July 2022

Evaluating production metrics in relation to sustainability in a wean-to-finish barn

Improving the sustainability of US pork production requires a better understanding of the relationship between the environment and production practices. Pork producers play a crucial role in environmental stewardship, however, the impact of production efficiency on greenhouse gas production has not been well established. Interpreting the influence of specific production metrics on greenhouse gas (GHG) production is essential for benchmarking and improving the environmental sustainability of pork production.

During the growth period, pigs generate three major greenhouse gases: carbon dioxide, methane, and nitrous oxide. Carbon dioxide is produced as a byproduct of maintenance and growth and is emitted through exhalation during respiration. Methane and nitrous oxide are generated by manure and output of these gases are dependent on the type of manure management system implemented in the barn.

The Wean-to-Finish Pork Sustainability Calculator was designed to provide producers with a tool to estimate the impacts of various levels of production efficiencies (i.e., feed efficiency and mortality), allowing them to determine how specific improvements in finishing can influence the environmental footprint. The calculator provides insight into greenhouse gas production at the individual and barn level to enable continuous improvement of pork production.

Wean-to-Finish Production Metrics

Data was collected for baseline closeout weight and days in the barn until market for wean-to-finish pigs (MetaFarms Production Index: Nursery, Finishing, Wean-to-Finish Closeout Performance, and Market Hog Sales, 2019).    Baseline average daily gain, dry matter intake, and feed efficiency curves were obtained for the wean-to-finish stage (PIC 2019 Wean to Finish Guidelines, 2019).

A mortality equation was designed to assume production of GHG from respiration, feed, and manure management system; calculated only for the period of time the animal is alive.

Total GHG emissions are sourced from the amount of gas emitted by live and dead pigs. Estimates for GHG production by live pigs follows the assumption that the pig reached market weight (281 lbs.). Estimates for GHG production by pigs that died follows the assumption that the pig reached the halfway point (140.5 lbs.). Barn size and mortality is set by the user.

mortality formula


From these assumptions, GHG emissions can be calculated based on mortality, manure management systems, feed efficiency, and feed type. All of which can be applied within specific production parameters set by the user. The calculator can be manipulated to compare current production practices and target closeouts for the barn. A percent change is generated to demonstrate the potential improvement or decline of the different production metrics' influence on emissions.
The calculator allows producers to understand how specific improvements in finishing can influence the environmental footprint of that barn. They can change production parameters such as mortality and feed efficiency and see the effect of those changes.

This Excel-based calculator provides changes in percentages and weight of carbon dioxide based on baseline and target values entered by the user. It offers insight into the level of greenhouse gas production at the individual barn level to enable continuous improvement and can be used at any time to gauge potential change implications.

Visit the Iowa Pork Industry Center website for additional details on sustainability in the pork industry.

screenshot calculator


Erika M. Johnson, Garland R. Dahlke, Lance H. Baumgard and Jason W. Ross, Iowa Pork Industry Center, 515-294-9910, garland@iastate.edu


Garland Dahlke

research scientist
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Erika Johnson

Erika Johnson

Lance Baumgard
Jason Ross