A dairy herd submodel was created for integration with other farm submodels to form DAFOSYM, a dairy farm simulation model. The herd submodel determines the best mix of available feeds to meet the fiber, energy, and protein requirements for each of six animal groups. The groups are early-, mid-, late-, and nonlactating cows, heifers over 1 yr old, and younger heifers. Feed intake, milk producti...

A case study of the Central Vermont Public Service Corporation (CVPS) Cow Power program examines the economic feasibility for dairy farms to convert cow manure into electricity via anaerobic methane digestion. The study reviews the mechanism for CVPS, dairy farms, electricity customers, and government agencies to develop and operate the program since 2004, examines the costs and returns for the...

Federal and state regulations are being promulgated under the Clean Air Act to reduce hazardous air emissions from livestock operations. Few data are available on emissions from livestock facilities in the USA and the management practices that may minimize emissions. The objective of this study was to measure seasonal and bedding impacts on ammonia emissions from tie-stall dairy barns located i...

Contamination by bacteria is a leading cause of impairment in U.S. waters, particularly in areas of livestock agriculture. We evaluated the effectiveness of several practices in reducing Escherichia coli levels in runoff from fields receiving liquid dairy (Bos taurus) manure. Runoff trials were conducted on replicated hay and silage corn (Zea mays L.) plots using simulated rainfall. Levels of E...

Concentrated sources of dairy manure represent significant water pollution potential. The southern United States may be more vulnerable to water quality problems than some other regions because of climate, typical farm size, and cropping practices. Dairy manure can be an effective source of plant nutrients and large quantities of nutrients can be recycled through forage production, especially w...

The volatilization of NH3 from landapplied manure is not only a loss of valuable N, but also an air quality concern because NH3 plays a role in the formation of airborne particulate matter, which can be a health hazard. The relative differences in potential NH3 losses from land application of liquid dairy manure were determined via 3 methods: surface application, Aerway incorporation (shallow i...

Reducing non-point source phosphorus (P) loss to drinking water reservoirs is a main concern for New York City watershed planners, and modeling of P transport can assist in the evaluation of agricultural effects on nutrient dynamics. A spatially distributed model of total dissolved phosphorus (TDP) loading was developed using raster maps covering a 164-ha dairy farm watershed. Transport of TDP ...

Pilot-scale digesters (850 L) were used to quantify CH4 and H2S production when using forage radish cover crops as a co-digestion feedstock in dairy manure-based digesters. During two trials, triplicate mixed digesters were operated in batch mode with manure-only or radish+manure (27% and 13% radish by wet weight in Trial 1 and 2, respectively). Co-digestion increased CH4 production by 11% and ...

Manure and animal waste deposited on cropland and grazing lands serve as a source of microorganisms, some of which may be pathogenic. These microorganisms are released along with particles of dissolved manure during rainfall events. Relatively little if anything is known about the amounts and sizes of manure particles released during rainfall, that subsequently may serve as carriers, abode, and...