Editor’s note: In the Sept. 18/25 Swine & U column, Dr. Gerald Shurson described the issue of food waste and whether we can improve sustainability of food animal production systems by recycling food waste into animal feed.
Food waste disposal options have been characterized in a hierarchical order of priority based on achieving the greatest value from resource recovery while minimizing negative impacts on the environment. The best solution and highest priority are to minimize or eliminate food waste, followed by redistributing food to hungry people.
The next greatest priority is to convert food waste into animal feed — which is preferable to composting, anaerobic digestion to produce biogas, and disposal in landfills. Food waste has been fed to pigs in every country for centuries; but since 2001 it has been banned in the European Union due to illegal feeding of uncooked food waste, which was associated with the foot-and-mouth disease outbreak in the United Kingdom.
Concerns about pathogen transmission as well as an abundant supply of relatively low-cost corn and soybean meal in the United States has also limited feeding food waste to pigs, which has been banned in 18 states. In contrast, Japan (2001), South Korea (1997), and Taiwan (2003) have developed tightly regulated policies and invested in substantial infrastructure using adequate thermal processing to promote the conversion of 35–43 percent of food waste into animal feed.
The wide disparity in government policies among countries regarding recycling of food waste into animal feed has severely limited the ability to reuse the valuable nutrients, reduce negative environmental impacts, and improve sustainability of pig production in the United States and the European Union (which produce much greater quantities of food waste than Japan and South Korea). Furthermore, these Asian countries have demonstrated during the past 20 years that biosafety risks can be adequately managed.
Now that social and consumer pressure is increasing to produce food with a lower carbon footprint and conserve resources, recycling food waste into animal feed needs to be revisited as a viable option in all countries around the world if adequate biosafety processes can be implemented and regulated.
Comparison of alternative disposal methods
Although recycling food waste into animal feed is a higher value alternative with fewer negative environmental impacts than composting, anaerobic digestion, and landfill disposal, it is surprising more comprehensive and comparative studies of disposal methods have not been conducted.
Nine published studies which compared the environmental impacts of using food waste as wet or dry animal feed with the alternatives of anaerobic digestion for biogas production, composting, incineration, and landfill were evaluated.
In general, results from these studies show greater environmental benefits from using food waste as animal feed compared to the other disposal alternatives, but have mainly focused on estimating impacts on global warming using greenhouse gas (GHG) emissions as indicators, with limited evaluation of impacts on the use of such resources as energy, land and water.
One key finding of these studies was the nutritional composition of food waste sources affects the extent of GHG reduction. Nutritional composition also determines whether recycling a specific type of food waste into animal feed was the most beneficial option.
For example, Eriksson et al. showed bread waste had the greatest potential for reducing GHG emission, followed by chicken, beef, and bananas, with lettuce having the lowest potential. These results suggest that food waste sources which contain high energy and dry matter content are more suitable for use as animal feed than less nutritionally dense sources.
Globally, about 6 billion tons of feed (dry matter basis) is consumed by food-producing animals annually; of which, 72 percent is comprised of roughages consumed by ruminants (i.e., cattle, goats and sheep).
Of the 1.57 billion tons of grain, grain by-products, and oilseed meals consumed, 65 percent (about 1 billion tons) are fed to swine and poultry. To put this in perspective, more than 1.3 billion tons of edible food material is wasted annually around the world, which is 3 million tons more than the global consumption of all cereal grains, by-products and oilseed meals by swine and poultry combined.
In addition, about 60 million tons of rendered animal by-products are produced annually from the global meat processing and animal production industry. Therefore, there is tremendous opportunity to recycle energy and nutrients from various food waste sources into animal feed — especially for swine and poultry, because they are unable to efficiently utilize fiber in roughages and require diets which are more energy- and nutrient-dense than those for ruminants.
By repurposing a greater proportion of food waste into animal feed, there would be much less pressure on land and water use for agricultural purposes, as well as less dependence on global crop production for animal feed. In fact, zu Ermgassen et al. estimated if the European Union were to adopt regulated and centralized systems for safely recycling food waste into animal feed (similar to those being used successfully in Japan and South Korea), it would result in a 21.5 percent reduction in land use (1.8 million hectares) for EU pork production.
Furthermore, if 39 percent of the total amount of food waste in the EU was used in pig feeds, it could replace 8.8 million tons of edible grains currently fed to pigs. This is equivalent to 70.3 million tons of annual cereal consumption by EU citizens.
These conservative estimates do not include the additional benefits from processing and using more rendered animal by-products in animal feed, but they clearly show the enormous potential to improve recovery of energy, nitrogen and phosphorus by diverting these valuable resources toward feed use in food animal production systems.
As described in this review, there is enormous potential to significantly contribute to achieving the UN Sustainability Development Goals of responsible consumption and production, reducing climate change impacts, improving life below water, and improving life on land by repurposing food waste streams from pre-harvest to post-consumer stages of supply chains.
Although there is ample justification and incentive to do this, government policies and regulations must be reformed using a more holistic approach. This will mandate recovery and recycling of greater amounts of valuable nutrients from various food waste streams into animal feed. Governments could provide economic incentives or initial subsidies to encourage entrepreneurs to develop the necessary modern infrastructure to facilitate collection, provide adequate capacity and modern thermal processing equipment to ensure biosafety of dehydrated waste streams and create market channels which connect these supplies with commercial animal feed manufacturers.
As the global animal feed industry continues to evolve toward sourcing and using feed ingredients with high nutritional value and low environmental impact, additional life cycle analysis determinations are needed for various sources of dehydrated food waste and rendered animal by-products.
However, additional animal nutrition studies are urgently needed to develop accurate prediction equations of various food waste sources for swine and poultry, to encourage animal nutritionists to fully capture the nutritional and economic value of food waste sources when formulating nutritionally adequate and cost-effective complete animal feeds.
Furthermore, new risk assessments should be conducted, and extensive biosecurity protocols should be developed based on best biosafety practices — especially for pathogenic viruses — to minimize risk of pathogen and prion transmission through processed food waste sources used as animal feed.
Finally, governments, citizens, entrepreneurs, and all sectors of food supply chains need the courage to build food waste collection and processing infrastructure which is economically and environmentally sustainable, using life cycle assessments as well as regulated and certifiable biosafety conditions to create a new model of food sustainability.
Swine & U’s “Food Waste” parts I and II were excerpted from “What a Waste— Can We Improve Sustainability of Food Animal Production Systems by Recycling Food Waste Streams into Animal Feed in an Era of Health, Climate, and Economic Crises?” by Gerald C. Shurson, published in sustainability, Aug. 30, 2020.
Dr. Gerald Shurson is a Professor of swine nutrition in the University of Minnesota Department of Animal Science and can be reached at email@example.com.