In Canada and the United States. driven by fears over antibiotic resistance that might spill over into human therapies, there has been ongoing pressure to reduce the amount of antimicrobials used in livestock feed.

Dr Alan Mathew, the Head of Purdue University's Animal Science Department, says bacteriophages present an interesting option.

Dr Alan Mathew-Purdue University

They are viruses that specifically attack bacteria.

They are much smaller than a bacterium, they attach to bacteria, they kill them, they degrade the membrane killing the bacteria and actually they force the bacteria to make more phages so it's kind of a revolving door so to speak and the phage populations can expand rapidly.

They're very specific for certain strains of bacteria so they won't work on other pathogens but we can create these phage cocktails of different phages that will have a broader spectrum across pathogens and they have been shown to be effective when used in pig feed in reducing salmonella.

They've also been shown to be effective when they are put on post-harvest foods and they can keep the food-borne pathogen populations in check.

The limitations of phages is that they, at this point, are a little bit expensive to produce in large quantities.

There are commercial companies that are looking to expand upon that and find ways to produce them more economically.

The great thing about phages is that they are everywhere so the governing bodies that look at the risks of these products consider them as generally regarded as safe so they have no downside to humans at all.

They specifically attack bacteria.

Dr Mathew says these phages are found everywhere that there are bacteria, they've always been around us, they don't need to be modified and they are very safe.