Location: Livestock Nutrient Management Research2011 Annual Report
1a. Objectives (from AD-416)
Long-term goals are to: 1) provide nutritional and management strategies for use by cattle producers to decrease potential adverse effects of feeding operations on the environment without adversely affecting animal performance, 2) quantify and minimize gaseous emissions from feedyards and dairies that may adversely affect the environment, and 3) produce on-farm energy that increases the value of manure and reduces dependence on fossil fuel. We seek to provide science-based information and technologies that can be used by livestock producers, extension specialists, and regulators to best manage feedyard and dairy manure to protect air quality, maintain or improve production efficiency, and improve sustainability of livestock production systems. Over the next 5 years we will focus on: Obj. 1. Develop feeding strategies that optimize utilization of energy, nitrogen, and phosphorus contained in beef cattle diets formulated with and without byproducts such as distiller's grain, in order to minimize excretion in manure. 1A. Measure effects of finishing diet composition on nitrogen and phosphorus excretion, nitrogen volatilization losses, and manure composition of finishing beef cattle in feeding trials. 1B. Measure effects of finishing diet composition on energy excretion, enteric methane losses, and energy metabolism of finishing beef cattle using respiration ca1orimetry. 1C. Determine relative degradable intake protein (DIP)/non-protein-nitrogen (NPN) value of distiller's solubles compared to urea. Obj. 2. Develop methods to quantify, and management strategies to minimize, the generation of greenhouse gases and other atmospheric emissions from feedyards and dairies. 2A. Monitor emissions of ammonia and greenhouse gases from beef cattle feedyards and dairies in the southern Great Plains. 2B. Quantify physical and chemical processes controlling and regulating ammonia and greenhouse gas emissions from feedyard and dairy pen surfaces, retention ponds, lagoons. 2C. Identify, verify, validate process-based models of ammonia and greenhouse gas emissions for beef cattle feedyards and dairies. 2D. Determine effects of pen surface amendments on ammonia emissions from feedyard and dairy pen surfaces, retention ponds, lagoons. 2E. Determine methane production potential of manure from cattle fed steam-flaked corn and distiller's grains based diets. Obj. 3. Isolate, identify, and characterize microbial strains and consortia that are capable of efficiently producing hydrogen and/or electricity from feedyard manures while also reducing pathogen loads. 3A. Identify microorganisms that are electricigens or microbial consortia that can act as electricigens that are present in either beef or dairy confined animal feeding operations. 3B. Determine potential power output of identified electricigens-microbial consortia in low- and high-power fuel cells using various types and forms of manure fuels. 3C. Evaluate microbial consortia-bioreactor designs for efficient generation of hydrogen from manure wastes. 3D. Evaluate influence of various methods of processing manure wastes for use as fuel sources on survival of zoonotic agents, antibiotic resistant gene complexes.
1b. Approach (from AD-416)
Experimental objectives are accomplished through a combination of cooperative,multidisciplinary studies that extend from basic laboratory-scale experiments to practical field experiments. Lab-scale and research feedlot-scale studies are used to determine how chemical, physical and dietary factors affect nutrient losses and atmospheric emissions and for initial evaluation of potential abatement measures. Larger field studies will be used to determine the atmospheric losses under practical conditions in the Southern Great Plains of the United States. Laboratory-scale studies will examine the feasibility of producing electricity with microbial fuel cells that use feedlot and/or dairy manures as sources of fuel and microbes.
3. Progress Report
Cooperative cattle feeding studies were conducted at 3 universities, and samples of diets, feces, and manure were collected. These samples, along with samples from cooperating feedyards and earlier cooperative feeding studies, are being analyzed for dry matter, nitrogen, phosphorus, carbon, and acid insoluble ash so that nutrient excretion and volatilization losses can be determined/estimated. Two respiration calorimetry studies were conducted to evaluate the effects of corn processing method and wet distiller's grain (WDG) on energy utilization and enteric methane emissions from cattle fed corn-based finishing diets. Enteric methane emissions were less and energy retention was greater with diets based on steam-flaked corn (SFC) than diets based on dry-rolled corn (DRC). Replacing corn with 30% WDG did not affect enteric methane emissions or energy retention. Under the conditions of this experiment, the net energy values of WDG were similar to SFC. Long-term monitoring of ammonia and methane emissions at 2 beef cattle feedyards continued for a 5th year. Databases for methane emissions in 2009 and 2010 were built and data processing using the inverse dispersion model completed. Research conducted at a New Mexico dairy focused on ammonia and methane emissions and was presented at the Greenhouse Gases in Animal Agriculture Conference, Banff, Canada, and published in a special issue of the Journal of Animal Feeding Science and Technology. These results were presented to milk producers, industry groups, and researchers at the Western States Dairy Air Quality Symposium, Sacramento, CA. An eddy covariance system that measures methane and carbon dioxide fluxes was acquired, personnel trained, and the system tested and deployed at a shortgrass steppe site. Participation in seminal meetings of National Program Leaders and ARS scientists studying gaseous emissions from animal agriculture led to the creation of Animal GRACEnet. In response to a data request, Animal GRACEnet submitted to USEPA a packet of scientific information, to which we contributed extensive databases on ammonia emissions, scientific journal publications and data summaries. A new research program is targeted at developing uses of animal manure as a feedstock for energy production for onsite usage. The beef cattle animal feeding operation was evaluated for the potential to produce 2 forms of energy: electricity via the use of various types of microbial fuel cells (MFC) and the generation of hydrogen from microorganisms belonging to anoxygenic pigmented bacteria. We were able to recover microbial consortia capable of generating low levels of power in a sediment MFC, whereas a single cell MFC generated several fold greater power in a much shorter period of time. Use of a single cell MFC design will also allow for batch and continuous operations, thus facilitating the cleanup and recovery of agricultural waste water. We were able to recover nearly 600 microbial strains potentially capable of producing hydrogen. Approximately 70 of these isolates were genetically characterized, and 3 of the genera are capable of generating hydrogen gas by 2 different mechanisms.
1. Net energy values of wet distiller's grains. The use of wet distiller's grains, a byproduct of the grain-based bioethanol industry, in beef cattle finishing diets has increased exponentially in the past few years; however, the true net energy values have not been determined. Using a respiration calorimetry system, ARS researchers at the Conservation and Production Research Laboratory, Bushland, TX, determined that the net energy for maintenance and net energy for gain values of wet distiller's grains were similar to that of steam-flaked corn. In addition when the diets were formulated to be equal in total fat content, feeding wet distiller's grains did not affect enteric production of the greenhouse gas methane. These net energy values can be used by nutritionists to better formulate and balance finishing diets and to better predict animal performance.
2. Seasonal and annual ammonia emissions from southern High Plains beef cattle feedyards. Ammonia that escapes as a gas from beef cattle feedyards is a loss of valuable fertilizer nitrogen and can negatively impact sensitive ecosystems and degrade air quality. However the quantity of ammonia emitted from feedyards, and the factors controlling those losses, is not clear. ARS researchers from the Conservation and Production Research Laboratory, Bushland, TX, in collaboration with researchers at West Texas A&M University and Texas AgriLife Research, addressed this need by continuously measuring ammonia emissions from two feedyards over a two-year period. The major factors affecting ammonia emissions were ambient temperature and dietary crude protein concentration. Averaged over the two years of the study, 52% to 59% of fed nitrogen was lost as ammonia at the two feedyards. These results are the most extensive measures of ammonia emission from feedlots available, and they provide an important database that can be used by scientists to validate and verify process models of emissions, provide the cattle industry with accurate science-based ammonia emissions data to meet regulatory requirements, and give regulators more accurate, comprehensive data from which to build ammonia emissions inventories.
3. Methane emissions from Southern High Plains dairy wastewater lagoons in the summer. Methane is a powerful greenhouse gas that may contribute to global climate change. A major source of methane at dairies may be wastewater lagoons; however, the contributions of methane from dairy lagoons in the southern High Plains have not been quantified. Scientists at the ARS Conservation and Production Research Laboratory, Bushland, TX, teamed with researchers at Texas AgriLife Research, West Texas A&M University, and New Mexico State University to conduct an intensive and comprehensive study at a 3,500-cow dairy that included measuring methane emission from lagoons. Daily release of methane from the lagoons averaged 402 kilograms per hectare, or 210 grams of methane released for each cow in the dairy. These results show that uncovered wastewater lagoons can be a significant source of methane at dairies, and also offer producers a potential management method to reduce methane losses.
4. Ammonia emissions from dairy farms and beef feedlots: A review. Ammonia is a gas composed of nitrogen and hydrogen; thus, ammonia emissions from cattle feedlots and dairies are a significant loss of potential fertilizer nitrogen from animal feeding operations, and a source of potential environmental problems. A group of experts in the field of ammonia emissions, including scientists at the ARS Conservation and Production Research Laboratory, Bushland, TX, and other ARS and university scientists, collaborated to produce a comprehensive review that focused on ammonia chemistry, physics, animal interactions, measurement methodologies, emission sources and magnitudes, and modeling of emissions. This big-picture approach was published as an invited review article in the Canadian Journal of Animal Science and gives scientists, regulators, action agencies, and policy makers state-of-the-science knowledge to help understand the factors that control and contribute to ammonia emissions and how they may be controlled.
5. Single cell microbial fuel cell (MFC) design evaluation. Knowledge of efficient MFC designs for selection of microbial consortia and strains along with useful levels of power generation is lacking for beef cattle feeding operations. An ARS researcher at the Conservation and Production Research Laboratory, Bushland, TX, used a single cell MFC design to evaluate the potential for electrical power generation using feedlot retention pond sediment as a fuel source. Electrical power production was greater in the single cell MFC design than in a sediment MFC (at least four-fold greater). Single cell MFC designs appeared to be efficient at selecting for microbial consortia capable of generating electrical power from the feedlot waste stream. Single cell MFC may also provide a useful platform to evaluate various electrode materials, various manure based feed-stocks, and various methods of operation (i.e., batch- versus continuous-flow methods).
6. Isolation of purple nonsulfur bacteria (PNSB) for the production of hydrogen. Hydrogen is a potential renewable energy that can be produced from waste and other byproducts. The PNSB appear to be composed of a genetically diverse set of microorganisms capable of producing hydrogen; however, information regarding the occurrence and genetic diversity of PNSB in manure and retention ponds at beef cattle feedlots is unknown. An ARS researcher at the Conservation and Production Research Laboratory, Bushland, TX, used two microbial growth media types to isolate nearly 600 microbial strains that varied in color and their ability to produce hydrogen from two different beef cattle feedlots. Using selections of these microbial strains, it may be possible to generate hydrogen from dried feedlot manure.
Purdy, C.W., Rice, W.C., Clark, R.N., Straus, D.C. 2010. Influence of feedyards on bioaerosols of two small towns on the Southern High Plains. Texas Journal of Science. 62(2):83-110.