Date Full Report Received09/06/2018
Date Abstract Report Received09/06/2018
InvestigationInstitution: University of Minnesota
Primary Investigator: Dr. Jennifer Schmitt
Co-Investigators: Pedro Urriola, Dr. Gerald Shurson
Funded ByNational Pork Board
The current life cycle analysis of the environmental impacts of the pork industry developed for the National Pork Board (NPB) allows pig producers to calculate carbon, water and land footprint of their operations. However, feed ingredients and the environmental footprint that is associated with the production of these feed ingredients vary across the US. Likewise, manure management practices and the associated greenhouse gas emissions also reflect geographic and dietary variations. Therefore, the objective of this NPB funded project was to compare greenhouse gases (GHG), water, and land use of pork production when pigs are fed diets representing four alternative programs across regions of the U.S. For water and land, we looked at the impacts embedded in corn feed inputs on a per pig basis. For GHG emission we considered the lifecycle impacts of corn farming and pig manure production as well as emissions avoided from repurposing food waste, again on a per pig bases. For these impacts we created four feeding programs including: 1) the use of corn distillers dried grains with solubles (DDGS) and 2) dehydrated retail level food waste as approaches for recycling nutrients back into pig feed; as well as 3) the use of synthetic amino acids and 4) enzymes (i.e. phytase) as back-end diet supplementation strategies for minimizing the environmental impact of pork production. We developed these four feeding programs using nutrient composition and nutrient requirements from the National Research Council. These allowed us to formulate the diets using ingredients for three different regions across the US, and included the amount of corn in each feeding program from these regions. Corn production regions in the U.S. have different inherent environmental impacts, which we modeled using the Food Systems Sustainable Supply-chain model (FoodS3) that uses county level environment impacts of corn production, rather than using a single national average estimate. We also added spatial difference in manure impacts by estimating the volatile solids excreted in manure by the three regional feeding programs using county specific manure management practices. Using these estimates, we calculated the water and land use impacts of corn and
DDGS in regional pig feeding programs, as well as the GHG impacts from corn inputs and manure emissions. Our results suggest that the use of synthetic amino acids had the greatest impact on dietary inclusion rates of corn, which increased from 190 kg/pig marketed in the Mid-West control diet to 239 kg/pig marketed in the Mid-West diet with synthetic amino acids. Conversely, use of corn in DDGS and food waste feeding programs was less than compared with using the control feeding program. Use of phytase also decreased utilization of corn (187 kg/pig). The consequence of greater use of corn in the synthetic amino acid feeding program increased the associated greenhouse gas emissions (92.45 kg CO2 equiv./pig) compared with the control (74.40 kg CO2 equiv./pig). Use of less corn in the food waste and phytase feeding programs decreased the associated greenhouse gas emissions to 51.25 and 72.16 kg CO2 equiv./pig, respectively. Water use for growing corn used as the feed ingredient was greater in the feeding program using synthetic amino acids (16.91 m3/pig) and phytase (12.02 m3/pig) than control (11.58m3/pig). Using the DDGS and food waste feeding programs decreased water use from corn input to 11.39 and 9.06 m3/pig, respectively. Likewise, land use was reduced for the food waste (45.34 acres/1,000 pigs) and phytase (63.76 acres/1,000 pigs) feeding programs compared with the control feeding program (66.02 acres/1,000 pigs), but land use increased with the DDGS feeding program to 71.84 acres/1000 pigs. The increase in land use was due to the embedded corn in DDGS, to which we allocated 40.1% of all environmental impacts of ethanol production. This was an energy-based allocation following EPA guidelines. Intensity of GHG emissions for the control feeding program in the Mid-West (184.3 kg CO2 equiv./pig) was less than the Mid-Atlantic (244.1 kg CO2 equiv./pig) and Central regions (245 kg CO2 equiv./pig). We observed that using the food waste feeding program resulted in the lowest corn input greenhouse gas emissions totals compared with all other feeding programs evaluated in this study. However, for all GHG emissions, the control feeding program had the lowest GHG emissions. While use of synthetic amino acids decreased excretion of volatile solids in manure, it resulted in the greatest greenhouse gas emissions. These emissions are the result of proportionally greater use corn in the synthetic amino acid diets than any other diet (more corn was required to ensure that the diet met the Nutrient Requirement for Swine (NRC, 2012) in our modeled diets). The impact of feeding program on greenhouse gas emissions also varied among geographic regions, where the Mid-West region had the least per pig emissions regardless of the type of diets used in the feeding program. This variation is primarily due to the spatially different emissions of feed ingredients estimated with our FoodS3 model. As expected, water and land use were least for the feeding program based on food waste, while using synthetic amino acids in diets resulted in the greatest water and land use per pig produced. One important note, food waste was accounted for as true waste, thus we did not attribute the embedded impacts of production (for GHGs, water, and land use) to hog production. In conclusion, the results from this project suggest that the use of various feed ingredients and diet formulation strategies can result in different impacts on GHG, water, and land use. Therefore, U.S. pork producers can reduce the environmental footprint in pork production systems by selecting feed ingredients and managing the associated volatile solids in manure. These results show that pork producers can use feed ingredient selection and diet formulation strategies tailored to specific geographic regions of the U.S. to have even greater positive environmental impacts. However, future research is needed to determine the complete life cycle environmental impacts of all feed ingredients, supplements, and diet formulation strategies.
In summary, the results from this research suggest:
1. Greenhouse gas emissions resulting from corn used in pig diets have a large impact on the carbon footprint of pork production. Pork producers could displace corn with less carbon intensive feed ingredients, but alternative ingredients need evaluation. Likewise, pork producers can encourage corn producers to use practices that reduce the carbon footprint of corn production.
2. Although the type of feeding programs used in each region, affects environmental impact, the associated manure management practices implemented have a greater impact. Therefore, pork producers should implement best manure management practices that are suited to each region.
3. Future LCA research should focus on analyzing feeding programs that combine all factors evaluated in this project to estimate the environmental impacts of all the dietary ingredients commonly used in commercial pig diets.
For more information, please contact Jennifer Schmitt: firstname.lastname@example.org