Composting is a valuable tool for dealing with food-based organic matter, but is it always the best use? The reality is that food waste can have value. While composting is one way to create value, another approach may be in creating poultry feed. 

Three studies conducted by researchers at two Canadian universities reviewed options for disposing and upcycling of food waste with focusing on offsetting costs by converting that waste into an input for other forms of food production. 

Bringing value to waste

Shaiyan Siddique, a PhD student in the Interdisciplinary Graduate Studies Sustainability Program at UBC and a member of UBC’s Food Systems PRISM Lab in Kelowna, conducted two related studies to review different options for converting food waste into viable feed. 

“This study comprised of a literature review of cases from across the world that used the life cycle assessment approach to assess the environmental sustainability implications of food waste to animal feed valorization systems,” Siddique says of the first study. 

He notes that life cycle assessment (LCA) is the “most popular approach” in the agri-food sector to consider environmental impacts and benefits of potential technologies. 

This literature review included 27 research articles which reviewed a variety of food waste inputs (primarily mixed food waste from households, supermarkets, restaurants and other food service operations) and technologies to go from waste to feed. The stages of waste processing included steps like collection, sorting, grinding and drying. 

“Amongst the key findings was that countries such as Japan and South Korea are already pioneers in food waste to feed valorization and that such technologies hold a lot of potential for similar application countries such as the US and Canada,” he says. 

Learnings from Pennsylvania

The second study used LCA to assess the environmental performance of a commercial-scale Pennsylvania facility which converts grocery food waste to laying hen feed. This valorization process is automated through the processes of sorting, grinding, cooking, centrifuging and drying. 

“We found that including their product in laying hen feed could reduce the carbon footprint of eggs by about 17 per cent,” Siddique says. “Researchers at North Carolina State University found that a five per cent inclusion rate best supported hen performance.”

Everyone would do it if it were easy

The benefits are likely obvious: food waste in landfills is common and produces methane gas, and reducing reliance on commercially produced, traditional livestock feed. To fully appreciate the benefits of food waste valorized as poultry feed, environmental assessments of food waste to feed pathways should include the prevention of landfill emissions. 

It certainly sounds like a win-win situation; however, despite the benefits, the challenges are far from insignificant. Disease transmission and energy consumption are two of the main hurdles to bringing food waste to the poultry barn. 

“There is an obvious concern surrounding the spread of prion diseases in ruminants (such as mad cow disease) originating from feeding animal origin products,” he says.

While feeding animal-origin food waste to ruminants is banned in Canada and the European Union, it is commonly done with poultry. 

“Studies have found no evidence of prion disease affecting non-ruminants such as poultry and pigs,” Siddique says. 

“In fact, the inclusion of food wastes may actually improve the egg-laying performance of layer hens.”

But conventional feed supplementation is needed because the waste-converted feed is not complete enough for monogastric species like chickens

“More feeding trials are needed to optimize the inclusion rates for such feed inputs,” he says.

Energy use to convert food waste to valorized feed through drying is a key hurdle. Siddique suggests central regions within cleaner energy grid areas like Vancouver, BC and Montreal, Quebec could be potential options for food waste valorization facilities with centralized transportation access.

“Drying the valorized feed product is an energy-intensive process and contributes most of the resource, environmental impacts of such a system,” he says. 

Appreciating further challenges

Japan and South Korea may be considered pioneers in the valorization of food waste, but differing regulations and practices for poultry in other countries, like Canada, may hinder the application of information from these leaders. Because six of the seven commercial-scale studies reviewed are from Asia, functionality in North American farming may be challenging.

“Working with CFIA for regulatory approval should be undertaken by companies aiming to market valorized food waste-to-feed products,” Siddique says. “Farmers will need to communicate with their feed producers and feed nutritionists about sourcing and incorporating valorized food waste products into their feeds and monitoring their herds/flocks accordingly.” 

He feels there is promise for food waste to poultry feed options in North America. 

“We have already seen an example of it at commercial scale,” he says. “It is also important to understand people’s perspectives on food waste and raise awareness about the benefits of such a system to ensure a sustainable and viable business prospect.”

Beyond mixed waste

The third study is that of Xujie Li, a post-doctoral fellow at Dalhousie University. In potato processing regions like Atlantic Canada, potato peels are abundant. Together with his supervisors, associate professors, Stephanie Collins and Bruce Rathgeber, the study was able to consider how potato peel meal might be beneficial in poultry diets.

But peels also contain a decent nutrient profile. The scientist says there is 13 to 18 per cent crude protein, 40 to 50 per cent fibre and a significant amount of potassium, zinc and iron. 

“We just want to investigate if the potato peel can be used as an alternative nutrient source without jeopardizing the health of the broilers,” Li says. 

The researchers conducted two studies with different broiler producers each time. The first was straightforward with chicks getting either a 10 per cent inclusion of the dried potato peel or not getting the potato peel meal. Birds given the meal were also given a blend containing seven types of enzymes to aid in digestion, but the result was poor. 

At the 10 per cent inclusion rate, the birds’ feed consumption dropped. 

“They didn’t like it as much,” says Li. “The difference in body weight [compared to the control birds] was quite obvious.”

Enzymes and early feed

“For the second study we asked for a different enzyme product,” he says. “Higher cellulase, galactanase and glucanase. If the birds are given something to help break down the increased fibre, it is beneficial.”

In this study, there were eight groups of chicks. The first four were: the control diet; five per cent potato peel meal inclusion in their diet; five per cent inclusion plus the new enzyme; and 10 per cent inclusion plus the enzyme. The fifth to eighth group were the same, but these chicks were given food and water during the transportation process for approximately four hours. 

The results were telling. Birds with standard starter feed during transport had lower (nearly half) corticosterone levels post-transport .

“Giving chicks the access to feed and water during the transportation improves the body weight and reduces the stress,” he says. “It has a long-lasting impact on the bird’s performance.” 

Throughout the study, birds given the five per cent potato peel meal and enzyme treatment saw statistically higher feed conversion ratios than birds in other feed groups. 

“Right now, we are having a positive outcome from the study,” Li says. 

Waste not, want not. The practices of ancient farmers who tossed food scraps to chickens are getting a technological twist that has potential for how birds grow and thrive. 

Considerations of food waste valorization

Theoretically, making use of food waste in the poultry house is a viable solution. However, the review of existing studies about the practice found that more than half (56 per cent) made use of theoretical information. 

Other considerations include:

• Few studies reviewed had comparable processes and methods
• Technological needs and readiness information was not included in most studies
• Regulations in Asia (where six of the seven commercial-scale studies were conducted) are vastly different from those in North America
• Processes to valorization are energy-heavy with the drying process contributing up to 94 per cent of Global Warming Potential (GWP)

 Potato peel meal in poultry diets

Regardless of whether potato peel meal is fed or not, early feeding during transport is a key driver of chick health and wellness. If potato peel meal is included, insights include:

• Enzymes are essential. Potato peel meal will have a negative impact without tools to break the fibre down.
• Negative impacts can include substandard weight gain, less food consumption and significantly larger gizzards and intestines.
• Including an enzyme more specific to potato peel saw great feed conversion and greater weight gains in birds when five percent potato peel meal was included in the feed.