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.
1. Temperature and feed protein levels can predict ammonia loss from feedyards. Ammonia emissions from feedyards are a loss of valuable fertilizer nitrogen, and can potentially have adverse effects on the environment. Feedyard managers need tools to predict ammonia losses to meet reporting regulations and to make management decisions that affect ammonia loss. Scientists at the USDA-ARS Conservation and Production Research Laboratory, Bushland, Texas, used a unique comprehensive two-year database of ammonia emissions from two West Texas beef feedyards to describe the relationship between ammonia loss, temperature, and diet crude protein. They found a strong relationship between temperature and ammonia loss, because many chemical processes that lead to ammonia loss are controlled by temperature. The relationship was described with a simple equation that can be used to predict ammonia losses at Southern High Plains feedyards. Ammonia loss is predicted even more accurately if dietary crude protein concentration is included in the equation. Managers and consultants of southern High Plains feedyards can use these equations to predict ammonia loss and meet regulatory requirements until more widely applicable models of ammonia loss are available.
2. Models predict nitrogen excretion by beef cattle. Reliable estimates of nitrogen excretion in the urine and feces of beef cattle are important to determine how much nitrogen is lost from feedyards as ammonia gas. Researchers at the ARS Conservation and Production Research Laboratory in Bushland, Texas, analyzed 50 different beef cattle diets to determine the relationships between nitrogen intake, the amount of protein in the diet, and nitrogen excretion in the urine and feces of beef cattle. Then, statistical models were developed that predict excretion of urinary and fecal nitrogen by beef cattle. These simple and robust statistical models were very accurate and provide a simple tool to predict nitrogen excretion for a wide range of dietary and animal characteristics. They could be incorporated into more complicated process-based models, which track ammonia production based on numerous animal management and environmental factors, to improve their accuracy for predicting feedyard ammonia loss.
3. Models predict ammonia emissions from beef cattle feedyards. Many processes are driven by environmental and management factors for beef feedyards, two of the most important are air temperature and the amount of protein fed to the cattle. Statistical and process-based models have been developed to estimate ammonia emissions from dairy barns and other enclosed livestock production systems. Little work has been done to determine their accuracy for large, open-lot beef cattle feedyards, which are inherently vulnerable to changing environmental conditions than enclosed barns. Collaborators at the ARS Pasture Systems Management and Watershed Research Unit in University Park, Pennsylvania, and at the University of New Hampshire, ARS scientists at the CPRL in Bushland, Texas, validated two process-based models for predicting emissions from open-lot feedyards. This was achieved by comparing two years of measured ammonia emissions taken from commercial feedyards in the Texas Panhandle with predictions made by Manure-DNDC and the Integrated Farm System Model (IFSM). Modifications to IFSM were necessary for the model to adequately predict ammonia emissions. Both models slightly overestimated ammonia emissions, their prediction accuracy was a significant improvement over estimates made by the constant emission factor for beef cattle that is currently in use by regulatory agencies in the United States. Predictions made by Manure-DNDC and the modified IFSM were sensitive to variations in air temperature and dietary protein concentration, similar to the measured ammonia emissions. Results indicate that both Manure-DNDC and IFSM can assist with ammonia emissions reporting for commercial beef cattle feedyards and provide accurate information for legislators and policy-makers. Process-based models can also help evaluate how specific management practices influence feedyard nutrient balances.
4. Effects of corn processing method and distiller's grain on methane production from beef cattle. Methane is an important greenhouse gas. The composition of the diet fed to cattle can potentially affect the quantity of methane produced in their digestive tract (i.e., enteric methane). Corn in most cattle finishing diets is processed by dry-rolling (minimal process) or steam-flaking (extensively processed). The effects of corn processing method used and the concentration of wet distiller's grains (a by-product of the grain-based bioethanol industry), in the diet on enteric methane production of beef cattle fed finishing diets is not known. Using a respiration calorimetry system, ARS scientists at the Conservation and Production Research Laboratory, Bushland, Texas, determined that the enteric methane production of cattle fed steam flaked corn-based diets was approximately 25% lower than cattle fed dry-rolled corn-based diets. When dietary fat concentrations were similar, replacing corn and fat with wet distiller's grain did not affect enteric methane production; however, when distiller's grains were more than 30% of the diet dry matter, enteric methane emissions increased 20 to 30%. These results can be used to help estimate enteric methane emissions from feedyards (for inventory, regulator or carbon-credit purposes)and to decrease enteric methane production from feedlots.
5. Methane and ammonia loss from dairy lagoons. Dairies are a growing industry in the Southern High Plains and are sources of environmentally important gases such as methane and ammonia. However, the amounts of ammonia and methane emitted from typical High Plains dairies have not been determined. Scientists at the ARS Conservation and Production Research Laboratory, Bushland, Texas, teamed with researchers at Texas A&M AgriLife Research, West Texas A&M University, and New Mexico State University to study emissions from the lagoons that collect dairy wastewater at a 3,500-cow dairy. Ammonia loss from the lagoons was low (from 14 to 30 grams per cow daily, or less than 5% of the nitrogen fed) compared with losses typically measured from the pen area. However, the open, uncovered lagoons were a significant source of methane, ranging from 208 to 359 grams of methane per cow daily. Understanding the quantity and sources of atmospheric emissions can help dairy managers more effectively adopt and apply measures to reduce emissions.
6. Corn processing and distiller's grain effects on production of odors from feedlot manure. The compositon of diets fed to finishing cattle can have significant effects on odors emitted from feedlits. The effects of feeding steam-flaked corn and wet distiller's grains, a by-product of the grain-based bioethanol industry, on odor production from beef cattle fed high-concentrate finishing diets is not known. ARS scientists at the Conservation and Production Research Laboratory, Bushland, Texas, collected feces and urine from steers fed varying diets, and ARS scientists at the Meat Animal Research Center, Clay Center, Nebraska, incubated the feces and urine in chambers in order to measure the production of volatile fatty acids, methane, total gas, and other volatile organic compounds that contribute to feedlot odor. Cattle fed diets containing dry rolled corn excreted more starch than cattle fed steam-flaked corn based diets. Production of odors, volatile fatty acids, and other gases increased as the starch content of the feces increased. Production of sulfur-containing odorous compounds was greater from feces of cattle fed diets containing distiller's grains. These results indicate that odors from feedyards may be decreased by steam flaking corn and by limiting the quantity of distiller's grain in the diet.
7. Corn processing and distiller's grain effects on beef cattle performance and ammonia emissions. The effects of corn processing method (steamflaked or dry-rolled and the feeding of wet distiller's grains, a by-product of the grain based bioethanol industry, on growth performance of finishing beef cattle fed high-concentrate finishing diets and on ammonia emissions from feedyards need to be elucidated. With state collaborators, ARS scientists at the Conservation and Production Research Laboratory, Bushland, Texas, fed beef heifers steam-flaked corn or dry-rolled corn-based diets containing 20% wet distiller's grains. Corn processing did not affect average daily gain, but cattle fed steam-flaked corn required less feed per kilogram of weight gain than cattle fed dry rolled corn. Feeding dry rolled corn-based diets decreased potential ammonia losses, probably because of lower manure pH; whereas, feeding distiller's grains increased N volatilization losses because of greater nitrogen intake. These results may prove to be important in developing models that determine how dietary factors affect ammonia emissions from feedyards.
8. Beef feedyard manure traps ammonium in the short term but may not reduce ammonia emissions in the long term. Ammonia emissions from beef cattle feedyards represent a loss of agronomically important nitrogen, and can potentially affect the environment. Ammonium that is attached to soil or manure solids in feedyard pens is not lost as ammonia gas; therefore, ammonium retention may be an important factor for regulating ammonia losses. However, there is no information available about how much ammonium that beef manure can retain, and for how long. ARS researchers at the Conservation and Production Research Laboratory in Bushland, Texas, revealed that feedyard manures could rapidly remove significant quantities of ammonium from solution; however, nearly all of the retained ammonium was easily removed and most was lost as ammonia gas when manures were dried. These results indicate that ammonium retention by manure in feedyard pens may temporarily reduce ammonia gas volatilization, but it is not likely to influence longer-term feedlot nitrogen balances or ammonia emissions.
9. High carbon in organic dairy manures may reduce plant available phosphorus in soils. Organic dairy production is increasing in the Northeastern U.S. because of consumer demand. Due to different management and feeding practices, some properties of the manure from certified organic dairies are different from conventional dairy manure. This means that when organic dairy manure is used as fertilizer, soil fertility and nutrient cycling may not be the same as is typically observed with conventional dairy manure. ARS scientists from Bushland, Texas, in collaboration with researchers at Tufts University and at the ARS Southern Regional Research Laboratory in New Orleans, Louisiana, looked at the effects of organic dairy manure on soil properties and plant growth in a greenhouse study, where sorghum-sudangrass was fertilized with manures from 13 organic dairies in Maine, inorganic fertilizer, or conventional dairy manure. They found that sudangrass growth was not different when plants were given organic or conventional dairy manures, or chemical fertilizer. The addition of both organic and conventional dairy manure increased the activities of important enzymes involved in phosphorus cycling. However, the amount of phosphorus that was available to plants was negatively related to the carbon content of the manures. This study showed that soil phosphorus cycling and phosphorus availability to plants decreased when fertilized with manure that contained high ratios of carbon-to-nitrogen and carbon-to-phosphorus. Organic dairies use wood shavings and other organic bedding materials, and feed diets containing more forage than conventional dairies. These practices result in manure with high carbon content. Therefore, the carbon content of organic dairy manure needs to be considered when evaluating its fertilizer value because of potential negative effects on available soil phosphorus.
10. Effects of growing conditions on microbial consortia in Microbial Fuel Cells (MFC). It may be possible for feedyards and dairies to produce a portion of their own electrical needs by using manure as a feedstock in MFC. An ARS scientist with the Conservation and Production Research Laboratory in Bushland, Texas, compared the electrical power output of MFC inoculated with different combinations of bacteria that produce electricity (electricigens). At the termination of the experiment, microorganisms on the electrodes of the MFC were harvested and subdivided for genetic analysis and culture isolations. The type of media used (ATCC #1957, Biebl-Pfennig) and the dark/light cycle affected the electricigens that developed on the electrodes. These results may be important in developing MFC that can economically produce electricity from manures.
11. Influence of ammonia on hydrogen production by purple non sulfur bacteria (PNSB). Dissolved ammonia in the growth media inhibits the hydrogen production of microbes by favoring other metabolic pathways. Discovery of a PNSB that can produce hydrogen in the presence of high levels of dissolved ammonia would be an important precursor to development of large-scale bio-hydrogen production systems capable of using un-treated feedyard waste water that is naturally high in ammonia content. Twenty PNSB specimens were selected from earlier studies based on their high hydrogen production rates and were tested using Biebl-Pfennig modified broth with varying concentrations of ammonium chloride (0 to 3.74 millimoles). Only one specimen produced a significant amount of hydrogen at the highest ammonia concentration. This indicates that it will be difficult to identify and isolate PNSB that can produce appreciable amounts of hydrogen from feedlot and dairy waste that contain high concentrations of nitrogen.
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.