Precision feeding as a tool to reduce the environmental footprint of pig production systems: a life-cycle assessment.

ABSTRACT

Nitrogen and phosphorus excretion are major sources of environmental contamination in growing-finishing pig operations. Nutrient excretion can be reduced by feeding pigs daily-tailored diets to their estimated nutrient requirements using individual precision feeding (IPF) techniques. This study modeled and evaluated the environmental impact of moving from conventional group 3-phase feeding (CGF) to IPF systems in Quebec, Canada, using life-cycle assessment with SimaPro software. The cradle-to-farm model included inputs and outputs of each subphase raw materials/feedstuffs production, feed mill processing, transport, animal rearing, and manure management. The model was identical for both treatments in all aspects except for the production of feeds and barn and manure emissions in the growing-finishing phases. All feed ingredients originated from Quebec, simulating agricultural practices using real management data from an average farm in Quebec. Based on observed pig growth data, the CGF and IPF systems were compared in the growing-finishing phase. IPF diets were modeled as the blend of 2 feeds (i.e., A and B), while CGF diets were stablished according to the industry. The evaluated impact categories were global warming potential (GWP), eutrophication potential (EP), and acidification potential (AP). The functional unit was 1 t of feed at the feed mill gate and 1 t of finished pig live weight at the farm gate. A Monte Carlo analysis determined the uncertainty of the growth performance results. Feeding programs were compared using analysis of variance. Corn was associated with elevated GWP and AP impacts, leading to higher impacts for diets with higher corn content. Feed B, which contained 83% corn, resulted in impacts of 645 kg of CO2-eq., 8.53 kg SO2-eq., and 4.89 kg PO4-eq. Diets with higher EP impact had a higher percentage of soybean meal. Feed A contained 25% of this ingredient and had an impact of 608 kg CO2-eq., 6.98 kg SO2-eq., and 5.57 kg PO4-eq. CGF diets had environmental impacts between those of feeds A and B. Compared to CGF, applying IPF programs during the growing-finishing phase decreased GWP by 7.6%, AP by 16.2% and EP by 13.0%. IPF significantly reduced the environmental impact in all categories through the more efficient use of nutritional resources by pigs. IPF could help to improve the sustainability of growing-finishing pig operations in Quebec and likely other regions using corn and soybean-based diets.

Individual precision feeding (IPF) provides a daily-tailored diet to each animal considering the variation in nutritional requirements among animals and throughout their growth. Thus, this feeding approach contrasts with the traditional group 3-phase feeding system, which provides the same feed for large groups of animals during a long period (e.g., 21 to 28 d). The IPF system has been proven to reduce nitrogen and phosphorous excretion by 30% and 40%, respectively, without compromising growth and while reducing feeding costs. However, understanding the environmental impact of different feeding systems requires a holistic approach. To do so, a life-cycle assessment which is a simulation of emissions taking into consideration the potential emissions from all the production stages that intervene in pig production was performed. Considering the entire production chain, from crop production to the finished pig at the farm gate, makes it possible to quantify the environmental benefits of transitioning from group 3-phase feeding to IPF. This study demonstrated that IPF reduces global warming potential by reducing carbon dioxide equivalent, including gases like nitrous oxide and methane emitted by barns and manure. Similarly, it lessens acidification potential, which impacts plant growth and water quality. Additionally, IPF decreases eutrophication potential by preventing excessive nutrients in water bodies, which cause harmful algal blooms. IPF might successfully lessen the environmental impact because it affects nutrient-use efficiency, which can reduce acidification and eutrophication environmental impacts. In the current scope, the main cause of global warming emissions in pig production is feed production. To minimize the environmental impact of pig production in Quebec, it is important to reduce the inclusion of feed ingredients that have a high environmental impact consumed at an elevated level, particularly corn. This highlights the need for more research into feed ingredients to further enhance the positive environmental effects of new feeding strategies.