites in CSR pastures and the incidence of BEV in runoff was greater from bare sites than vegetated sites, grazing management practices to maintain adequate vegetation on stream banks will minimize the risks of pathogen loading when these viruses are shed. Restricting stream access either to stabilized crossings in CSR pastures or riparian paddocks in RS pastures decrease the percentage of feces and bare soil on and within 33 m of stream banks by decreasing the percentage of time that cattle are in the stream by 79 and 70% and are within 33 m of the stream by 78 and 57%, respectively, compared to CSU management. Therefore, risks of pathogen loading of pasture streams will be reduced by grazing management practices that minimize congregation of cattle near pasture streams which may include restricting stream access to stabilized crossings or rotational grazing as well as complete exclosure. However, as congregation of cattle in riparian areas of pastures in five farms in the Rathbun Lake watershed was more highly related to pasture size than pasture botanical composition or shade distribution, the best management practice to minimize pathogen loading in an individual pasture will site-specific depending on the pasture physical as well as botanical characteristics. These results have been disseminated not only in publications, but through webinars, field days, and a web-based class.
Publications
- Schwarte, K.A., J.R. Russell, and D.G. Morrical. 2010. Effects of pasture management and off-stream water on temporal/spatial distribution of cattle in cool-season grass pastures. Abstracts of the 2010 Meeting of the Midwestern Section of the American Dairy Science Association and American Society of Animal Science 88, E-Suppl. 3:97.
- Schwarte, K.A., J.R. Russell, and D.G. Morrical. 2010. Microclimate Effects on the Temporal/Spatial Distribution of Beef Cows Grazing Cool-Season Grass Pastures by Different Management Practices. R2529. 2010 Animal Industry Report. Iowa State University, Ames.
- Schwarte, K.A. and Russell, J.R. 2009. Grazing management effects on the sward and physical characteristics of cool-season grass pastures relative to streams. Proceedings and Abstracts: 2009 Annual Conference of the American Forage and Grassland Council. Grand Rapids, MI, CD-ROM.
- Schwarte, K.A., J.R. Russell, S. Ensley, K.J. Yoon, and D.G. Morrical. 2010. Effects of cattle presence on sediment, phosphorus, and pathogen loading of streams in cool-season grass pastures. Abstracts of the 2010 Meeting of the Midwestern Section of the American Dairy Science Association and American Society of Animal Science 88, E-Suppl. 3:81.
- Schwarte, K.A. and J.R. Russell. 2010. Grazing management effects on streambank characteristics and surface run-off into pasture streams. R2530. 2010 Animal Industry Report. Iowa State University, Ames.
- Cho Y-I, Bear DA, Russell J, Ensley SM, Kim W-I, Yoon KJ. 2010. Survey of bovine enteric viruses in Midwestern pasture streams. Abstract, KSEA Midwest Regional Conference (not numbered).
- Bear, D.A., J. Russell, Y.-I. Cho, S. Ensley, and K.-J. Yoon. 2009. Incidences of bovine enterovirus, coronavirus, rotavirus group A and concentrations of fecal coliforms in Midwestern pasture streams. Proceedings of the National Conference on Grazing Lands, Sparks, NV, CD-ROM.
- Bear, D.A., Y.-I. Cho, J.R. Russell, S. Ensley, and K.-J. Yoon. 2010. Incidence of Bovine Enterovirus, Coronavirus, and Group A Rotavirus, and concentration of Total Coliforms in Midwestern pasture streams. R2532. 2010 Animal Industry Report. Iowa State University, Ames.
- Bear, D.A. and J.R. Russell. 2009. Effects of microclimate and physical and botanical characteristics on temporal/spatial distribution of beef cows in Midwestern cool-season grass pastures. Proceedings and Abstracts: 2009 Annual Conference of the American Forage and Grassland Council. Grand Rapids, MI, CD-ROM.
- Bear, D.A., J.R. Russell, and D.G. Morrical. 2010. Cattle Temporal & Spatial Distribution in Midwestern Pastures Using Global Positioning (A Three-Year Progress Report). R2509. 2010 Animal Industry Report. Iowa State University, Ames.
- Russell, J.R., S.M. Ensley, and K.-J. Yoon. 2010. Grazing management effects on pathogen loading of Midwestern Pasture Streams. USDA National Water Conference. Hilton Head, SC, (CD-ROM).
- Schwarte, K.A. and J.R. Russell. 2009. Microclimatic effects on the temporal\spatial distribution of beef cows grazing cool-season grass pastures by different management practices. Proceedings and Abstracts: 2009 Annual Conference of the American Forage and Grassland Council. Grand Rapids, MI, CD-ROM.
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Progress 06/15/08 to 06/14/09
Outputs
OUTPUTS: In biweekly water samples, collected in 2007 and 2008, from the up- and downstream sites on streams in 13 pastures with annual stocking rates of 0 to 333 cow-days/acre in the Rathbun Lake watershed in southern Iowa, mean fecal coliform concentrations were 930 and 938 colony-forming units/100 ml and were not related to pasture stocking rate. Mean incidences of bovine enterovirus (BEV), bovine coronavirus (BCV), and bovine rotavirus (BRV) were 5.42, 1.60, and 0.25% and did not differ between up- and downstream samples. Incidences of BEV in up- and downstream samples were related to cattle presence on the day of sampling and three days prior to sampling and decreased if there was rainfall on the day of sampling or 24, 48, or 72 hours prior to sampling. Shedding of E. coli O157:H7 occurred in 16% of 90 fall-calving cows in six 30-acre smooth bromegrass pastures in the Willow Creek watershed in central Iowa managed by continuous stocking with unrestricted (CSU) or restricted (CSR) stream access or rotational stocking (RS) in September 2007, but did not occur in any other month in 2007 or 2008. Bovine enterovirus was shed by 1.1, 28.9, and 41.1% of the cows in June, August, and September, 2008 and BRV was shed by 1.1% of the cows in September, 2008. There were no incidences of E. coli O157:H7, BEV, BCV or BRV in the runoff from rainfall simulations on bare and vegetated sites along the banks of Willow Creek in June or August, 2008 or April, 2009. However, BEV was present in 16.5% of the runoff samples from bare sites in pastures with CSU in October, 2008. Because the risk of pathogen loading of pasture streams may be affected by the temporal/spatial distribution of grazing cattle, cow position was measured using GPS. Mean percentages of time that cows were in or within 30.5 m of streams in pastures on 5 cooperating farms in the Rathbun Lake watershed ranged from 4.6 to 24.2% during the 2007 and 2008 grazing seasons and were related to the proportion of the pasture within 30.5 m of the streams. In 2008, cows grazing the pastures in the Willow Creek watershed by CSU, CSR and RS spent 2.1, 9.1; 0.4, 2.7; and 0.1, 1.7% of the time in and within 33.5 m of the stream. Project results were the basis of the A Guide to Managing Pasture Water publication series distributed through Iowa State University Extension, a Riparian Grazing Workshop for USDA-NRCS, Soil and Water Conservation District, and Cooperative Extension personnel at the McNay Research Farm (Chariton, IA), a series of lectures in a web-based course (An S/Agron 543X) entitled Environmental Management of Livestock, and a Riparian Grazing Field Day at the Rhodes Research Farm (Rhodes, IA). Results were also reported in presentations at the annual field day of the McNay Research Farm (Chariton, IA) and the annual meeting of the American Forage and Grassland Council (Grand Rapids, MI), in posters at the Iowa Farm Bureau's Water Quality Conference (Des Moines, IA) and the USDA-CSREES Water Quality Conference (St. Louis, MO), and in papers in the 2008 Animal Industry Report (Iowa State University). PARTICIPANTS: Faculty: J.R. Russell, S.M. Ensley, K.-J. Yoon. and N.A. Cornick. Training opportunities are provided for 3 graduate students: D.A. Bear, K. Schwarte, and Y.-I. Cho, who all working on MS degrees. In addition, the Rathbun Land and Water Alliance and the Wayne County Soil and Water Conservation District have provided financial and technical assistance as well as cooperating producers for the on-farm studies in this project. The Leopold Center for Sustainable Agriculture has provided additional support for this research. TARGET AUDIENCES: The results of this project are primarily targeted to assist operators of beef cow-calf farms in the Midwest in the cost-effective management of pasture streams to reduce pathogen loading and improve cattle health. Furthermore, the results will also assist governmental agency personnel and extension educators who work with producers in developing the best management practices to limit nonpoint source water pollution on specific farms. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The presence of pathogens is the fifth and seventh most common impairment of water in Iowa streams and lakes and is, at least partially, responsible for nearly 20% of the water bodies on the impaired waters list in Iowa. High concentrations of fecal coliform bacteria in the water of streams entering pastures, the lack of a net increase or an effect of stocking rate on the concentrations of fecal coliforms in streams leaving pastures, and the lack of net increases in the incidences of bovine enterovirus (BEV), bovine coronavirus (BCV), and bovine rotavirus (BRV) between up- and downstream water samples imply that sources of fecal coliforms and pathogenic viruses other than grazing cattle are major contributors to pathogen loading of pasture streams. Furthermore, there is little relation between the presence of fecal coliforms and pathogenic viruses in pasture streams. The low frequency and seasonality of shedding of E. coli O157:H7 and viral pathogens implies that grazing cattle pose a small risk of pathogen loading of streams in spring and summer. The increased incidence of E. coli O157:H7 and BEV in the feces of fall-calving cows in September suggests that grazing cattle may pose a risk of pathogen loading in the autumn months which may be aggravated by calving. This risk is supported by the presence of BEV in 16.5% of water samples from bare sites in pastures with unrestricted stream access in September, 2008. This risk may be minimized by grazing practices such as restricting stream access to stabilized crossings or rotational stocking that reduce the proportion of bare ground or manure near pasture streams by altering the temporal/spatial distribution of grazing cattle. Over 3 years, cows allowed unrestricted access to streams in replicated pastures spent an average of 1.1 to 2.1% of the time in the pasture stream and 9.1 to 10.5% of the time within 33.5 m of the stream when these areas represented 1 and 6.5% of the pasture, respectively. In contrast, restricting access of pasture streams to grazing cows by using stabilized crossings or rotational stocking reduces the percentages of time that cattle are in streams by 80 to 95% and within 33.5 m of the streams by 70 to 81%. Similarly, providing off-stream water reduces of congregation of cattle near pasture streams in warm weather if natural sources of off-stream water are not available. Thus, rotational stocking, stabilized crossings, or off-stream water are alternatives to complete exclusion as methods to prevent pathogen loading of pasture streams. While factors like the presence of tall fescue or the distribution of shade within pastures was expected to affect congregation of cattle near pasture streams, the proportion of time that cattle congregated within 30.5 m of streams in pastures on 5 cooperating farms in the Rathbun Lake watershed was related to the proportion of total pasture area within 30.5 m of the pasture streams as affected by pasture size and shape. Thus, the effectiveness of grazing management practices to reduce pathogen loading of pasture streams by altering cattle congregation in riparian areas will depend on to the characteristics of each site.
Publications
- Bear, D.A. and Russell, J.R. 2009. Effects of microclimate and physical and botanical characteristics on temporal\spatial distribution of beef cows in Midwestern cool-season grass pastures. Annual Conference of American Forage and Grassland Council, Grand Rapids, MI (CD-ROM).
- Bear, D.A. and Russell, J.R. 2009. Cattle temporal and spatial distribution in Midwestern pastures using global positioning (A progress report). A.S. Leaflet R2402. Iowa State University Animal Industry Report 2009 (CD-ROM).
- Schwarte, K.A. and Russell, J.R. 2009. Microclimate effects on the temporal\spatial distribution of beef cows grazing cool-season grass pastures by different management practices (A progress report). A.S. Leaflet R2440. Iowa State University Animal Industry Report 2009 (CD-ROM).
- Schwarte, K.A. and Russell, J.R. 2009. Grazing management effects on the sward and physical characteristics relative to streams in cool-season grass pastures. A.S. Leaflet 2439. Iowa State University Animal Industry Report 2009 (CD-ROM).
- Bear, D.A., Cho, Y.-I., Russell, J.R., Ensley, S.M., and Yoon, K.-J. 2009. Incidence of bovine enterovirus, coronavirus, and group A rotavirus, and concentrations of fecal coliforms in Midwestern pasture streams. A.S. Leaflet R2442. Iowa State University Animal Industry Report 2009 (CD-ROM).
- Bear, D.A., Russell, J.R., Cho, Y.-I., Ensley, S.M., and Yoon, K.-J. 2009. Incidences of bovine enterovirus, coronavirus, and rotavirus group A, and concentrations of fecal coliforms in Midwestern pasture streams. Annual Conference of American Forage and Grassland Council, Grand Rapids, MI (CD-ROM).
- Russell, J.R., Ensley, S.M., and Yoon, K.-J. 2009. Grazing management effects on pathogen loading of Midwestern pasture streams. USDA-CSREES National Water Conference, St. Louis, MO.
- Russell, J. and S. Shouse. 2008. A Guide to Managing Pasture Water: Stabilized Stream and Pond Access Sites. p. 4. Iowa State University Extension. Ames, IA.
- Russell, J., M. Haan, and D. Strohbehn. 2008. A Guide to Managing Pasture Water: Off-stream Water, Shade, and Nutritional Supplementation to Modify Animal Behavior. p. 4. Iowa State University Extension. Ames, IA.
- Schwarte, K.A. and Russell, J.R. 2009. Microclimate effects on the temporal\spatial distribution of beef cows grazing cool season grass pasture by different management practices. Annual Conference of American Forage and Grassland Council, Grand Rapids, MI (CD-ROM).
- Schwarte, K.A. and Russell, J.R. 2009. Grazing management effects on the sward and physical characteristics of cool season grass pastures relative to streams. Annual Conference of American Forage and Grassland Council, Grand Rapids, MI (CD-ROM).
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Progress 06/15/07 to 06/14/08
Outputs
OUTPUTS: In water samples taken biweekly from the up- and downstream ends of streams in 13 pastures with annual stocking rates of 0 to 716 cow-days/ha in the Rathbun Lake watershed, the mean downstream concentration and net increase in fecal coliforms were 469 and 32 colony-forming units/100 ml and did not differ between pastures. Mean incidences of bovine coronavirus and rotavirus were 0.48% and did not differ between pastures. Duplicate pastures grazed by continuous stocking with unrestricted access to the streams (CSU) in the Willow Creek watershed for 3 years had greater proportions of bare ground on the stream banks in October and within 35.5 m of the stream banks in September than pastures grazed by rotational stocking (RS) or continuous stocking with stream access restricted to stabilized crossings (CSR). Proportions of fecal-covered ground did not differ in pastures grazed by CSU or RS, but were greater in these pastures than pastures grazed by CSR on the stream banks in July through October and within 35.5 m of the stream banks in August through October. In the 13 pastures in the Rathbun Lake watershed, the proportion of bare ground within 17.1 m of the streams was not related to the annual stocking rates. But in stepwise multiple regression, the proportion of fecal-covered ground within 17.1 m of the streams could be predicted (r-square = 0.61) by the stocking rate/m stream and the proportions of vegetation comprised of tall fescue, smooth bromegrass, and reed canarygrass in each measurement period. Using GPS collars, cows grazing pastures in the Willow Creek watershed by CSU spent greater proportions of time in the stream (1.1%) and within 35.5 m of the streams (10.5%) from May through September than pastures grazed by RS and CSR (0.2 and 1.7%). As the probability of cows being within 35.5 m of the streams increased by 12.1 and 5.8 %/degree C increase in ambient temperature in pastures grazed by CSU and CSR, treatment differences in the proportion of time that cattle were in the streams were greater in June and July than other months. Providing off-stream water to cows grazing in pastures by CSU decreased the proportion of time cattle were within 35.5 m of the stream in each month. In 5 pastures in the Rathbun Lake watershed, the probabilities of cattle being within 32.3 m of the streams increased from 1.7 to 26.7%/1 degree C increase in ambient temperature and were related to the proportion of the pasture within 32.3 m of the streams. Although E coli O157:H7 was not found in the feces of the cows grazing the pastures in the Willow Creek watershed in July or August, the incidence of E coli O157:H7 shedding in the feces was 14.8% in the cows grazing these pastures in September and did not differ between grazing treatments. Results were reported in field days at the Rhodes and McNay Research Farms, in presentations at the annual conference of the Iowa Forage and Grassland Council (Des Moines, IA), and the Cornbelt Cow-calf Conference (Ottumwa, IA) and in a paper in the 2008 Animal Industry Report (Iowa State University). PARTICIPANTS: Faculty: J.R. Russell, S.M. Ensley, K.-J. Yoon. and N.A. Cornick. Training opportunities are provided for 3 graduate students: D.A. Bear, K. Schwarte, and Y.-I. Cho, who all working on MS degrees. In addition, the Rathbun Land and Water Alliance and the Wayne County Soil and Water Conservation District have provided financial and technical assistance as well as cooperating producers for the on-farm studies in this project. TARGET AUDIENCES: The results of this project are primarily targeted to assist operators of beef cow-calf farms in the Midwest in the cost-effective management of pasture streams to reduce pathogen loading and improve cattle health. Furthermore, the results will also assist governmental agency personnel and extension educators who work with producers in developing the best management practices to limit nonpoint source water pollution on specific farms. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The presence of pathogens is the fifth and seventh most common impairment of water in Iowa streams and lakes and is, at least partially, responsible for nearly 20% of the water bodies on the impaired waters list in Iowa. High concentrations of fecal coliform bacteria in the water of streams leaving pastures would seem to imply that grazing cattle could be a major source of pathogen loading of water sources. While there is a net increase in the concentration of fecal coliforms across pastures, the high concentrations of fecal coliform bacteria in stream water entering the pastures and the lack of a relation between fecal coliform concentrations and pasture stocking rates imply that other sources of fecal coliforms are major contributors to the pathogen load. This result implies that fecal coliform concentrations in pasture streams may not be greatly affected by preventing cow access to pasture streams. However, fecal coliform concentrations are not highly related to the presence of intestinal pathogens in the water of pasture streams. Bovine coronavirus and rotavirus were not detected in stream water until fall implying seasonality in shedding and/or survival of the viruses in the environment. Seasonality was observed in the shedding of E coli O157:H7 by cows. This seasonality in the presence of the pathogens in feces and/or water imply that the use of grazing or pasture management practices to control pathogen loading of pasture streams may be most effectively employed in late summer and fall. Providing cattle uncontrolled access to pasture streams increases the proportion of ground that is bare on and near stream banks in late summer and early fall. Similarly providing cattle uncontrolled access to pasture streams increases the proportion of ground that is covered with feces on and near stream banks throughout the grazing season and the concentration of fecal-covered ground increases with an increasing stocking rate. These conditions increase the possibility of pathogen loading of pasture streams from precipitation run off in the fall when cattle have a greater probability of shedding pathogens. The proportions of bare and fecal-covered ground on and near stream banks as well as direct loading of feces into streams can be reduced by restricting stream access by using stabilized crossings or rotational stocking by reducing the proportion of time cattle are present within the riparian zone. The effects of altering of the temporal/spatial distribution of cattle through the use of stabilized crossings, rotational stocking or providing off-stream water increase with increasing temperatures. Similarly, the relationship between climatic conditions and the temporal/spatial distribution of cattle within pastures is modified by the shape and size of the pasture. These results imply that the most effective management practices to minimize pathogen loading of pasture streams will be site and seasonally specific and can be identified through model development.
Publications
- Russell, J.R., M.M. Haan, D.A. Bear, Y.-I. Cho, S.M Ensley, K.-J. Yoon and N.A. Cornick. 2008. Grazing management effects on pathogen loading of Midwestern pasture streams. 2008 USDA-CSREES National Water Conference, Sparks, NV
- Haan, M.M., J.R. Russell, D. Morrical, and D. Strohbehn. 2008. Effect of grazing management on cattle distribution patterns in relation to pasture streams. A.S. Leaflet R2268. Iowa State University Animal Industry Report 2008. Ames, IA
- Haan, M.M., J.R. Russell, D. Morrical, and D. Strohbehn. 2008. Effects of grazing management on the physical and nutritional characteristics of pastures. A.S. Leaflet R2323. Iowa State University Animal Industry Report 2008. Ames, IA
- Russell, J.R., D.A. Bear, M.M. Haan, M. Tufekcioglu, D.G. Morrical, T.M. Isenhart, and J.L. Kovar. 2008. Effects of stocking rate and botanical composition on the physical characteristics of the riparian zones of pastures. A.S. Leaflet R2324. Iowa State University Animal Industry Report 2008. Ames, IA
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