In 2014, all man-made sources of greenhouse gas (GHG) emissions in the U.S. were estimated to be 6,870.5 MMT CO2e (millions of metric tons carbon dioxide equivalent). Agriculture was estimated to be responsible 8.3% of those emissions (573.6 MMT CO2e per year). When looking specifically at animal agriculture, all different species together emit an estimated 243.4 MMT CO2e/year, which is 3.5% of all U.S. emissions. The pork industry is estimated to have emitted 26.6 MMT CO2e or 0.34%. (Source: US EPA Greenhouse Gas Inventory 2015)
The two areas where the swine industry produced measurable contributions to agricultural emissions include:
Enteric fermentation – the release of gases during normal digestion by animals. Pigs release approximately 2.4 MMT CO2e of the of the 164.3 MMT CO2e produced by all livestock and poultry in the U.S.
Manure management – pig farms are estimated to release 24.2 MMT CO2e of the 78.7 MMT CO2e produced by all animal manure systems in 2014.
Manure management is planned using a total system approach. Animal manure management systems involve six basic functions: production, collection, transfer, storage, treatment and utilization. The first five out of those six make up the manure management number above. Utilization (usually by land application to crop fields) is instead categorized within “Agricultural soil management”. The greenhouse gases emitted from manure systems include methane and nitrous oxide which form as manure decomposes.
When all of the GHGs emitted during a particular activity or process are added together, it is the carbon footprint. The standardized procedure to calculate carbon footprints is a life cycle analysis or LCA.
Authors: Jill Heemstra, University of Nebraska-Lincoln and Rick Fields, University of Arkansas
This information is part of the program “Integrated Resource Management Tool to Mitigate the Carbon Footprint of Swine Produced In the U.S.,” and is supported by Agriculture and Food Research Initiative Competitive Grant no. 2011-68002-30208 from the USDA National Institute of Food and Agriculture. Project website.
The materials on this page are an interactive lab designed to introduce students (high school level) to pig farming and the connections between management decisions and the greenhouse gas emissions. It also includes information on the economic implications of those decisions. Background information and activities are provided in a graphical (visual) format. Part one can be a stand-alone activity or prepare students for part two.
You can download each of the files individually using the links below or download the entire lab (134 pages – PDF format). The information contains references to Arkansas agriculture and swine production in some areas, but the information is still applicable in other states.
What do you know about swine and greenhouse gases?
This one page (PDF format) fact sheet (including a fun short quiz) can be utilized as part of this lab or as a stand-alone handout to stimulate discussion. Download factsheet
Part One Activity – The Basics
This section includes five files that introduce the basic concepts of greenhouse gases, swine production systems, and glossary of swine production terms. This activity utilizes both text and graphical presentation of concepts and emphasizes information comprehension. Download Part One
Resource information – lesson plan and background information. This includes three aspects of swine management systems including feed management, housing management, and manure management.
Farm management system graphics – a visual aid to depict how each individual practice/component contributes to the building of a given pig farm system.
Farm flashcards – brief description and graphical rendering of various swine farm components
Lab report form – several structured questions designed to
Farm management option guide (FMOG)*
*The FMOG also doubles as a scenario key for the completion of Part 2.
Part Two Activity – Challenging
This section provides more in-depth information on swine production systems and greenhouse gases. It provides insight into management obstacles faced by pig farmers in balancing carbon footprints, available resources, producer goals, and legal compliance. This critical-thinking activity is meant to be completed in small groups. Download Part Two
Resource information – lesson plan and background information.
Farm management option guide FMOG
Three scenarios – each covers manure, feed, and housing
Flashcards – including health and feed, housing, manure
Authors: Rick Fields and Karl Vandevender, University of Arkansas. For questions about these materials, contact Rick at email@example.com
This information is part of the program “Integrated Resource Management Tool to Mitigate the Carbon Footprint of Swine Produced In the U.S.,” and is supported by Agriculture and Food Research Initiative Competitive Grant no. 2011-68002-30208 from the USDA National Institute of Food and Agriculture. Project website.
Feeding less crude protein in pig diets can reduce the carbon footprint of that farm, within limits. Pigs require amino acids (the building blocks of protein) and different protein sources contain different amounts of essential amino acids.
Feed manufactures have begun to make feed grade amino acids (AA) which allow nutritionists and farmers to balance a diet more precisely and feed less crude protein. In turn, this reduces the amount excess nitrogen excreted in the manure (protein contains a great deal of nitrogen). Research has shown that less nitrogen in manure leads to less emissions of gas like ammonia and the greenhouse gas nitrous oxide. Nitrous oxide is nearly 300 times more powerful than carbon dioxide in terms of its ability to trap heat in the atmosphere.
Growth and performance of pigs is not negatively affected when the diet is appropriately balanced for nutrient needs. Meat quality is improved when reducing crude protein in pig diets. Bottom line: this is a highly recommended practice for pork producers and many farmers utilize at least one amino acid (lysine is the most common) in their rations already.
For more information:
Research project examining the use of feed grade AA’s to reduce crude protein in swine diets and whether farmers could use more AA’s than is the current industry norm. They concluded that several limiting AAs can be supplemented to reduce crude protein without compromising performance when the economic conditions (especially when the price of soybean meal is high) are favorable to this practice.
Principles of balancing swine diets – gives an expanded discussion on AA and other important aspects related to the challenge of formulating pig diets that are precise (reduce waste and excess nutrients as much as possible) and still support performance and profitability.
Modeling: The overall goal of the modeling effort was to enhance the National Pork Board swine carbon footprint calculator by integration of specific modules for: animal growth and feed ingredient impacts on manure characteristics. The process model output is to be used as input to life cycle assessment (LCA) to evaluate cradle-to-farm-gate environmental impacts of swine production. An economic analysis model incorporated both process based results (live animal weight, feed, fuel, etc.) and LCA results (greenhouse gas, GHG emissions) to model the cost and potential of different options for reducing GHG emissions in swine production. More…
The model development is supported through an experimental research program focused on feed efficiency and manure management. Feed efficiency is affected by the feed composition and animal physiology which is affected by the animal’s health status. Our research addressed both issues with laboratory and full scale feeding trials.
Health Status: In trials, Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection caused significant reductions in feed intake which led to reductions in rates of gain and body weight. The infection also caused a reduction in diet digestibility leading to greater manure nutrient output per unit of feed intake and increased greenhouse gas (GHG) production from the stored manure. The impact on GHG production is particularly striking when the data are expressed as litters of gas per kilogram of body weight gain. The increased gas production combined with reduced rates of gain results in more than a tripling of gas production per unit of gain for all of the gases. Vaccination against PRRSV appeared to offer little benefit in terms of animal performance, manure nutrient output, or gas production from manure. More…
Amino Acid Supplementation: Studies confirmed that crude protein can be replaced with feed grade AA to meet the requirement of the first 5 limiting AA without negatively impacting growth performance or carcass composition when diets are formulated on a NE basis; however, further CP reductions resulted in more variable growth performance.
Manure Management: The gasification system has been successfully operated with an algae feed stock in a series of preliminary, proof-of-concept tests. The algal turf system has been fully constructed and is now operational with samples being taken for nitrogen and bacteria levels. Nutrient retention management technologies for manure will include algal growth for on-farm nitrogen retention using a pilot scale experimental system and thermal conversion to fuel gas and bio-char (a soil amendment).
Extension, Outreach, Undergraduate Research Experiences: A significant component of this project is devoted to non-research activities including developing materials for extension work – disseminating research information to non-technical audiences for integration into existing knowledge and application in farm decision-making. Undergraduate students from several universities were also provided with opportunities to participate in research projects, gaining valuable experience and to train potential future scientists.
The Swine Environmental Footprint Calculator is available from the National Pork Board. It will continue to be updated when applicable research information and data sets are available. Go to the model home page….
Also visit the conference presentations section to find out more about the research findings.
Panel presentation: Burek J, Thoma G, Popp J, et al. Developing Environmental Footprint,Cost, and Nutrient Database of the US Animal Feed Ingredients.
Poster presentation: Burek J, Thoma G, Popp J, et al. Formulating low-cost and low-environmental footprint swine diets.
Midwest Section – American Society of Animal Science
2015 – Comparison of the effects of antibiotic-free and conventional management on growth performance in swine. C. E. Vonderohe*, A. M. Jones, B. T. Richert, J. S. Radcliffe, Purdue University, West Lafayette, IN. Abstract 102, page 47.
2014 – Effect of feeding reduced-CP, amino acid supplemented diets on dietary nitrogen and energy utilization and volatile fatty acid excretion in wean-to-finish swine. A. M. Jones1*, D. T. Kelly1, B. T. Richert1, C. V. Maxwell2, J. S. Radcliffe1,1 Purdue University, West Lafayette, IN, 2 University of Arkansas, Fayetteville. Abstract 037, page 16.
2013 – Effects of amino acid supplementation of reduced crude protein (RCP) diets on performance and carcass composition of growing-finishing swine. J. K. Apple1*, B. E. Bass1, T. C. Tsai1, C.V. Maxwell1, J. W. S. Yancey1, A. N. Young1, M. D. Hanigan2, R.Ulrich3, J. S. Radcliffe4, B. T. Richert4, G. Thoma3, J. S. Popp5,1 Animal Science, University of Arkansas Division of Agriculture, Fayetteville, 2 Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg, 3 Chemical Engineering, University of Arkansas, Fayetteville, 4 Animal Science, Purdue University, West Lafayette, 5 Agricultural Economics & Agribusiness, University of Arkansas Division of Agriculture, Fayetteville. Abstract 0224, page 73.
2013 – Effects of amino acid supplementation of reduced crude protein (RCP) diets on LM quality of growing-finishing swine. A.N. Young1,*, J. K. Apple1, J. W. S. Yancey1, J. J. Hollenbeck1, T. M.Johnson1, B. E. Bass1, T. C. Tsai1, C. V. Maxwell1, M. D. Hanigan2,J. S. Radcliffe3, B. T. Richert3, J. S. Popp4, R. Ulrich5, G. Thoma5,1 Animal Science, University of Arkansas Division of Agriculture, Fayetteville, 2 Dairy Science, Virgina Polytechnic Institute and State University, Blacksburg,3 Animal Science, Purdue University, West Lafayette,4 Agricultural Economics & Agribusiness, University of Arkansas Division of Agriculture,5 Chemical Engineering, University of Arkansas, Fayetteville. Abstract P027, page 97.
2013 – Maximum replacement of CP with synthetic amino acids in nursery pigs. B. E. Bass1, T. Tsai1*, M. D. Hanigan2, J. K.Apple1, R. Ulrich3, J. S. Radcliffe4, B. T. Richert4, G. Thoma3, J.S. Popp5, C. V. Maxwell1,1 Animal Science, University of Arkansas, Fayetteville, 2Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg, 3 Chemical Engineering, University of Arkansas, Fayetteville, 4 Animal Science, Purdue University, West Lafayette, 5 Agriculture Economics & Agribusiness, University of Arkansas, Fayetteville. Abstract P042, page 102.
Sadaka, S., M. Sharara and G. Ubhi. 2014. Performance Assessment of an Allothermal Auger Gasification System for On-Farm Grain Drying. Journal for Sustainable Bioenergy Systems. Vol. 4: 19-32.
Sharara M, Holeman N, Sadaka S, Costello T. 2014. Pyrolysis kinetics of algal consortia grown using swine manure wastewater. Bioresource Technology. 169: 658-666.
Sharara, M. and S. Sadaka. 2014. Thermogravimetric Analysis of Swine Manure Solids Obtained From Farrowing, and Growing-Finishing Farms. Journal for Sustainable Bioenergy Systems. Vol. 4: 75-86.
Project Director: Greg Thoma firstname.lastname@example.org, Co-Project Director: Marty Matlock email@example.com
Principle Investigators: Richard Ulrich, Jennie Popp, Charles Maxwell, Thomas Costello, Scott Radcliffe, Mark Hanigan, Brian Richert, Karl VanDevender, Sammy Sadaka, Chengsheng Li, William Salas
Dr. Karl VanDevender – University of Arkansas:Cooperative Extension Service and Dr. Brian Richert – Purdue University
The research and modeling work encompassed by this project offers great potential for assisting researchers, policy makers, and especially farm managers to make informed management and facilities decisions regarding GHG emissions while maintaining production and profitability. However for this potential to be realized the swine production community needs to be aware of both its abilities and availability. To this end existing relationships with the National Pork Board , U.S. Pork Center of Excellence, and eXtension are being enhanced.
The focus audience of this training is technical service providers (professionals, consultants, engineers, nutritionists, extension swine specialist and educators) who are involved in assisting swine producer’s making both strategic and tactical management decisions. The goal is to develop and implement education and outreach programs focused on the interaction between climate and swine science.
Dr. Richert serves as the nutrition domain editor for the US Pork Center of Excellence and US Pork Information Gateway which also serves as the swine domain for National eXtension. Through this relationship with domain editor for the Environmental section, Erin Cortus, we have initiated the rewriting of the factsheet “Pork production and greenhouse gas emissions” and have started authoring a factsheet on “Pork production, what might your carbon footprint be?”
Karl VanDevender, the project liaison with eXtension has a long history with the Livestock and Poultry Environmental Learning Center (LPELC) which has become the eXtension community of practice working in the area of livestock and poultry manure management. In response to the project needs he has transitioned from a topic area leadership role to a member of the LPELC leadership team, alongside other eXtension professionals. This provides the capacity to ensure that the project and LPELC take full advantage of the synergy of multiple funded projects without undesirable duplication of effort and resources.
The benefits of integration of extension efforts with research and education is that more rapid translation of research results into actionable knowledge will be achieved. Frequent team meetings are established to ensure that there is continual interaction and information exchange.
The working relationship between our project’s Extension component and the LPELC has helped facilitate the recent production of the webcast “Life Cycle Assesment Modeling for the Pork Industry“, which overviews the LCA goals and provides details in the sub-project areas dealing with concepts and research of feed management. Our project will also be hosting a special session featuring project leads during the LPELC hosted Waste to Worth: Spreading Science and Solutions conference in Denver Colorado, April 2013. The special session will feature a showcasing of the project’s individual and collective works; topics discussed will include: LCA concepts, research and modeling challenges, model results, and economics.
Dr. VanDevender recently published an article in PIG Progress Magazine entitled “A Swine Carbon Footprint Model as a decision aid tool”, in which the efforts of this project were presented. The article stressed the imoportance of continued management of greenhouse gasses in the livestock industry through improvements in efficiencies.
Developing the necessary system and protocols for sharing and vetting information and educational materials
Strengthening the relationship between this project and eXtension
Development and delivery of information both internally and externally.
Dr. Marty Matlock and Dr. Jennie Popp – University of Arkansas
A summer research program for undergraduate students has been developed with the focus of carbon footprint mitigation from agriculture. The goal of this USDA REU is to support 10 students each summer for a 10 week period throughout the duration of this project. The REU supported by this project is offered parallel to the National Science Foundation Research Experience for Undergraduates (NSF REU), and students are recruited from the same pool as the NSF REU programs. The REU students are selected through an application process informed by an established recruitment network. We are actively recruiting from under-represented minorities, including: Native Americans, African Americans and Hispanics.
REU Students spend the first week in a skills development workshop where they learn to develop and test hypotheses, analyze data and write reports and manuscripts. They then spend eight weeks working with their faculty mentors, followed by a one week report of results in poster and presentation format.
The expected outcomes of the REU include; inspiring students to continue their education through graduate school, and fostering an interest and competency in agricultural research.
To expose undergraduate students to the scientific research process through the steps of developing testable hypotheses, data collection and analysis, and scientific communication in the form of oral presentations and written manuscripts.
Dr. Marty Matlock and Dr. Thomas Costello – University of Arkansas
Algal biomass offers many advantages over traditional energy crops; algal biomass generates higher yields and requires smaller land area than other energy crops. In addition to biomass production for potential biofuel feedstock generation, algal growth systems can also act as tertiary treatment systems for wastewater. Algal growth can dramatically reduce nitrogen and phosphorus from wastewater. Unlike conventional open pond and photo-bioreactor systems, periphytic systems (e.g., algal turf scrubbers) generally involve the polyculture of micro-algae, which does not require specialized conditions. While algal turf scrubber systems are traditionally used for water treatment, they are also capable of generating high biomass yields.
The Algal Nutrient Removal Team has focused on installation of the test bed for the research. This has included construction of a precision graded base for the 20-ft wide by 200-ft long flow way. Our working hypothesis is that operation of an algal flow-way to treat swine manure will remove nutrients, produce a harvestable biomass residue, and add dissolved oxygen which will decrease potential for nitrous oxide emissions (and possibly methane emissions) during manure storage. Wastewater from the swine finisher unit at the University of Arkansas will provide nutrient input to the Algae Flow-way. The flow way will be tested with manure output from pigs fed conventional diets as well as the custom rations intended to reduce manure nitrogen. Impacts on nutrient removal and algal biomass productivity, as a function of diet formulation, will be measured. Nutrient removal will be documented and data collected will be used in the DNDC model to represent the waste treatment performance of the algal systems
Algal growth systems not only provide a method for nutrient removal from animal waste, but also provide biomass production as feedstock for biofuels which can improve the carbon footprint of swine production and other animal production systems in the U.S. This project will provide field scalable data on life cycle impacts of the technology. Design and construct algal turf scrubber concluded in late summer of 2012, and the system is currently undergoing callibrations in preperation for full-scale trials.
Measure algal productivity.
Quantify impact of algal nitrogen uptake on swine system GHG emissions.
Dr. Karl VanDevender – University of Arkansas. Cooperative Extension Service
Many technologies being considered incorporate some type of manure separation to concentrate manure solids, nutrients, and energy content. An LCA study in Denmark showed that energy recovery (incineration, gasification, and anaerobic digestion) had lower GHG emissions than traditional land application of swine manure. Other studies point to the complexities of manure management system design options in relation to GHG emissions. This portion of the project will quantify the effect of various solid separation approaches on the chemical composition of the manure generated by the feed trials at the University of Arkansas facilities during this project ,and generate the necessary manure solids for the thermo-chemical conversion portion of this project. Design and construct a pilot scale mobile solids separation system (see image below) is currently approaching completion and anticipated to be ready to begin trial calibrations soon.
Capture and separation of manure from the UA animal experiments.
This unit contains systems to allow for various combinations of mechanical screen and filter bag separation, with and without chemical treatment; and is designed to operate in a batch mode with a capacity of 1000 gallons per batch.
Determine overall characteristics for the feed trial manure samples to provide additional validation data for the animal physiology sub-model.
Dr. Sammy Sadaka – University of Arkansas. Cooperative Extension Service
Due to the high moisture content, it is not economical to transport raw swine manure over long distances. As a result, manure is spread on land close to the source at high application rates. The energy content of dry manure is in the range of 12 to 18 GJ/ton, about half that of coal. In recent years, wet and dry gasification of algal biomass has been investigated by several researchers. Fluidized bed and downdraft gasification of algal biomass showed various challenges due to the nature of algae biomass. An auger gasification system (see image below) developed in the University of Arkansas, Bioenergy Laboratory, may help to simplify the air gasification process for this type of biomass. Algal biomass was gasified using the auger system during preliminary tests. Several improvements to the system took place during the first year to ensure smooth operation. Our long-term goal is to provide technology to convert swine manure and/or algal biomass to biofuel via a continuous gasification process. Energy conversion technology could provide a revenue stream of about $23 billion/year to the livestock industry.
Modify the existing gasification unit to handle swine manure and/or algal biomass.
Test the performance of the gasifier
Optimize the operating parameters to maximize producer gas quality.
Study the effect of reactor temperature on the process yields (gas, char, and tar), as well as on the process efficiency.
Dr. Charles Maxwell, Dr. Jennie Popp, and Dr. Richard Ulrich – University of Arkansas; Dr. Scott Radcliffe – Purdue University, and Dr. Mark Hanigan – Virginia Tech
Why study crude protein and carbon footprint?
Maximizing feed grade amino acid (FGAA) use and reducing dietary crude protein in swine diets has been shown to dramatically reduce nitrogen excretion in both nursery and growing/finishing swine which could substantially reduce nitrous oxide (N2O) emissions associated with manure management in swine production. The global warming potential of N2O is about 298 times that of CO2 (carbon dioxide). Reducing the crude protein (CP) content of grower and finisher diets has also been repeatedly shown to enhance carcass quality by elevating intramuscular fat. While some crystalline amino acids are already commonly used in pork production the maximum level of CP reduction, in conjunction with the optimum amino acid inclusion rate, has not been sufficiently determined for widespread acceptance by the swine industry.
Hypothesis: Reducing dietary CP while maintaining amino acids (AA) at equivalent Standardized Ileal Digestibility (SID) ratios by supplementing feed grade AA will reduce nitrogen (N) excretion and greenhouse gas (GHG) emissions (N2O from manure) without impacting swine performance or carcass yield.
Determine the practical limits of reducing CP in diets of nursery and finishing pigs.
Validate the effectiveness of reduced dietary nitrogen as a mitigation strategy for greenhouse gases.
Provide data for validation of animal physiology model capable of predicting swine performance and relevant manure characteristics (quantity and composition for Manure DNDC).
Compare ME vs. NE formulation strategies on lean tissue deposition and fat accretion.
Determine the impact of dietary amino acid levels on signaling in regulation of tissue growth.
[2014 & 2015 annual reports indicated another objective was added] Estimate manure reductions in N excretion via a N balance trial.
Studies were conducted at multiple sites. One was the University of Arkansas wean-to-finish facilities and the second at the Purdue Swine Environmental Research Building (SERB). See the videos above for more on these facilities). The data generated was utilized in modelling work at Virginia Tech. The model was ultimately incorporated into the Swine Environmental Footprint Calculator.
What Did We Do? (Methods or Experimental Design)
To evaluate maximum replacement of CP with FGAA, 320 weaned pigs were allotted to gender-balanced pens in a wean-to-finish facility (8 pigs/pen). Within blocks, pens were randomly assigned to 1 of 5 dietary treatments. Diets were formulated to maintain constant ME and SID Lys across treatments with SID Lys set at 95% requirement (PIC Nutrient Specification Manual, 2011). Diets were formulated to meet the SID AA ratio recommendations for other indispensable AA (SID) for nursery pigs through the 6th limiting AA (PIC Nutrient Specifications Manual, 2011). For each phase, Ctrl diets were devoid of FGAA, whereas Lys HCl was added in equal increments at the expense of CP (SBM, fish meal [FM], and poultry meal [PM] in phase 1, FM and PM in phase 2, and SBM in phase 3). This formulation procedure resulted in diets that were below the His and Phe/Tyr SID requirement for the highest level of CP reduction. CP and Lys inclusion levels were analyzed. Experiment 2
A second three phase nursery study was conducted with pigs weaned at 21 d to further evaluate limits of CP reduction in nursery diets and compare performance in pigs fed diets based on formulation on an ME vs. NE basis. The study involved 7 pigs/pen and 7 replicates/treatment. Dietary ingredients were similar to those used in experiment 1, except soy protein concentrate was used to replace fish meal. Dietary treatments were: 1), Control diet formulated on an ME basis and with FGAA used to meet the “Trp Set Point” without adding feed grade Trp in phase 1 and 2 and 0.02 % added Trp in phase 3; 2) Diet formulated on an ME basis and to meet the “His Set Point” without added feed grade His; 3) As 2 with diets formulated on a NE basis.
Nursery What Did We Learn (Results)?
Pigs fed RCP 1, RCP 2, and RCP 3 diets in phase 1, 2 and 3, and for the overall study had similar ADG and BW but growth performance declined for pigs fed RCP 4 diets (Table 5; Quadratic effect, P < 0.01). A similar response was observed in ADFI in all time periods except phase 1 where ADFI was similar among treatments. In phase 1, G:F ratio followed a similar response (Quadratic effect, P < 0.01), but decreased linearly in phase 2 (P < 0.08), 3, and overall (P < 0.01). It should be noted that the RCP 4 diet was below requirement for SID His:Lys and Phe/Tyr:Lys which might explain the decrease in performance. The results of this study establishes that a high inclusion of feed grade Lys at the expense of intact proteins can be fed without decreasing ADG and ADFI except at the highest level of FGAA where the requirement for all IDAA was not met. However, G:F was generally reduced at the higher inclusion rates of FGAA, particularly in phase 3. Experiment 2
No differences were observed in ADG, ADFI, or G:F (Table 6) in any phase or overall in pigs fed diets formulated on an aggressive FGAA inclusion (His Set Point) based on ME (Trt.2) or NE (Trt. 3) compared to pigs fed AA inclusion levels currently used in swine industry (Trt. 1). These results indicate that in nursery pigs, one should be able to use a His Set Point in formulating AA based diets without concern for pig performance.
The previous nursery experiment (Experiment 1; Bass et al., 2013) conducted to evaluate feeding reduced CP diet with the highest levels of FGAA to nursery pigs resulted in poor growth performance, especially G:F ratio in phase 3 and the overall nursery period. In the previous study, experimental diets were formulated to meet the 95% of SID Lys requirement for nursery pigs. Also, RCP 4, which was formulated with the highest level of FGAA, did not meet the His and Phe requirement Lys/NE.
In conclusion, unlike the previous study, growth performance of nursery pigs was not affected by the higher level of FGAA and lower dietary CP. This may be due to different SID His:Lys and SID Phe+Tyr:Lys ratios used in diet formulation or different protein source used in each study. In the second nursery study, all diets were formulated based on 100 % or excess of SID Lys requirement for nursery pigs, and were formulated to meet the His and Phe+Tyr requirement. In addition, soy protein concentrate (SPC) was used in the second study during phase 1 and 2, replacing menhaden fish meal used in nursery study one.
Each experiment was conducted following a five phase grow-finish protocol. Pigs were fed 1 of 4 or 5 diets and 10 ppm of Paylean was fed during the final 3-week finishing phase-Phase 5. During phase 1 through 5, individual pig BW, and pen feed disappearance were measured over each phase to allow calculation of ADG, ADFI and G:F by phase. Tenth rib, ¾ midline back fat measurements and loin muscle area were estimated at study initiation and at the end of each phase via ultrasound to allow estimation of carcass lean gain. When the average of all blocks was 129-134 kg all pigs were individually weighed, tattooed, transported to, and harvested at a commercial pork packing plant according to industry accepted procedures. Longissimus muscle (LM) and fat depths at the 10th rib were measured on-line with a Fat-O-Meater probe and individual hot carcass weight was recorded. Experiment 1
A total of 420 pigs were blocked within gender and randomly allotted to pens with 6 pigs/pen. Within blocks, pens of pigs were randomly assigned to 1 of 5 dietary treatments (7 reps/treatment/gender). Diets were formulated by incrementally increasing levels of Lys with corresponding reductions in CP. Pigs were randomly allotted to the following diets:
Ctrl: Corn-SBM-DDGS diets devoid of FGAA,
RCP 1 (reduced crude protein 1)
RCP 4 – was balanced on the requirement of the 7th limiting AA, His (PIC Nutrient Specifications Manual, 2011) which was considered the practical limit of the highest level of RCP because of availability constraints.
RCP 1 to 4 were then formulated to have stepwise and equally spaced increased Lys with corresponding reductions in CP between RCP 1 and 4. Diets 2-4 were supplemented with FGAA as needed to meet AA needs based on AA minimum ratios. Dietary CP and Lys inclusion levels were analyzed.
Diets were formulated to 95% of the average SID Lys requirement for barrows and gilts (PIC Nutrient Specifications Manual, 2011), and exceeded the SID AA/Lys ratio recommendations for other IDAA by 2 percentage points.
Distillers dried grains with solubles (DDGS) were included in all diets at the 20% level, with the exception of phase-5 finishing diets which was devoid of DDGS. Experiment 2
In experiment 1, diets were formulated on an ME basis and as soybean meal was reduced in diets, the calculated Lys/NE decreased which may explain some of the increase in fat deposition in pigs fed ME based diets formulated by decreasing soybean meal and including high levels of FGAA. Therefore, experiment 2 was conducted to establish the efficacy of using a “Set Point SID requirement” of sequentially reducing CP by adding FGAA to meet the SID IDAA/Lys ratio as a means of establishing the practical limits of CP reduction and AA replacement without impacting growth performance, carcass composition or quality in growing and finishing pigs fed NE based RCP diets. Diets were formulated starting with a Ctrl diet that approximates acceptable inclusion levels of FGAA currently used in industry, followed by sequentially formulating three additional dietary treatments, each based on the next limiting AA. Diets in this study were formulated on a constant NE basis within phase. DDGS was included in all diets. The SID His requirement in the highest RCP diet was met in each phase without added feed grade His.
There were a total of 9 replicates/treatment with pigs housed 6 pigs/pen. Sex within pen was balanced. Diets were formulated as in experiment 1 which were:
Treatment 1, Ctrl: Conventional phase 1 through 5 diets that approximates acceptable levels of FGAA currently used in industry. The assumption is that most in the industry are comfortable utilizing feed grade Thr and Met to meet the suggested SID Thr/Lys and Met/Lys ratio in diets formulated to meet the SID Trp/Lys requirement without added feed grade Trp. This is referred to as the Trp Set Point.
Treatment 2, RCP 1: Diets were formulated to meet the next limiting AA. In phase 1 and 5, the next limiting AA was Val while Ile was next limiting in phases 2, 3 and 4. This is referred to as the “Val or Ile Set Point”. Note that neither feed grade Val nor Ile were added in any phase.
Treatment 3, RCP 2: Diets were formulated to meet the next limiting AA. In phase 1 and 5, the next limiting AA was Ile while Val was next limiting in phases 2, 3 and 4. This is referred to as the “Val and Ile Set Point”. Note that feed grade Val but not Ile was added in phases 1 and 5, and Ile but not Val was added in phase 2, 3, and 4.
Treatment 4, RCP 3: Diets were formulated to meet the next (7th) limiting AA, His. This is referred to as the “His Set Point”.
All diets were supplemented with FGAA to meet IDAA recommended levels. Note that feed grade His was not added to any diet.
Grow-Finish Studies – What Did We Learn?
Body weights of pigs decreased linearly with decreasing dietary CP during phase 1, 2, and 3 (P < 0.01; Table 7). Additionally, BW increased and then decreased quadratically during phase 3 (P = 0.09), 4 (P < 0.04), and 5 (P < 0.01) with BW decreasing significantly in pigs fed RCP 4. When Paylean was included in the Phase 5 diets, barrows fed the Ctrl diet had greater ADG than Ctrl-fed gilts, but RCP 1-, RCP 2-, and RCP 3-fed gilts had greater ADG than their castrated male counterparts (Quadratic gender × reduced CP diet, P = 0.08; Figure 1A) Both ADG and G:F decreased linearly (P ≤ 0.06) during phase 1 and 2. Furthermore, gain efficiency increased 4.6 % in gilts between Ctrl and RCP 2 before decreasing to similar G:F values between Ctrl and RCP 4; however, G:F remained relatively unchanged in barrows across the 5 dietary treatments (Quadratic gender × reduced CP diet, P = 0.04; Figure 1B).
Across the entire feeding trial, ADG increased only 2 % between Ctrl and RCP3, but dropped 6 % between RCP3 and RCP4 (Quadratic, P < 0.01). On the other hand, ADFI tended to decreased linearly (P = 0.09) as CP was reduced in swine diets. Gain efficiency increased 4.6 % in gilts between Ctrl and RCP2 before decreasing to similar values between Ctrl and RCP4; however, G:F remained relatively unchanged in barrows across the 5 dietary treatments (Quadratic gender × reduced CP diet, P = 0.04; Figure 1C).
Reducing dietary CP and optimizing the use of FGAA had limited (P ≥ 0.21) effects on HCW, dressing percentage, or LM depth; however, 10th rib fat depth increased linearly (P < 0.01), and fat free lean percentage at study termination decreased linearly as CP was reduced in swine diets (P < 0.02; Figure 1D). Experiment 2
Effects of dietary treatment (Trt.) indicated that ADG decreased linearly with increasing dietary FGAA in phase 3 (Table 8, P < 0.05), 4 (P < 0.10), 5 (P < 0.01) and overall (P < 0.01). Similarly, ADFI decreased linearly in phase 4 (P < 0.05), 5 (P < 0.01) and overall (P < 0.01) with increasing FGAA. Compared to pigs fed the control diet (Trt. 1), G:F in phase 1 increased in pigs fed increasing levels of FGAA at the lower inclusion rates (Trt. 2 and 3) before decreasing to the control level at the highest level of inclusion (Trt. 4, Quadratic effect, P < 0.05). During phase 3, a small, but significant, decrease in G:F was observed with increasing levels of FGAA (Linear effect, P < 0.05). For the overall study, however, a trend for increased G:F was observed (Linear effect, P < 0.06). BW increased at the end of phase 2 with increasing level of FGAA (Quadratic effect, P < 0.06). However, consistent with ADG, BW decreased with increasing dietary FGAA at the end of phase 3, 4 and 5 (Linear effect, P < 0.05, P < 0.01 and P < 0.01, respectively).
As might be expected based on BW, HCW decreased with increasing inclusion of dietary FGAA (Linear effect, P < 0.01). Tenth rib backfat was lower in pigs fed diets formulated to the Val or Ile Set Point (Trt. 2) or the His Set Point (Trt. 4) when compared to those fed diets formulated to the Val and Ile Set Point (Trt. 3).
Publications – G/F (Trial 1)
2013 Midwest American Society of Animal Science (ASAS) meeting Abstract 0224, page 73 (performance and carcass composition)
2013 Midwest American Society of Animal Science (ASAS) meeting Abstract P027, page 97 (LM – longissimus muscle quality)
Significance. This information is timely since the cost of soybean meal is approaching record levels which make substitution of synthetic amino acids for intact protein more economically feasible.
Nitrogen (N) Balance Study
What Did We Do? (Methods)
Thirty-two barrows were used to evaluate the effect of feeding reduced CP, AA supplemented diets, on nutrient and VFA excretion. Pigs were randomly allotted to the following diets:
Control: Corn-SBM-DDGS diets with no FGAA,
1X reduction in CP,
2X reduction in CP, and
3X reduction in CP. This diet was balanced on the 7th limiting AA in each phase.
Diets 2 and 3 were formulated to have stepwise and equally spaced reductions in CP between diets 1 and 4. Diets 2-4 were supplemented with FGAA as needed to meet AA needs based on NRC 2012 AA minimum ratios. Four nursery phases and 5 grow-finish phases (21d phases) were fed. Pigs were housed in stainless-steel metabolism pens equipped with a nipple waterer and stainless steel feeder. Collections started with nursery phase 3 and during nursery phases pigs were allowed an eight day adjustment period to the diets followed by a 3 d total collection of feces, urine, and orts. During the grow-finish phases, pigs were acclimated to diets for the first 10 d of each phase, and then feces, urine, and orts were collected for 3 days.
Nitrogen Balance – What Did We Learn? (Results)
Overall, from d 14-147 post-weaning ADFI was linearly increased as dietary CP was reduced, but no effect of dietary CP concentration on ADG or G:F (Table 9) was observed. Fecal excretion (DM) tended to respond in a quadratic (P = 0.08) fashion with decreasing fecal excretion (DM) up to 2X reduction in CP, but then increasing in 3X fed pigs. Both DE and ME (kcal/kg) were linearly (P < 0.01) reduced as dietary CP was reduced. The linear (P < 0.01) decrease in N intake for pigs fed reduced CP diets was accompanied by linear (P < 0.01) decreases in both urinary and total N excreted. Nitrogen digestibility (%) linearly decreased (P < 0.01) and N retention linearly (%) increased (P < 0.01) with reductions in dietary CP. Overall, there was a linear (P < 0.03) reduction in fecal ammonium as dietary CP was reduced. Total carbon (C) intake and total fecal C excreted tended (P = 0.06) to respond quadratically with an increase in both C intake and C excretion up to the 1X reduced CP diets, followed by a decrease in C intake and increasing C excretion to the 3X diet creating a linear (P < 0.05) decrease in C digestibility as dietary CP was reduced.
Significance. The ability to add total fecal and urine collections of the nitrogen manipulation diets across all body weights tested at the University of Arkansas before the diets were tested for greenhouse gas emissions at Purdue University improved the estimation of compounds excreted in fresh manure and then the conversion of these excreted nutrients and compounds during storage in typical deep pit manure structures under the swine facilities (as were measured during the Purdue 12 room study). This research project provided data for a critical link between excretion, storage, and land application.
Validating the Nursery, Grow-Finish, and GHG Measurement Studies
Large-scale trials are in progress to validate the nursery and grow-finish trials done at Arkansas. The Purdue facility is scaled more similarly to a commercial production system. Gas measurement and monitoring, and separate manure handling systems for each room allowed direct measurements with which to compare previous estimations.
Treatment structure for the experiment was:
Conventional diet containing ~ 0.15% Lys-HCl
1X reduction in CP with additional synthetic amino acids
2X reduction in CP with additional synthetic amino acids
All diets were supplemented with Ractopamine during the final 3-4 weeks of the trial, and amino acid concentrations were increased based on estimated increases in lean tissue accretion. However, the overall treatment structure will remain the same. The Experiment involved 24 pens of 10 pigs each per treatment, with 8 manure pits/trt, and 4 rooms per trt. Pen was the experimental unit for all growth performance, feed intake, and carcass data. Pit was the experimental unit for manure excretion data and room is the experimental unit for emission data.
Real-time monitoring of air temperatures included relative humidity, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ammonia (NH3), and hydrogen sulfide (H2S). Total suspended particulates were monitored using gravimetric samplers. The emission and animal performance data were significantly more accurate in this replicated, environmentally-controlled building than is possible commercially, yet still simulate commercial conditions.
Manure from each pit was completely removed to outside storage for volume determination, thorough agitation and sampling at the end of each trial. In addition, core manure samples based on a grid system were obtained at the end of each growth phase. Manure volume in each pit was determined at diet phase changes by taking 6 gridded depth measurements between the slatted floor. Manure samples were analyzed for pH, dry matter, ash, total nitrogen (N), ammonium N, phosphorus (P), carbon (C), and sulfur (S). Data defining the relationship between the reduction in dietary CP with a reduction in manure N and other changes in manure characteristics are essential to model development of the impact of this mitigation strategy on GHG emissions. An additional benefit will be defining the limits of this strategy without impacting animal growth performance under conditions where industry stakeholders have input.
Validation study – What did we learn (results)?
Coming Soon! (first half 2016)
Modeling the Data
[See also: Virginia Tech modeling efforts] Current nutritional requirement models for swine are focused on partitioning of dietary energy and amino acids to maintenance, growth, gestation, and lactation. Little focus is placed on predicting nutrient excretion, and thus these models cannot be used to provide inputs to an emissions model. Models that predict excretion of energy, protein, and phosphorus have been developed, but have not been evaluated for the accuracy of predictions; and evaluations that have been undertaken focus on predictions of growth and body composition, not nutrient excretion.
GHG emissions from manure storage facilities can be predicted from manure composition, underscoring the need for a robust animal model capable of predicting both animal performance and nutrient excretion. Prediction of GHG emissions from swine manure requires knowledge of N and volatile solids content, neither of which are provided by current NRC predictions.
Data from the nitrogen mitigation growth and nitrogen excretion studies were utilized in enhancement of an animal model capable of predicting swine performance and excretion of nitrogen, carbon, and volatile solids (inputs required by the DNDC model). The growth model developed by the workers at UC-Davis and the recently released Nutrient Requirements of Swine (NRC) eleventh revised edition will be used as a starting point for model development. Equations describing the response to dietary protein and amino acid additions will be evaluated for accuracy, and the effects of Paylean on animal performance and manure nutrient output will be encoded and tested for accuracy. This work is scheduled to precede and utilize data from the UA trial and literature sources. The model will be further evaluated in the 5th year using the Purdue data set.
Why Study Health of Pigs In Relation to Greenhouse Gas (GHG) Emissions?
Our working hypothesis is that immune activation, from clinical and subclinical disease, reduces growth performance and concomitantly increases nutrient excretion and subsequent GHG emissions from manure management.
Evaluate impact of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) exposure and vaccination on animal performance, manure output and composition, and greenhouse gas (GHG) emissions from stored manure.
Antibiotics and Antibiotic Alternatives
Evaluate the effects of health status on GHG emissions and carbon and water footprints
Evaluate effects of health status (Salmonella) on animal performance, manure output and composition, and GHG emissions from stored manure.
Research Summary: What Have We Done? What Have We Learned?
Manure reactors installed at Virginia Tech for the pilot study. The manifold on the wall distributes a constant stream of air to each bioreactor, and forces gas through the exhaust lines into the gas analyzers
Thermo Scientific analyzers for carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), mono-nitrogen oxides (NOx), ammonium (NH4), and hydrogen sulfide (H2S). A programmable manifold switch will sample gas from each reactor sequentially throughout the day.
Pigs were randomly assigned to a 2 x 2 factorial design investigating the interaction of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) vaccination (with or without) and exposure to the PRRSV. One week after weaning, pigs were treated intramuscularly with 2.0 mL of a commercial PRRSV vaccine (Ingelvac PRRS MLV) or sterile saline and housed 4/pen (2 barrows and 2 gilts). Pigs were inoculated 3 weeks after vaccination with sterile medium or PRRSV (MN184). This vaccination protocol has provided high protection against experimental PRRSV infection. (Thacker et al., 2000). Blood samples were collected from pigs upon arrival to the biosafety laboratory to corroborate PRRSV-naïve status. Pigs were given antibiotic-free diets that meet or exceed all nutrient recommendations (NRC, 1998). Growth performance, manure output and composition, and GHG emissions were determined from manure collected from each pen. The study was carried-out for 4 weeks after PRRSV inoculation and used a total of 3 experimental units (i.e., pens) per treatment (i.e., 48 pigs in total). The mitigation strategy tested was the effect of vaccination on pig growth and GHG emissions.
Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection caused significant reductions in feed intake which led to reductions in rates of gain and body weight. The infection also caused a reduction in diet digestibility leading to greater manure nutrient output per unit of feed intake and increased greenhouse gas (GHG) production from the stored manure. The impact on GHG production is particularly striking when the data are expressed as litters of gas per kilogram of body weight gain. The increased gas production combined with reduced rates of gain results in more than a tripling of gas production per unit of gain for all of the gases. Vaccination against PRRSV appeared to offer little benefit in terms of animal performance, manure nutrient output, or gas production from manure. Results of the gas production data are presented in Table 1.
Antibiotics and Antibiotic Alternatives
Experimental Design: Seven hundred twenty-four, mixed sex pigs were placed in 11 rooms at the SERB to determine the effects of rearing pigs without antibiotics on growth performance. Pigs were blocked by (body weight) BW and gender and allotted to room and pen with 10/11 mixed-sex pigs/pen. Control pigs consumed diets (Table 2) containing antibiotics and were treated with injectable antibiotics when deemed necessary. Antibiotic-free animals consumed diets with alternatives to antibiotics and received no injectable antibiotics. If sick animals did not respond to antibiotic alternatives, they were removed from the experiment.
Pigs were weighed at the start and end of each dietary phase, and mortality and morbidity were recorded daily. Data were analyzed using the general linear model (GLM) procedure in SAS (statistical software). During the nursery phase, control pigs grew faster (P<0.02; 0.449 vs 0.426 kg/d), and consumed more feed (P<0.05; 0.694 vs. 0.660 kg/d) than antibiotic free animals, resulting in similar (gain to feed ratio) G:F.
Similar average daily gain (ADG), average daily feed intake (ADFI) and G:F were observed throughout the grower phases, and therefore the increased BW of control-fed pigs was maintained and tended (P=0.06) to be heavier at the start of the finisher phases (86.0 vs. 84.5 kg). However, antibiotic-free animals grew 3% faster (P<0.01) and had 6% better G:F (P<0.001) in the finisher phases.
As a result, there was no overall effect (P>0.10) of treatment on ADG, but there was a trend (P = 0.08) for increased ADFI (2.11 vs. 2.07 kg) and reduced (P<0.05) G:F (0.518 vs. 0.527) in control pigs compared to antibiotic-free. Thirty antibiotic-free animals (8.3%) were removed from the study compared to 11 control (3.0%). In conclusion, antibiotic-free management can yield a similar growth performance to conventional systems, but the limited disease treatment options may limit the number of pigs marketed under this management system.
The objective of the study was to determine the impacts of a dirty environment leading to increased pathogen load and salmonella infection on animal performance, manure output and composition, and GHG production from the stored manure. 24 3-week old pigs were transported from the VT swine facility to the Biosafety Laboratory on campus and randomly allotted to one of the following health statuses: 1) High (clean room); 2) Medium (replicated clean on-farm environment); 3) Low (replicated “dirty” farm environment); or 4) Low + Salmonella challenge. Pigs were housed in individual metabolism stalls and fed the same antibiotic free diet as for the VT PRRSV trial. All pigs were assessed for fecal salmonella shedding which is indicative of an active infection upon arrival and found to be negative, and the feed was checked for salmonella contamination and found to be negative. After 10 days of adjustment (31 d of age), pigs allotted to the infected group were orally inoculated with 1×10^9 CFU of Salmonella enterica serotype enterica serovar Typhimurium strain DT104 (ATTC; BAA-185, Manassas, Virginia), and pigs were monitored for growth rate and fecal output and composition for an additional 24 d. Manure was collected each day and the loaded into the manure storage containers. Gas production from the storage containers was assessed continuously throughout the day every other day for the duration of the experiment plus an additional 11 days after the animal trial ended.
Pig inoculated with salmonella exhibited elevated rectal temperatures for 4 d post-innoculation, and shed salmonella in feces for the full 19 days that fecal shedding was monitored. Maintaining pigs in a dirty environment (heavy fecal contamination of the pens) and salmonella infection resulted in equal reductions in the rate of gain and numerical reductions feed efficiency as compared to control animals housed in a clean environment. Emissions of methane from stored manure per unit of weight gain was increased for both the dirty group and the salmonella group by more than 3 fold; and emissions of CO2 and N2O were increased by almost 50% for the dirty group and by 2 fold for the salmonella group.
The effect of Salmonella infection on the gut microbiome are currently being determined. Correlations between greenhouse gas production and key microbial population members will be determined.
The impact of PRRSV and salmonella infections on feed intake was modeled as a time dependent process relative to initial infection and incorporated into the NRC growth model. Although PRRSV vaccination is not completely effective, it did provide partial protection which modified the time course of the infection. The PRRSV vaccination effect was also modeled as a time dependent process which was additively applied to the disease equation. The model predicted intake and growth depressions for both pathogens and the effect of vaccination with minimal mean and slope bias indicating the model represented the data well. Surprisingly the salmonella equation also did well in describing the negative effects of an e-coli infection suggesting that it could be used to predict the effects of other digestive pathogens. The reductions in feed intake explained all of the changes in animal performance, and thus no additional equations were required to simulate potential decreases in diet digestibility or increases in animal maintenance requirements.
The modified model was incorporated into the grower submodel of the overall barn model to allow simulations of PRRSV and salmonella infections and PRRSV vaccination.
The Swine Environmental Research Building (SERB)
The Swine Environmental Research Building (SERB) is set up at a scale that can validate the results of pilot scale studies done elsewhere. It houses 720 pigs in 12 rooms with 6 pens per room and 10 pigs per pen. Manure is quantitatively collected and stored in a deep pit under each side of the room (3 pens of 10 pigs each). The two manure pits in each room are divided by a wall under the central walkway. The building is equipped with a centralized laboratory capable of monitoring GHG emissions from each independently ventilated room. Pigs will be supplied by Purdue or obtained from a commercial source at weaning, blocked by weight and sex and randomly assigned to treatments.
Dr. Greg Thoma, Dr. Richard Ulrich and Dr. Jennie Popp – University of Arkansas, Dr. William Salas and Dr. Chengsheng Li – DNDC Applications, Research and Training
Why Develop Models for Pork Production and Environmental Footprint?
Change in complex systems can occur either systemically, for example by government policy or regulation, or by adoption of new practices by individuals followed by wider adoption where the new practice is effective. This is costly and early adopters incur high risk of failure. This risk can be reduced through good decision support systems to aid in the selection of optimal practices – in effect, with a good model of the system, adoption of management techniques or technology can be tested by simulation before physical implementation.
This is the fundamental utility of models: they provide an inexpensive low risk alternative to experimental trial and error. The swine production model being developed for this project is based on the National Pork Board (NPB) Pig Production Environmental Footprint Calculator written at the University of Arkansas and first released in May 2011.
The National Academy of Sciences reported that EPA methodology should be improved by replacing emission factors with “process-based” models.” The tradeoff is that process-based models are more complex. Our team worked with the National Pork Board to create a process based emission model for swine production to serve as the foundation for a decision support system. This combined emission and cost model, the Pig Production Environmental Footprint Calculator (V2), was released in June 2013, and V3 will be released in Fall, 2015.
This model estimates GHG emissions, water use, land occupation and day-to-day costs from multiple farm operations to identify major contributions and provide a test bed for evaluating potential reduction strategies. The model requires readily available input information such as the type of barn, animal throughput, ration used, the time in the barn, weather for the area, type of manure management system as well as energy and feed prices. The model output includes a summary GHG emissions, water consumption, land occupation and costs by source, of as well as feed and energy usage for the simulation.
Integrate process-models of swine production with coupled life cycle assessment (LCA) and economic models to create a decision support tool to identify economical swine production system options which minimize GHG emission and increase sustainability of production systems.
Improve existing process algorithms to capture effects of barn climate control, feed phases, water distribution, solar insolation, and manure application technology on GHG emissions.
Expand and improve the user interface, making it more intuitive and user-friendly.
Expand the feed ingredient list and improve estimations of important feed characteristics needed for the model.
Develop economic algorithms and compile relevant cost databases to capture the costs of day-to-day activities that entail water use and generate GHGs on farm.
Research Summary: What Have We Done? What Have We Learned?
Scale of the farm and manure systems
The model was converted from barn-level to a farm-level tool by integrating the barns and manure systems together through the model input procedures. In this way the emissions from the various on-farm operations can be compared on the same basis and put into perspective with regard to emission sources. There can be up to ten barns, each with its own associated manure system (subfloor, deep pit and, added in year 4, dry bedding) and 10 separate downstream manure handling systems (lagoon, outside storage and, recently added, a digester). Each barn can have its manure stream routed to any downstream manure system enabling streams to be combined for processing before going to the fields. An algal turn scrubber option can be added as an adjunct to any downstream system.
All of the manure handling systems, both those associated with a barn and those downstream of the barns, were written at the University of Arkansas and all but the digester are process-based. A digester option was added with options for burning the produced methane as barn heat or for producing electricity. Emissions are calculated for the transport of manure to the fields but not for emissions after application.
Growth, performance and amino acid inclusion in rations
The National Research Council (NRC) growth and performance model was integrated into the full farm level model in order to link ration characteristics and growth performance. We have closed the mass balance over the farm for carbon, nitrogen, phosphorous, water and manure solids. Addition of the NRC model also brought in the effects of ractopamine and immunocastration management options.
Testing of the revised growth equations with respect to the effects of individual amino acids (AA) was completed and a manuscript has been partially drafted. A revised equation predicting the effects of heat stress on feed intake was derived and incorporated into the model resulting in much better predictions of these effects than provided by the native NRC equations. Equations describing the impact of heat and cold stress on energy maintenance costs were also constructed, but have yet to be incorporated into the model. These latter 2 efforts were carried out primarily by a postdoctoral student employed on the National Animal Nutrition Program (NRSP-9) with the resulting equations made available to the project. Two manuscripts describing this work have been drafted and will be submitted in Fall, 2015. Finally, a method of deriving model settings to match observed rates of daily gain and feed conversion efficiency was devised and recently passed onto the barn model team for incorporation into the barn model. This will allow the model to be easily calibrated to observed gain and feed efficiency as input by the user.
We updated the model weather files from the MERRA database for each of the 3102 counties in the U.S. These files have, in addition to temperature and humidity, other useful information such as precipitation, solar insolation, subsurface temperatures at various depths, and snow cover. The additional MERRA information facilitated addition of a solar panel option and will be used to estimate rainwater contribution to outside manure handling facilities and of solar insolation on inside barn temperatures.
What Is the DNDC Model?
The DNDC (DeNitrification and DeComposition) model was developed for quantifying N2O emissions from agricultural soils in the late 1980s (US EPA, 1995). By including fundamental bio-geochemical processes of carbon and nitrogen transformations, DNDC was extended to model soil C sequestration and other trace gases (e.g., methane, nitric oxide, ammonia etc.) in the early 1990s.
DNDC consists of two components. The first component entails three sub-models and converts primary drivers (i.e., climate, soil, vegetation and anthropogenic activity) to soil environmental factors (i.e., temperature, moisture, pH, Eh and substrate concentration gradient). The second component consists of nitrification, denitrification and fermentation sub-models; and simulates production/consumption of N2O, NO, N2, NH3 and CH4 driven by the modeled soil environmental conditions [see graphic below]. With the bio-geochemical reactions embedded in the model framework, DNDC can predict the turnover of soil organic matter and the consequent trace gas emissions and nitrate leaching losses.
With input from industry and academic experts, our feed ingredient database was revised to better capture the expected range of ingredients typically available to producers in the US. Carbon, water and land footprint data as well as nutritional characteristics for the NRC growth equations were compiled for each feed ingredient. Economic models, that estimate the cost of feed, manure handling, utilities (water, electricity, gas, propane and diesel), dead animal disposal and immunocastration were integrated into the model. Capital costs are not considered. We are conducting cost benefit analyses on combinations of operations, manure management and dietary feeding systems aimed at reducing GHG emissions. These will help identify incentives to minimize mitigation strategy cost. Routines have been developed that will allow the user to download a set of updated prices for utilities and major feed ingredients.
DeNitrification and DeComposition (DNDC) Model (Soil)
The DeNitrification and DeComposition (DNDC) model requires numerous weather and site inputs, many of which are output from the environmental calculator, and others which require site-specific geographical characteristics (e.g., soil type). We analyzed the agricultural area of each continental-US county using agricultural classes from the 2013 NASS Cropland Data Layer. For each county, we assigned the mean latitude/longitude of all agricultural pixels as the agriculture-weighted centroid from which representative weather data will be extracted.
County soils data are derived from the NRCS General Soils Map (STATSGO). We derived the spatial intersection of STATSGO soil polygons with county boundaries. We summarized top soil data for each soil polygon from 0 to 10cm depth for clay fraction (a proxy for soil texture), bulk density, organic matter fraction (to estimate soil organic carbon, SOC), and pH. Modeled results will be based on either the comprehensive set of soil polygon attributes or a representative distribution of soil attributes for each county (depending on timing and available computing power).
The model will enable the user to find hot spots in their emissions profile, evaluate the effects of operational changes, and estimate the emissions from facilities during the design stage. The further addition of an operational economic model will provide the ability to perform cost/benefit analyses of practices that can change impact GHG emissions (see video).
Work will continue on this project through Spring, 2016.
Figure 1. Diagram of the DeNitrification and DeComposition (DNDC) model
Why Does This Matter?
The environmental footprint model, with improved algorithms for manure management, economics, and animal performance provide high resolution and flexible decision support for the swine industry. The model enables users to identify hot spots in their emissions and water/land use profiles, evaluate the effects of operational changes, and estimate the emissions from facilities during the design stage. The further addition of an operational economic model enables cost/benefit analyses.
These enhancements support evaluations of dietary energy, protein, and amino acid content for much of the life cycle and immunocastration and the use of ractopamine during the growth cycle. They also allow assessment of the performance, economic, and environmental impact of transient health events during the growth cycle with respect to whole farm operation.