Representative beef feedlot models in both western and eastern Canada, as described in Legesse et al. (2015) and Mengistu et al. (2025), were used as the basis for the estimated economic outcomes and GHG impacts of incorporating different amounts of cull potato waste in beef cattle diets presented here. In Legesse et al. (2015), three typical Canadian beef finishing animal class systems were described and used to estimate their respective greenhouse gas emissions over time: calf-fed systems, yearling systems and yearling grass-fed systems. Calf-fed systems contain weanling calves that were immediately placed on finishing diets; yearling systems comprise calves fed a backgrounding diet before finishing; and yearling grass-fed systems comprise calves that are backgrounded, placed on pasture in the spring and then subject to a short finishing period. The feedlot production models from Legesse et al. (2015) were further refined in Mengistu et al. (2025) to explicitly allow for the inclusion of cull potato waste in the different finishing diets, based on consultation with beef cattle producers and crop and livestock specialists in Manitoba and Ontario, as well as the Beef Cattle Nutrient Requirement Model (NASEM, 2016) to guarantee constant dry matter intake (DMI) under different cull potato inclusion rates. Some of these beef producers are currently engaged in a barter trade agreement with their neighboring potato producers to obtain cull potato waste for animal diets (Mengistu et al., 2025), and provided estimated exchange costs based on their current arrangements. Thus, we used the beef production models from Legesse et al. (2015) and cull potato diet and GHG modeling of these production systems from Mengistu et al. (2025) to calculate the economic costs and returns to the different cull potato inclusion rates in this study.

The assumed locations of both feedlots were North Cypress-Langford, Ecodistrict 759, Manitoba, and in Melancthon, Ecodistrict 556, Ontario, as described in Mengistu et al. (2025). These study domains (Figures 1a,b) were located in Census Consolidated Subdivisions with a high number of both potato and feedlot cattle producers (Statistics Canada, 2021) and thus had increased potential to utilize potato waste. In each Census Consolidated Subdivision shown on the map, the total number of producers of both cattle and potato from the latest Canadian Census of Agriculture are indicated.

The cost of production, profit margin and break-even analyses in both feedlot systems was calculated for three animal classes: weanling calves that were immediately placed on finishing diets (calf-fed); yearling-fed calves fed a backgrounding diet before finishing; and yearling grass-fed calves that were backgrounded, placed on pasture in the spring and then subject to a short finishing period. Barley grain was the main energy source in western Canadian feedlot diets, and corn supplemented with soybean meal in feedlot diets is the energy source in eastern Canada (Legesse et al., 2015). Barley silage was assumed to be the main forage fed to feedlot cattle in western Canada, while it was corn silage in eastern Canada (Legesse et al., 2015). We thus estimated the economic impact of substituting barley and corn grain with cull potatoes at rates of 15 and 30% of the dietary dry matter intake (DMI) and compared these diets to the standard grain based diets for both regions. We considered a maximum of 30% replacement of grains for cull potatoes, as that is the highest level of substitution deemed feasible without potentially negatively impacting the growth performance of feedlot cattle (Charmley et al., 2006). A full description of the diets and nutritional profile can be found in Mengistu et al. (2025).

Animal diet composition was adjusted to maintain consistent animal growth performance for each level of inclusion of potato waste to ensure comparisons for each feedlot are not impacted by differential growth outcomes. The initial body weight (BW), average daily gain (ADG) and average daily DM intake (kg) of the cattle types were as reported by Legesse et al. (2015) and Mengistu et al. (2025) and assumed to be similar between western and eastern Canada (Sheppard et al., 2015). Steer and heifer characteristics from Legesse et al. (2015) were averaged for ease of exposition. Thus, the average days on feed at the feedlot were 240, 153, and 105-d for calf-fed, yearling-fed and yearling grass-fed cattle, respectively. Average prices (in terms of $/hundredweight) for feeders and finished cattle between 2019 and 2024 (Statistics Canada, 2022b) were used to estimate economic returns for each of the feeding scenarios for each animal type and inclusion level (15 and 30%) of potato waste.

After calculating the associated costs of production and returns to different potato waste inclusion rate scenarios, a partial budget analysis was performed to assess the economic impact of inclusion of potato waste relative to baseline costs for the animals with standard diets without potato waste using a standard enterprise budgeting production calculator from Manitoba Agriculture (n.d.-a, n.d.-b). Partial budget analysis estimates the cost of production impact relative to a business as usual baseline, by comparing budget costs across scenarios and identifying budget gains (where costs decrease versus the baseline) and losses (where costs increase versus the baseline).

To further align the economic analysis of the impact of inclusion of potato waste with standard beef cattle industry tools, we also performed a break-even analysis across potato waste inclusion rates (Manitoba Agriculture, n.d.-a, n.d.-b). Break even analysis estimates the cattle prices at which producers under different production systems will exactly break-even and fully offset costs of production with fed animal revenues. Feedlot producers have some flexibility in participating in feeder and fed animal markets, and can often arbitrage seasonal price fluctuations in these markets. Thus, the break-even analysis provides guidance on ranges of prices that allow for break-even economic outcomes.

Greenhouse gas emissions associated with inclusion of potato waste in feedlot diets were estimated using the Holos model (Agriculture and Agri-Food Canada Holos Software Program, n.d., Holos - agriculture.canada.ca) for each feeding scenario, as detailed in Mengistu et al. (2025). The system boundary included the beef cattle feedlot finishing operations with the associated crop land required for grain and silage production. On-farm GHG emission sources were: enteric and manure methane (CH₄), direct and indirect nitrous oxide (N₂O) emissions from run-off, manure, fertilized soils and cropping; and carbon dioxide (CO₂) from fuel energy use for on-farm cropping activities. Off-farm GHG emissions from inputs included the production and transport of cull potatoes, grains, and soybean meal (SBM), as well as the processing of SBM. Emissions estimates from fertilizer and herbicide manufacture and equipment use were also included. Carbon dioxide equivalents (CO₂e) were used to express emissions with a 100-year global warming potential of CO₂ = 1, CH₄ = 28, and N₂O = 265.

In addition to the economic rationale for considering inclusion of potato waste in feedlot diets, reducing GHG emissions and the overall environmental footprint of the beef feedlot sector was also examined from a circular bioeconomy perspective (Ominski et al., 2021).

The inclusion of potato waste in feedlot diets has both direct and indirect impacts on feedlot GHG emissions. There are direct effects due to the GHG emissions associated with potato production, as well as changes in enteric and manure methane emissions from the animals due to the changes in diet composition. There are also indirect impacts as a result of potato waste being substituted for barley, corn and soybean meal in feedlot diets, which alters the emissions associated with animal feed production. Finally, as cull potatoes are can be considered waste by-products, diverting cull potatoes from landfill to cattle feed helps reduce the GHG emissions associated with this disposal practice (Gooch et al., 2019). Full estimation of the net GHGs from different inclusion rates of potato waste has been presented in Mengistu et al. (2025). These calculations assess both the direct enteric and manure methane emissions from the main feed ingredients (barley, corn, soybean meal, potato) as well as the indirect embedded GHG emissions associated with production of these main diet ingredients. As cull potatoes were incorporated into feedlot diets, the combined impact of both the direct and indirect effects of including more potato waste in feedlot diets reduced per head GHG emissions on net as compared to when standard feed grains were included in the diet. They also showed additional GHG offset potential due to avoiding the emissions associated with landfilling cull potatoes. The complete list of estimated GHGs for each animal class and feeding strategy is shown in Table 8.

Extending the GHG assessment from Mengistu et al. (2025) to include the economic analysis, inclusion of potato waste was a clear ‘win-win’ for feedlots from both a feed cost and GHG emission perspective (Figure 2), rather than a trade-off between climate mitigation and economic cost of production considerations, as greater inclusion of potato waste also led to greater reduction in per head GHG emissions.

The proportional rate of change of feed costs and GHG emissions varied between western and eastern feedlots (Figure 2). More specifically, the relative impact of inclusion of potato waste on emissions vs. feed costs was less in western calf-fed systems (1.25 kg CO₂eq/$), than in eastern calf-fed systems (4.20 kg CO₂eq/$). This can be attributed to regional variation in feed costs between barley, corn and soybean meal, as well as their variable contribution to beef production and growth. It is also a reflection of the fact that GHG emissions associated with the production of barley grain are lower than those associated with the production of corn and soybeans (Desjardins et al., 2020).

Yearling systems also showed both an economic and GHG win-win as a result of including potato waste in the diets, with reductions in both per head feed costs and GHGs (Figure 3).

Circular economy strategies look for different methods to decouple economic production from primary resource use, switching from a ‘take-make-waste’ linear economic system to one with a closed loop system that repurposes and upcycles waste into new productive uses. In the agricultural sector context, Velasco-Muñoz et al. (2021) highlight that strategies like using agricultural waste such as cull potatoes as feed for livestock was an example of ‘resource cascading’ and the establishment of a more closed loop circular economic system. They also indicate that economic analysis of such circular economy strategies for the agricultural sector is limited, and more research into the application of circular economy principles to agriculture is necessary. Analysis of the real world examples used in this manuscript from two current Canadian feedlots already partnering with neighboring potato producers to exchange resources offers an important opportunity to add to our body of knowledge of the precise economic and environmental costs and benefits of promoting a circular economy structure in Canadian agriculture.

For Canadian horticultural producers and processors, cull potato piles on farm and land application are the most common disposal methods for these waste by-products (Bell, 2015; Gooch et al., 2019). Landfilling and cull piles are sources of additional methane emissions from potato production (De Corato et al., 2018). Thus, the circular economy strategy of diverting cull potatoes into livestock feed avoids landfill emissions as well as minimizes pests or other vermin in cull potato piles (Olsen et al., 2001). Table 9 uses emissions factors from Lee et al. (2017) on landfill waste and applies them to the potato waste used in the feedlot diets in our study, following Mengistu et al. (2025). The practice of including potato waste in feedlot diets can therefore offset remaining GHG emissions from feedlots by reducing landfill emissions as a result of potato disposal. At 30% of dietary DM, upcycling potato waste into cattle feed offset the GHGs from the feedlot sector by more than 60% and up to almost 90% in the case of Western calf-fed animals.

Consequently, diversion of potato waste to cattle feed can serve as an effective GHG mitigation tool for beef feedlots. By way of comparison, feed additives such as 3NOP have been estimated to reduce beef methane emissions by an average of 30%, but with potential negative animal production consequences (Zhang et al., 2021). In contrast, avoidance of landfill emissions by incorporating cull potato waste into feedlot diets reduced GHG emissions from the agriculture sector more broadly between at least 67% and up to 89% (Table 9) with little consequence to animal production indicators.

From both the individual feedlot budget and greenhouse gas mitigation perspectives, encouraging diversion of agricultural by-products like cull potatoes into feedlot diets is clearly a win-win, by lowering production costs as well as per head GHG from feedlots. However, presently there are few formal systems in place to enable feedlot producers elsewhere in Canada to easily incorporate agricultural by-products into feedlot diets. These logistical costs may serve as a barrier for feedlots to more regularly incorporate potato waste and other food by-products into their operations despite the direct economic and GHG mitigation benefits. A recent review by Prokopy et al. (2019) highlights that the economic business case for management practices is a necessary condition for environmental BMP adoption, but not necessarily a sufficient one. More complex factors, like farmer awareness and confidence in the performance of management practices, information seeking and access, regulations and effective training and well-regarded stewardship programs are often much more important in explaining farm system changes. More investigation of what similar types of information and incentives (like cost sharing programs e.g.) might be required to facilitate more circular economic exchanges between field crop producers and feedlots are warranted.

On a broader, industry wide level, given our calculations, there may be further challenges in scaling up the practice and additional strategies may need to be considered to facilitate a switch to a more circular economic system of regularly using agricultural by-products for animal feed. In our analysis, we modeled emissions for feedlots with 1,000 head. For the best economic and GHG emissions case scenario with inclusion of 30% DM potato waste in feedlot diets, this would result in 11 to 13 kg of cull potato waste being consumed per animal per day. For feedlots with 1,000 head, this would require access to 11,000 to 13,000 kg of potato waste per day for a period of between 100–240 days on feed. Given our assumption of a truckload capacity of 25 metric tonnes, three to four truckloads of potato waste per week would be required to meet the needs of a 1,000 head commercial feedlot.

Precise estimates of the feedlot population of different provinces are not available through Canadian national statistics (Vergé et al., 2008). However, based on other sources, approximately 10% of Manitoba’s beef herd are in feedlots (Manitoba Agriculture, 2023) representing about 40,000 head. At a maximum 30% DM inclusion rate of about 12 kg per day per head, including potato waste in these diets over the course of 100 days on feed would require ⁓48,000 tonnes of potato waste for yearlings and more than 115,000 tonnes for calf-fed feedlot systems. The scale of the feedlot sector is much larger in Ontario than Manitoba, with hundreds of thousands of cattle (Vergé et al., 2008; OMAFRA, 2023). Consequently, Ontario would require a much larger volume of waste potatoes to ensure a consistent level in the diet of feedlot cattle.

Between 5 and 10% of potato yields end up as culls (Halliday, 2010). In 2024, Ontario produced more than 400,000 metric tonnes of potatoes, and Manitoba produced over 1 million metric tonnes (Statistics Canada, 2022a, 2022b). This would suggest that more than 40,000 tonnes of potato waste was potentially produced in Ontario and more than 100,000 tonnes in Manitoba. If we consider potato waste from other sources, such as potato processing facilities, this potential feed source becomes even greater. So, there appears to be significant scope for regular inclusion of potato waste in feedlot cattle diets in both provinces (Ominski et al., 2021), but transportation logistics would need to be addressed. A recent study by Second Harvest (Gooch et al., 2019) suggests that up to 25% of agricultural produce waste, such as cull potatoes, is currently landfilled or spread back on the land, with only about 12% of this waste stream being used as animal feed. Facilitating exchanges as described in this paper between rural feedlots and agricultural commodity producers would thus significantly reduce GHG from rural agricultural producers, as well as improve their economic bottom line. In addition, exchanges of waste by-products between agricultural producers have relatively small start up costs, vs. other potential systems for processing agricultural waste by-products such as anerobic digestion. There are currently no agricultural waste anaerobic digestion facilities in Manitoba (Canadian Biogas Association, 2023), and thus a waste by-product exchange between potato producers and feedlots in the province is a much more relevant option to reduce agricultural waste GHG.

For the beef sector, a more circular economy approach would increase the use of agricultural by-products, like cull potatoes as a principal feed for beef production. This could be extended further into joint consideration of human food and animal feed production with a view to increasing production of human agricultural food products whose waste by products are most suited as livestock feed (Van Zanten et al., 2016). This would reduce the demand for grain as feed for livestock and increase it as a source of food for humans. This circular economy shift across the beef value chain may result in employment opportunities, as recycling of waste products tends to be more labor intensive than primary production sectors (Wijkman and Skånberg, 2017).

This study presents a detailed assessment of the immediate potential benefits of incorporation of potato waste into the standard diets for several typical Canadian beef feedlot production systems. Utilizing some standard modeling assumptions on both beef production, budget analysis and GHG emissions, these case studies suggest that the potential for ruminants to ‘upcycle’ food and agricultural wastes to improve circularity in our agricultural systems is high, in line with other analyses (Van Zanten et al., 2016; Ominski et al., 2021). Nevertheless, more research and information is needed to improve our understanding on the full consequences of more circular economic approaches to both the livestock and field crop sectors. The findings in this study apply currently to Canadian beef production and potato waste as the chosen agricultural waste by-product. The results for other livestock sectors or other waste feedstuffs might vary, and a similar exploration of both the economic and GHG mitigation impacts would be necessary to extend findings fully beyond the systems represented in this research. In addition, although the systems represented in this paper are modeled on real barter trade arrangements currently in place in the Canadian context, further analysis is required to understand the likelihood of similar arrangements between other livestock and field crop producers, or what factors are key to their success. Finally, the scaling up challenges are likely to be significant, as circular economy approaches require the investment of infrastructure to consistently divert waste products into secondary uses, such as livestock diets. Full upcycling of agricultural waste by-products may thus be constrained by the potential additional costs required to maintain animal nutritional value and to limit risks to animal health through proper processing and storage of these alternative feeds, which may be greater than for methods used for traditional forages used in animal production. Relatedly, the logistical challenges of securing sufficient access to high quality agricultural waste by-products, in terms of potential transportation challenges, as well as overall supply volumes, will represent barriers to shifting current Canadian beef finishing systems, and other comparable systems internationally, to more inclusion of agricultural waste by-products as feedstuffs. Analyzing the optimal agricultural waste diversion and processing systems to encourage greater circularity between the field crop and livestock production sectors is beyond the scope of this study, but is a critical next step in developing more circular agricultural systems.