Tag: enteric methane

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Livestock Methane Emissions Estimated and Mapped at a County-level Scale for the Contiguous United States


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Purpose         

This analysis of methane emissions used a “bottom-up” approach based on animal inventories, feed dry matter intake, and emission factors to estimate county-level enteric (cattle) and manure (cattle, swine, and poultry) methane emissions for the contiguous United States.

What did we do? 

Methane emissions from enteric and manure sources were estimated on a county-level and placed on a map for the lower 48 states of the US. Enteric emissions were estimated as the product of animal population, feed dry matter intake (DMI), and emissions per unit of DMI. Manure emission estimates were calculated using published US EPA protocols and factors. National Agricultural Statistic Services (NASS) data was utilized to provide animal populations. Cattle values were estimated for every county in the 48 contiguous states of the United States. Swine and poultry estimates were conducted on a county basis for states with the highest populations of each species and on a state-level for less populated states. Estimates were placed on county-level maps to help visual identification of methane emission ‘hot spots’. Estimates from this project were compared with those published by the EPA, and to the European Environmental Agency’s Emission Database for Global Atmospheric Research (EDGAR).

What have we learned? 

Overall, the bottom-up approach used in this analysis yielded total livestock methane emissions (8,888 Gg/yr) that are comparable to current USEPA estimates (9,117 Gg/yr) and to estimates from the global gridded
EDGAR inventory (8,657 Gg/yr), used previously in a number of top-down studies. However, the
spatial distribution of emissions developed in this analysis differed significantly from that of
EDGAR.

Methane emissions from manure sources vary widely and research on this subject is needed. US EPA maximum methane generation potential estimation values are based on research published from 1976 to 1984, and may not accurately reflect modern rations and management standards. While some current research provides methane emission data, a literature review was unable to provide emission generation estimators that could replace EPA values across species, animal categories within species, and variations in manure handling practices.

Future Plans    

This work provides tabular data as well as a visual distribution map of methane emission estimates from enteric (cattle) and manure (cattle, swine, poultry) sources. Future improvement of products from this project is possible with improved manure methane emission data and refinements of factors used within the calculations of the project.

Corresponding author, title, and affiliation        

Robert Meinen, Senior Extension Associate, Penn State University Department of Animal Science

Corresponding author email    

rjm134@psu.edu

Other authors   

Alexander Hristov (Principal Investigator), Professor of Dairy Nutrition, Penn State University Department of Animal Science Michael Harper, Graduate Assistant, Penn State University Department of Animal Science Richard Day, Associate Professor of Soil

Additional information                

None.

Acknowledgements       

Funding for this project was provided by ExxonMobil Research and Engineering.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

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Evaluation of a Model to Predict Enteric Methane Production from Feedlot Cattle


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Purpose

Continual refinement of methods estimating enteric methane production in beef finishing cattle provides a more accurate assessment of the environmental impact of the beef industry.  The USDA-OCE publication “Quantifying Greenhouse Gas Fluxes in Agriculture and Forestry: Methods for Entity-Scale Inventory” identified conservation practices and management strategies for reducing greenhouse gas emissions while improving agriculture production (Eve et al., 2014).  In Chapter 5 a new method to estimate effects of nutrition and management on enteric methane production of feedlot cattle is provided.  The system recommends using adjustment factors to correct the IPCC (2006) tier 2 Methane Conversion Factor (Ym) of 3.0% of gross energy intake to an adjusted Ym.  Adjustment factors are used for dietary grain and fat concentrations, grain type and processing method, and ionophore use.  These adjustment factors let beef producers more accurately determine the enteric methane production associated with their individual finishing operation.

What Did We Do?

To evaluate this new model, we developed a database consisting of 36 refereed publications, with 75 treatment means.  The focus of this database was to identify published research relating to high concentration beef finishing that provided methane as a percent of gross energy, or provided enough information for calculation.  Treatments containing greater than 20% forage were excluded, as they are not representative of a high concentration finishing diet.  Additionally, treatment diets utilizing a methane mitigation agent were excluded from the database. 

What Have We Learned?

This database encompassed 75 treatment means containing a wide range in weight, intake and protein of the diets.  Body weight, dry matter intake, and dietary crude protein concentrations for the database ranged from 150 to 723 kg, 4.78 to 12.9 kg, and 9.4 to 23%, respectively.  Predicted Ym had a significant but relatively low correlation (r = 0.31, P = 0.0077) to actual Ym.  However, when one experiment (4 treatments) with very high methane values (likely a result of manure CH4) was removed, the correlation improved (r = 0.62, P < 0.0001), resulting in the following relationship:  Predicted Ym = 2.23 + (0.41 * actual YM) (r2 = 0.39, RMSE = 0.58).  Predicted g of CH4 produced daily were highly correlated to actual g of CH4/d (r2 = 0.63, RMSE = 22.61), and predicted CH4 produced, as a percentage of digestible energy intake, was highly correlated to actual CH4 per kcal of digestible energy intake, DEI (r2 = 0.46, RMSE = 0.61).  Under the conditions of this investigation, the new model moderately predicted enteric methane production from feedlot cattle fed high-concentrate diets.

Future Plans

The database will be expanded as refereed publications suitable to the selection criteria are identified.  Trials with greater forage inclusion will be evaluated to test the robustness of the model and evaluate the correlation to IPPC (2006) estimations. 

Corresponding author (name, title, affiliation) 

Tracy D. Jennings, Associate Research Scientist, Texas A&M AgriLife Research

Corresponding author email address  

Tracy.Jennings@ag.tamu.edu

Other Authors 

Kristen Johnson, Professor, Washington State University; Luis Tedeschi, Professor, Texas A&M University; Michael Galyean, Provost, Texas Tech University, Richard Todd, Soil Scientist, USDA-ARS; N. Andy Cole, Retired Animal Scientist, USDA-ARS

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

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Effects of Corn Processing Method and Dietary Inclusion of Wet Distillers Grains with Solubles (WDGS) On Enteric Methane Emissions of Finishing Cattle

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Abstract

The use of wet distiller’s grains with solubles (WDGS) in feedlot diets has increased as a result of the growing U.S. ethanol industry.  However, few studies have evaluated the use of WDGS in finishing diets based on steam-flaked corn (SFC), the processing method used extensively in the Southern Great Plains.  The effects of corn processing method and WDGS on enteric methane (CH4) production, carbon dioxide (CO2) production and energy metabolism were evaluated in two respiration calorimetry studies.  In Exp. 1, the effects of corn processing method (SFC or dry rolled corn – DRC) and WDGS inclusion (0 or 30% of diet dry matter- DM) were studied using a 2 x 2 factorial arrangement of treatments and four Jersey steers in a 4 x 4 Latin square design.  In Exp. 2, the effects of WDGS inclusion rate (0, 15, 30, or 45% of diet DM) on CH4 and CO2 production were measured in a 4 x 4 Latin square design. Results indicate that cattle consuming SFC-based diets produce less enteric CH4 and retain more energy than cattle fed  DRC-based diets.  When dietary fat levels were held constant, dietary inclusion of WDGS at 15% of diet DM did not affect enteric CH4 production, WDGS inclusion at 45% of diet DM significantly increased enteric CH4 production and WDGS inclusion at 30% of diet DM had variable effects on enteric CH4 production.

Purpose

Our objectives were to determine the effects of corn processing method and WDGS inclusion rate on enteric methane losses from finishing cattle using respiration calorimetry.

What Did We Do?

Steer in open circuit respiration calorimetry chamber.

Eight steers were used in two studies.  In each study steers were fed one of four diets at 2 x maintenance energy requirements in a 4 x 4 Latin square design.  Each period of the Latin squares included a 16 d adaptation period followed by 5 days of total fecal and urine collection and measurement of gas exchange in respiration chambers.  In Experiment 1 dietary treatments consisted of corn processing method (steam flaked -SFC or dry rolled -DRC) and WDGS inclusion rate (0 or 30% of DM).  All diets were balanced for ether extract.   In Exp. 2, cattle were fed SFC-based diets containing 0, 15, 30 or 45% WDGS (DM basis).  The calorimetry system consisted of 4 chambers with an internal volume of 6500 L.   Outside air was pulled through chambers using a mass flow system.  Gas concentrations were determined using a paramagnetic oxygen analyzer and infrared methane and carbon dioxide analyzers (Sable Systems, Las Vegas, NV)  Data were statistically analyzed using the Mixed procedure of SAS.

What Have We Learned?

In Exp. 1. no iteractions between grain processing method and WDGS inclusion were detected (P > 0.47).  Cattle fed DRC-based diets had greater (P < 0.05) CH4 production (L/steer, L/kg of DMI, % of gross energy intake, and % of digestible energy intake) than cattle fed SFC-based diets probably the result of differences in ruminal fermentation and ruminal pH.  Methane losses as a proportion of GE intake (2.47 and 3.04 for SFC and DRC-based diets, respectively) were similar to previous reports and to IPCC (2006) values but were somewhat lower than EPA (2012) values.  Grain processing method did not affect CO2 production (13 to 14 Kg/d).  WDGS  inclusion rate did not affect CH4 or CO2 production.  In Exp. 2, CH4 production (L/d) increased quadratically (P = 0.03) and CH4 production as L/kg of DMI and as a proportion of energy intake increased linearly (P < 0.01) with increasing concentrations of WDGS in the diet.  Feeding WDGS did not affect (P > 0.23) total CO2 production.  Conclucions: Our results indicate that cattle consuming DRC-based finishing diets produce approximately 20% more enteric CH4 than cattle fed SFC-based diets.  When WDGS comprised 30% or less of the diet and diets were similar in total fat content, feeding WDGS had little effect on enteric CH4 but when fed at higher inclusion rates enteric CH4 production was increased by approximately 40%.

Future Plans

Over 80% of the enteric methane emissions of the U.S. beef cattle herd are produced by cows, calves, and yearling on pasture.  Therefore, additional research will study the effects of supplementation strategies and forage quality on enteric methane production by cattle.

Authors

N. Andy Cole; Research Animal Scientist/Research Leader; USDA-ARS-CPRL, Bushland, TX andy.cole@ars.usda.gov

Kristin E. Hales, Research Animal Scientist, USDA-ARS-MARC, Clay Center, NE

Richard W. Todd, Research Soil Scientist, USDA-ARS-CPRL, Bushland, TX

Ken Casey, Associate Professor, Texas AgriLife Research, Amarillo, TX

Jim C. MacDonald, Associate Professor, Dept. of Animal Science, Univ. of NE, Lincoln

Additional Information

Hales, K. E. , N. A. Cole, and J. C. MacDonald.  2013. Effects of increasing concentrations of wet distillers grains with solubles in steam-flaked corn-based diets on energy metabolism, carbon-nitrogen balance, and methane emissions of cattle. J. Anim. Sci. (in press)

Hales, K. E. , N. A. Cole, and J. C. MacDonald.  2012. Effects of corn processing method and dietary inclusion of wet distillers grains with solubles on energy metabolism, carbon-nitrogen balance, and methane emissions of cattle. J. Anim. Sci. 90:3174-3185.

Acknowledgements

Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA.  USDA is an equal opportunity provider and employer.

We wish to thank USDA-NIFA for partial funding through Project # TS-2006-06009 entitled “Air Quality: Odor, Dust and Gaseous Emissions from Concentrated Animal Feeding Operations in the Southern Great Plains”

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

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