Location: Livestock Nutrient Management Research2012 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:
New methods to measure greenhouse gas emissions from pasture-based and feedlot–based beef cattle production systems were developed. Eddy covariance systems that can directly measure methane and carbon dioxide were deployed and tested at a shortgrass prairie site. These systems and open path lasers will be deployed at a commercial feedyard to measure enteric- and manure-based methane emissions. A series of studies were conducted to develop and(or) modify empirical and process-based models of ammonia emission from feedyards. A large database of ammonia emissions was used to develop regression equations that predict ammonia emissions using environmental temperature and dietary crude protein concentration. To better understand processes that control ammonia emissions, ammonium sorption by feedyard manure was quantified. Although beef manure can sorb significant quantities of ammonium, sorbed ammonium is easily removed by other cations and by drying. Two process-based models, Manure-DNDC and the Integrated Farm System Model (IFSM), were evaluated for their ability to predict ammonia emissions from feedyards. Model predictions agreed well with emissions measured at commercial feedyards. A meta-analysis was conducted to develop empirical models to predict urinary and fecal nitrogen excretion by finishing cattle as a function of nitrogen intake and dietary protein concentration. These equations and models can be used by producers, consultants, and policy makers to improve estimates of ammonia losses and to evaluate mitigation strategies. Methane emissions from a commercial feedyard were estimated using micrometeorology techniques. Methane emission rates agreed with values in the literature, and demonstrated that cattle fed high-concentrate finishing diets tend to have lower methane emissions than cattle that consume forage-based diets. Compared with measurement of ammonia emissions, methane monitoring presented several challenges that reduced acquisition of high-quality data. Cooperative cattle feeding studies were conducted, and samples of diets, feces, and manure were collected and analyzed for nitrogen, phosphorus, carbon, and acid insoluble ash in order to calculate nutrient excretion and volatilization losses. Two respiration calorimetry studies were conducted to evaluate the effects of corn processing method and wet distiller's grain on energy utilization and enteric methane emissions from cattle fed corn-based finishing diets. Methane and ammonia emissions were measured at a 3,500-cow open-lot dairy during two intensive summer field campaigns. Open lagoons were a significant source of methane emitted from this dairy. Thus, lagoons could be a significant control point for emissions. Ammonia loss from lagoons represents less than 5% of the nitrogen fed to cows. Studies were conducted to use animal manure as a feedstock for the production of electricity using microbial fuel cells (MFC) and for generation of hydrogen using anoxygenic pigmented bacteria. We recovered numerous microbial consortia capable of generating electricity in MFC and nearly 600 microbial strains potentially capable of producing hydrogen.
Rice, W.C., Galyean, M., Cox, S., Dowd, S.E., Cole, N.A. 2012. Influence of wet distillers grains diets on beef cattle fecal bacterial community structure. BMC Microbiology. 12:25.