As new, more challenging salmonella strains emerge in Canada’s poultry industry, researchers are working with innovative “natural” options to reduce risks to bird health and food safety.

Dr. Hany Anany has been focusing on naturally occurring bacterial viruses called bacteriophages, or phages, for more than 15 years for their ability to effectively target salmonella and other troublesome bacteria found throughout the poultry production and processing chain. He has successfully incorporated these beneficial antimicrobials into packaging materials to create anti-salmonella, phage-based bioactive packaging for raw poultry. Now, he is applying that knowledge to control salmonella in laying hens and is about midway through a five-year research project.

“Phages are highly precise, natural tools that target harmful bacteria like salmonella without impacting beneficial microbes,” Anany says. “With rising antibiotic resistance and strict regulations on antibiotic use in layer flocks, bacteriophages are a promising alternative that could complement other management practices like biosecurity, vaccines and probiotics.”

Anany and his team set out to develop and optimize a phage “cocktail” – made up of four phages – that could effectively control salmonella in laying hens over a wide temperature range. An additional challenge with salmonella in layers is that hens can be carriers without showing symptoms, and the bacteria can colonize the ovaries, creating a risk of egg contamination.

“Using phages to control salmonella in laying hens could help reduce the contamination risk before eggs ever reach the market,” Anany says.

Harnessing viruses for good

Commonly called bacteria eaters, phages are “good” viruses that exist throughout the natural world. They are environmentally friendly, highly specific to the bacteria they control and able to multiply as needed when faced with high levels of their target bacteria.

Phages are found wherever bacteria exist, and those that target salmonella are commonly found where the bacteria circulate in poultry barns.

Anany and his team began this research by collecting and identifying phages that occur naturally in live birds and poultry barns to find ones effective against Salmonella enteritidis, Salmonella Kentucky and other strains with a growing impact on poultry production. They are particularly interested in the broader effects of adding a phage cocktail to layer diets to ensure it targets salmonella without disrupting the natural gut microflora, which is critical for overall bird health and performance.

“We were able to narrow down a large pool of possible phages to a four-phage cocktail that is highly effective against the salmonella strains we are targeting in laying hens,” Anany says. “Phages are specific to the bacteria they attack, so we were able to select the right combination to target the strains that matter most to poultry production.”

The makings of a good cocktail

The phage cocktail must meet key criteria to move successfully from the lab bench to real-world application. First was developing an effective process to encapsulate the cocktail to protect it and extend its shelf life inside the bird – a dry powder spray that coats the phages before being added to feed.

Working in collaboration with AAFC researcher Dr. Qi Wang, the team also needed to show that the mixture could control salmonella at two key temperatures – 41°C inside the bird and 25°C in the barn environment. In addition, it needed to reduce salmonella levels in the bird’s gut without disrupting the natural microflora, while also decreasing the amount excreted onto eggshells and into litter.

The mixture also had to remain effective against resistant strains that may mutate, be hardy enough to survive passage through the bird’s gut and reach colonization sites in sufficient numbers to exert control, and be easy to administer in either feed or water.

Moving to real-world testing

When selecting phages for the cocktail, Anany and his team identified two important traits. There is a clear temperature effect, as not all phages functioned effectively at both temperatures – inside the bird and in the barn – making this a key criterion for practical on-farm use.

They also found that including phages that attach to target bacteria through different receptors is an important resistance management strategy. This approach could reduce the chances that mutating salmonella strains escape control.

“Phages are working well in the lab,” Anany says. “We now want to test whether they can reduce salmonella colonization and shedding in the bird gut, limit egg contamination and be applied in the barn environment to further reduce salmonella levels and risk.”

Anany is collaborating with Dr. Nicole Ricker in the Department of Pathobiology at the Ontario Veterinary College, University of Guelph, to feed the phage cocktail to laying hens this fall. After trials are repeated next year, he says the team will be in a strong position to engage industry partners for scale-up, manufacturing and regulatory planning.

“I want producers to know that we are moving the project toward real-world application so we can fine-tune efficacy, dosing strategies and product stability,” Anany says.

While phage-based products are already commercially available in some countries for food safety and agricultural use, Canada is not yet among them.

Anany says phages offer a targeted, environmentally friendly approach to support bird health and food safety. He envisions a time when a commercial phage cocktail could be available as a dry powder added to layer feed or water during high-risk periods such as flock placement, stress events or other known risk windows.

“A similar approach could also be applied to broilers and turkeys,” he says. “The key is matching the phage cocktail to the bacterial strains most common in each production system.”

This research is funded by the Canadian Poultry Research Council as part of the Poultry Science Cluster, which is supported by Agriculture and Agri-Food Canada through the Sustainable Canadian Agricultural Partnership, a federal-provincial-territorial initiative.

Canadian Poultry Magazine

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