Transforming sustainability from concept to application through animal modeling in the swine industry

Introduction

With the increasing demand for animal protein projected for the next decades as world’s population increases, the perceived antagonism between intensive animal production and climate change will intensify. It is estimated that livestock agriculture accounts for 14% of total CO2 emissions of which 1.4% can be attributed to pig production (FAO, 2020, IPCC, 2019 and 2022). Social pressure, policy making, carbon tax and sustainable financial investing will necessitate applying more sustainable and efficient nutrition, production and management practices. However, with this new wave of environmental accountability comes a number of opportunities and challenges, especially related to on-farm applications that are both pragmatic and meaningful. Life Cycle Assessment (LCA) has become the acceptable methodology to evaluate the impacts on the environment over an entire life cycle of a pig production system (Thoma et al., 2011; Doumard et al., 2014; Mackenzie et al., 2015; Kebreab et al., 2016; Ottosen et al., 2019; Tallaksen et al., 2020). However, with this approach there is significant complexity, and uncertainty in the science and methodology, that can contribute to the confusion of implementing sustainable solutions on the farm. For example, some uncertainties include: 1) differences in LCA methodology; 2) time period to consider land use change (20, 50 or 100 years); 3) constantly updating ingredient inventories and databases (e.g GFLI 1.0 vs 2.0); 4) new scientific insights (e.g crop yields and fertilizer efficiency; reduced emission conversion factors for CH4 and N2O’s into CO2 equivalents (IPCC, 2019)). An example of how this rapidly changing “science” of environmental sustainability can lead to confusion, is comparing the estimates of average intensive pig production in different countries using 2020 vs 2023 LCA methods and databases: Brazil 5.83 vs 6.29 (+8%); Canada 3.22 vs 2.61 (-19%); NW Europe 3.86 vs 3.57 (-8%); Spain 4.13 vs 3.57 (-14%). Despite these changes in absolute values, there are still many opportunities to identify hot spots and improve the environmental footprint of a pig farm where feed accounts for 40-70% of green house gas emissions, and manure 20-30%, farm operations 5-15% and processing 5-8% (Groupe AGECO, 2018). To help facilitate more sustainable nutrition and management practices at the farm level, a digital twin or virtual replica of a pig production system is proposed (Watson™) to predict the various environmental impact categories including: carbon dioxide equivalents, acidification, freshwater, marine and terrestrial eutrophication, water scarcity, land use, and non-renewable energy resource use.

Digital Twin, an integrated solution

To be able to estimate the environmental footprint on a pig farm there are multiple components that need to be considered simultaneously, including animal biological responses, stochasticity or animal variation, feed formulation, optimization, and an LCA. These components are integrated into a software application (Watson™) or digital twin, as shown in Figure 1. Details of the animal biology model can be found in previous publications (Ferguson 2006; and Ferguson, 2015). In essence the animal biology component predicts the population growth and feed intake responses and excretions to nutrient, health, social and physical environmental constraints. These animal responses are combined with feed ingredients, manure management and farm operations as inputs into the LCA to predict the environmental footprint. It is then possible to measure the impact on sustainability of any change to one of these components, including nutritional and/or production changes.

The LCA component uses the SimaPro software, based on IPCC 2022 methodologies and GFLI 2.0 (2023), Agri-footprint 6.3 and Ecoinvent 3.9 databases to predict the environmental emissions, land use, and natural resource extraction throughout the life cycle of the pig until shipped from the farm. The LCA system boundary includes the environmental impacts of crop production, animal feed processing, feed production, animal husbandry and manure storage. The design and methods of the integrated system were independently reviewed and audited, and were found to be in compliance with ISO standards ISO 14040/44:2006. To test the veracity of the proposed integrated system, the predicted outcomes from 9 different global regions were compared with recent published literature. The results showed the accuracy of prediction were mostly within 1 s.d of mean published results across all impact categories.

Figure 1. A proposed application that integrates key components in a virtually replicate of a pig production system.

Opportunities to reduce environmental footprint

For simplicity sake, only changes in CO2 equivalents (CE) will be reported and discussed but this does not mean the other environmental footprint categories are any less important or impacted the same way. The results from simulating a number of nutritional and management practices that may influence the on-farm environmental footprint are summarized in Table 1. It would appear that CE responses to nutritional changes depends on the region (North America vs Europe) or more precisely on the base diets (Corn/Soyabean Meal vs Wheat/Barley/Mix Plant Protein sources):

1. Sourcing local versus imported ingredients can reduce CE from 2-11% depending on source and amount of imported ingredients. Noya et al. (2016) reported a 12% reduction in CE using local grown corn and wheat (EU) versus imported (USA/Argentina/UK);

2. Co-product ingredients can have both a positive (-9%) and negative (+11) effect on CE depending if they replace ingredients with high CE values, or reduce/increase N and CH4 manure emissions . For example, replacing corn with wheat middlings/bran and bakery meal may reduce the CE/MT of feed but may also increase the undigested organic matter and therefore increase manure CE emissions. Whereas replacing wheat/barley with similar co-products has little effect on the CE manure emissions. Ali (2018) showed a 3.5-7% reduction in CE when using different co-products. Similarly, van Zanten et al. (2015) reported a 3.4% reduction when replacing SBM with rapeseed meal in European based diets.

Table 1. Predicted changes in climate change with specific farm production changes and nutritional strategies. Values are expressed as kg CO₂ eq per kg farm gate live weight unless indicated differently.

Table 1. Predicted changes in climate change with specific farm production changes and nutritional strategies. Values are expressed as kg CO2 eq per kg farm gate live weight unless indicated differently.

3. Reducing N emissions and thereby lowering CE, by using synthetic amino acids and low protein diets at the expense of high soyabean meal inclusion can reduce CE by -1 to -7%, depending on the source of SBM. Monteiro et al. (2016) reported a +3% to -8% when replacing SBM with synthetic amino acids, with the range due to the source of soyabean meal. Reckmann et al. (2013) reported a 2% reduction with the inclusion of synthetic amino acids compared to a “standard” diet with no amino acids.

4. Providing preweaned piglets a good nutritional start in life can improve the quantity and quality of piglets weaned and therefore resulting in more pigs likely to express their genetic growth potential and reach market weight sooner and/or heavier, Based on this early life boost principle, it is estimated CE can be reduced by 2%;

5. The net effect of feed additives on reducing CE is dependent on the health status of the herd and the type of additive. In general, gut health additives reduce CE in proportion to their effect on improving feed efficiency, but typically they can reduce CE by 2-6%. Charron-Doucet and Dionne (2017) reported a similar relative decrease of 8.6% CE for every 10% decrease in FCR while Reckmann (2013) observed a 4.1% reduction in CE with a reduced FCR.

Similarly, improving on-farm management practices can also help reduce CE outputs. Results of the predictions from different management practices suggested:

1. Manure management has the potential to significantly reduce CE, especially moving away from open lagoon storage to closed tanks (-30% CE), or even enclosing open tanks can reduce CC by 6%. Likewise, underfloor pit management can also help reduce both NH₃ and CH₄ emissions, for example, daily emptying can reduce CE by 12% relative to every 4 months;

2. Improving herd health status from poor to typical commercial status can reduce CE by > 3%;

3. Reducing mortality by 1% point for sows, preweaned piglets, nursey and grow-finish pigs can reduce CE by > 1%;

4. Reducing feed waste through pellets (vs mash) and paying close attention to feeders and feed dispensing can reduce CE by 0.7% per 1% point reduction in feed waste. Commercial farms typical have between 1-12% feed wasted into pits and/or floor, therefore, there is the opportunity to reduce CE by 1-7%;

5. Any improvement in feed efficiency will reduce CE. In general, a 0.1 reduction in FCR will result in 0.07kg CE per kg farm gate weight (or 9kg CE/marketed pig), which is close to 2.5% reduction in CE.

Lastly pay close attention to operational efficiency during feed manufacturing to reduce resource waste such as spillage when loading ingredients, maintaining ingredient quality to reduce decrease in complete feed nutrient digestibility, reduce fines and rework of diets, and monitor and control energy utilization especially steam and condition temperatures.

Conclusions

With the increase in awareness of livestock’s environmental footprint it will be necessary to use tools that can help producers make informed decisions on how to improve the productivity or efficiency and reduce their footprint on their farms at similar or lower costs. The proposed integrated system is one such tool that provides the means by which alternative nutrition and management practices can be designed and implemented to reduce the environmental footprint by at the farm level. Results indicate a potential to reduce the carbon footprint on farm by 2-11% from nutritional solutions, and by 1-30% focusing on farm management practices. Operational efficiency can also contribute to reducing the environmental footprint of finishing pigs.

Presented at the 2024 Animal Nutrition Conference of Canada. For information on the next edition, click here.

Transforming sustainability from concept to application through animal modeling in the swine industry

Introduction

Digital Twin, an integrated solution

Opportunities to reduce environmental footprint

Conclusions

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