Economic and Environmental Impact of Increasing Soybean Meal Protein and Energy in Swine and Poultry Diets
This article is the 9th in a series highlighting the unique value of soybean meal to swine nutrition and health
By Micah Pope, R. Dean Boyd, David Holzgraefe, Henrique Monaco, and Mamduh Sifri*
Introduction
Soybean meal (SBM) is one of the most commonly used feed ingredients for swine and poultry nutrition. However, variation in SBM composition (both digestible amino acids and energy) impacts the final diet’s nutritional value, associated animal performance, and diet cost. This variability arises from different processing plants, times, or regions, and requires ongoing evaluation of SBM. In addition, there has been an increased focus on environmental impact, and on understanding how diet composition influences sustainability metrics such as greenhouse gas (GHG) emissions. It is assumed that improving the environmental impact of formulated animal diets will come at a cost, but the dynamics have not been fully explored.
We recently published two studies (Pope et al., 2023 and 2024) that expand on these issues and propose methods to quantify the economic and environmental impact of increasing SBM crude protein and energy in swine and poultry diets. Higher concentrations of digestible amino acids and energy result in increased SBM market value, and coincide with reduced dietary GHG emissions (gCO2e/kg). Understanding, quantifying, and effectively communicating these benefits requires reliable amino acid and energy values as well as credible, science-based estimates of the environmental impact of feed ingredient production. GHG values for feed ingredients commonly used in U.S. swine and poultry diets are presented here, as well as the environmental impact of SBM composition changes.
Ingredient Evaluation in Practice
Nutritionists may intuitively understand the impact of variable nutrient composition on animal diets, but may underestimate the true economic implications. While accounting for this variation is routine for nutritionists, it is important to think beyond regional SBM crude protein (CP) differences (typically ranging from 45.5 to 47.0%) and utilize more holistic methods to link that variation in ingredient composition to business outcomes. Specifically, quantifying how variation in ingredient quality or composition can and should impact decision-making (e.g. diet cost, diet composition, over or under formulating the diet, environmental impact). The value of SBM in the diet is determined by its amino acid concentration, the digestibility of those amino acids, and its current market price relative to other ingredients prices. The interaction of these factors impacts the ideal quantity of SBM in the diet. Methods are needed to quantify true ingredient value when these variables change.
We proposed a framework that can be utilized to complement core business units that need to evaluate SBM value from various processing plants/sources, and determine which is the most valuable in the diet in dollars per ton (Pope et al., 2023). Furthermore, including the latest science-based research on the environmental impact of feed ingredients enables formulations that quantify dietary GHG emissions. While not currently standard practice, consumer and policy driven mandates may soon require evaluation of the environmental impact of ingredient inclusion in formulated diets.
Increasing SBM Digestible Amino Acids and Energy
A recent study (Pope et al., 2023) presented a framework to quantify SBM value in swine and poultry diets, using digestible amino acids and energy as the primary determinants of end-user value. SBM samples were analyzed for moisture, CP, and 11 amino acids (AA). These values were regressed to estimate five SBM CP concentrations (44.0, 45.0, 46.0, 47.0, and 48.0% CP) and the corresponding energy, and then used in a formulation exercise. The estimated energy values increased as SBM CP increased. Least cost diet formulation software calculated the cost of diets for swine and poultry for the five SBM CP concentrations. For each scenario, the only change allowed during the least cost optimization was the individual CP concentration (and corresponding energy level) of SBM. Representative diets for four swine production phases were specified: lactation, nursery, grower, and finisher production. Three phases were specified for poultry: layers, broiler grower, and broiler finisher production.
Relative SBM economic value (dollar per metric ton) was determined based on the changes in the nutritional properties of the SBM, primarily digestible amino acids and energy (Boyd et al., 2023). To estimate the relative SBM value in the diet by CP concentration (44.0–48.0%), differences in diet cost were applied to the SBM based on the amount used per metric ton. Diets were formulated using average prices for two different price scenarios: 1) marketing years 2016/2017 through 2018/2019, and 2) marketing years 2020/21 through 2022/2023. For each 1% increase in SBM CP concentration from 44.0 to 48.0%, SBM nutritional or relative value increased (Figure 1) as the diet included less of the higher quality soybean meal (Figure 2), and lower overall diet costs (Figure 3).
The relative SBM value increased on average $10 per metric ton for swine and $12 per metric ton for poultry per ton of feed for each 1% increase in CP concentration from 44.0 to 48.0% (Figure 4). As SBM CP increased, formulated diets included more corn, less distillers dried grains with solubles (DDGs), less fat and less synthetic amino acids. Higher corn inclusion and lower fat and synthetic amino acid inclusion resulted in lower diet costs. Updating the ingredient prices to reflect changing market conditions (marketing years 2020/2021 through 2022/2023) resulted in an increase in SBM relative value to $16 per metric ton for swine and $19 per metric ton in poultry diets (Pope et al., 2024).
Ingredient prices significantly increased between these two periods (Table 1). Despite that, the increase in value as SBM amino acid and energy levels increase demonstrates that the relationship is resilient under different market price scenarios. These SBM relative values represent the additional amount that swine and poultry end users could pay for a higher SBM concentration without increasing overall diet costs. For example, assuming a relative SBM value of $10/MT for each 1% increase in CP concentration, if a swine feeder was offered 46% CP SBM at a market price of $350/MT, they could pay up to $360/MT for 47% CP (a $10/MT premium for 1% more CP) and reduce overall diet costs due the improvement in the nutritional value of the SBM. This analysis can be used to understand the economic value of SBM based on intrinsic product and compositional characteristics.
Environmental Impact of Improving SBM composition
Consumers are increasingly focused on shifting their purchasing power toward products that enhance environmental sustainability. This has led to governments and private industry developing strategic goals that aim to improve environmental sustainability. Changing consumer preferences and policy mandates may lead to changing the mindset on how diets are formulated. In animal production, this could include evaluating ingredients based on metrics that link to sustainability goals, including reducing greenhouse gases (GHG) (e.g., carbon dioxide, methane, and nitrous oxide), water consumption, and energy use.
Life cycle assessment (LCA) models quantify the environmental effects of individual feed ingredients used in swine and poultry production. LCA takes into consideration environmental impacts across the whole supply chain of livestock production to quantify the total environmental impact associated with a product. While methods for developing environmental models that account for these practices are still evolving, the LCA methodology is currently driving policy and company-driven mandates. To account for environmental impact in the formulation analysis, current science-based estimates of GHG emissions (gCO2e/kg) for each ingredient in the diet can be specified (Table 2). These estimates account for emissions attributed to supply chain activities through the production of the feed ingredient, but before its utilization as a feed ingredient in animal production.
In a follow up study (Pope et al., 2024), these ingredient-specific GHG emission coefficients were used in formulation to understand how changes in SBM composition (digestible amino acids and energy) relate to GHG emissions. Dietary GHG emissions (gCO2e/kg) decreased as SBM CP (and corresponding amino acids and energy concentrations) increased. For each 1% increase in SBM CP, GHG emissions decreased 4.8% in swine diets and 5.5% in poultry diets (Figure 5). Note that values presented are an average of the production phases in both swine (lactation, nursery, grower, finisher) and poultry (broiler grower, broiler finisher, layer). Each production phase resulted in the same trend, with decreasing emissions as SBM CP level increased (individual data not shown).
As previously discussed, when SBM CP increased, formulated diets included more corn, but less DDGs, fat, and synthetic amino acids. Corn had the lowest estimated GHG emissions coefficient of all energy grains and protein ingredients (see Table 2). Fat and synthetic amino acids had the highest GHG emission coefficients. Higher corn inclusion and lower fat and synthetic amino acid inclusion in the diets resulted in lower estimated GHG emissions overall.
In addition to reducing dietary GHG emissions, increasing SBM amino acid and energy levels does not appear to increase dietary CP. As SBM nutritional composition improved (higher digestible amino acids and energy), dietary CP level was not affected when formulating to minimize diet cost (Table 3). Excess dietary CP is the level above what is required to precisely meet amino acid needs for animal production and maintenance. Excess CP is the source of excreted nitrogen (N) (feces and urine). In North America, reduction of N excretion is often not an objective in swine and poultry production because the manure is collected, safely held and then spread as an organic fertilizer, reducing the need for inorganic N sources. However, this finding is critical to other regions that formulate to control dietary CP and corresponding levels of N excretion.
Implications
Improving SBM nutrient composition (higher digestible amino acids and energy) leads to economic and environmental benefits. Higher digestible amino acids and energy result in increased SBM market value and coincides with reduced dietary GHG emissions (gCO2e/kg). Understanding, quantifying and communicating these dynamic benefits in practice require reliable amino acid and energy values and science-based estimates of the environmental impact of ingredients. Improved nutritive quality of SBM coincided with increased corn grain demand in diets, which may create additional demand for corn, influencing crop producer decisions when optimizing crop rotation to maximize profit. Higher SBM value benefits end-users and enables additional value to be shared with participants in the value chain. Significant ingredient cost differences showed that the outcome of improved in SBM amino and energy levels is resilient, even with changing market conditions.
Conclusions
Using SBM with increased amino acid and energy concentrations is a means to reduce diet cost and diet impact on the environment (GHG emissions).
Increasing SBM amino acid and energy concentrations can allow reductions in total SBM inclusion in the diet; but a higher nutrient value as SBM quality improves enables users to pay more for higher CP SBM and still reduce diet costs overall.
While standardized methods for estimating emissions are evolving, competent GHG emission coefficients for ingredients based on best scientific estimates are presented here; these values can be used by swine and poultry producers who are monitoring the environmental impact of diets.
GHG reduction can be achieved without imposing added diet cost.
As SBM CP increases (higher digestible amino acid and energy concentrations) corn usage increases, which is a key driver for reduced dietary GHG emissions.
Increasing SBM amino acid and energy levels does not appear to increase dietary CP and the corresponding nitrogen excretion.
This publication provides a methodology for evaluating the economic and environmental impact of feed ingredients used in animal nutrition.
* Micah Pope is a Senior Consultant at Centrec Consulting Group, LLC. R. Dean Boyd is adjunct professor of Animal Nutrition at North Carolina State and Iowa State U. David Holzgraefe previously served as VP, ADM animal nutrition and feed technology. Henrique Monaco is a doctoral student in the Department of Agricultural and Consumer Economics at the University of Illinois. Mamduh Sifri is the owner of Sifri Solutions, LLC.
References
ANL (Argonne National Laboratory). 2018. GREET Model: the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) Model, Energy Systems. Argonne National Laboratory, Lemont, IL. Accessed June 2023. https://greet.es.anl.gov/.
Boyd, R.D., M. Sifri, D. Holzgraefe, B. Borg and M. Pope. 2023. Amino acid levels and energy specifications in SBM for poultry and pigs. Feedstuffs, June digital edition, page 10, https://informamarkets.turtl.co/story/feedstuffs-june-2023/page/10.
ECOALIM: LCA Data of Feedstuffs for Animal Feed. 2023. ECOALIM Database on the Environmental Impacts of Feed Ingredients (actual version: V8.1). INRAE, Paris, France. Accessed June 2023. https://eng-ecoalim.hub.inrae.fr/.
GFLI (Global Feed Lifecycle Assessment Institute). 2022. Environmental Impact GFLI 2.0 Database. Global Feed LCA Institute, Arlington, VA. Accessed June 2023. https://globalfeedlca.org/.
Pope, M., B. Borg, R.D. Boyd, D. Holzgraefe, C. Rush and M. Sifri. 2023. Quantifying the value of soybean meal in poultry and swine diets. J. Appl. Poult. Res. 32. https://doi.org/10.1016/j.japr.2023.100337.
Pope, M., R.D. Boyd, D. Holzgraefe, H. Monaco, and M. Sifri. 2024. Economic value and environmental impact of soybean meal in poultry and swine diets. J. Appl. Poult. Res. 33. https://doi.org/10.1016/j.japr.2024.100449.
