Scientists in Nova Scotia are trying to come up with a way to prevent cattle from hosting the toxic strain of E. coli that can make humans sick if they eat meat contaminated with the bacteria. 

Food safety research scientist Martin Kalmokoff, who works at the Atlantic Food and Agriculture Research Centre in Kentville, said the research is trying to figure out why certain types of E. coli multiply in the guts of cows. 

The idea is eventually farmers will be able to feed to young calves a harmless type of E. coli in liquid form, either through a bottle or syringe, that will prevent the more toxic strains from flourishing. 

The hope is the mixture would out-compete the toxic E. coli O157 for space in the gut. 

"If you can prevent the cattle from carrying the organism, it would have obvious impacts in terms of food safety down the production line," said Kalmokoff, who works for Agriculture and Agri-Foods Canada. 

Beef cattle in Amherst

Agriculture Canada researchers have been studying cattle at the Nappan Experimental Farm in Amherst, N.S. (John Duynisveld)

"Essentially you'd like to eliminate the pathogen from cattle completely, so when they go to slaughter you don't have the opportunity of contaminating meat and meat products with this particular product." 

E. coli gets introduced to calves early on, either from their mothers or through barns full of fecal matter. Once a certain strain starts multiplying, it can reside in cattle through the duration of their life, Kalmokoff said. 

E. coli O157 in a cow's digestive tract can contaminate the rest of the carcass during the slaughter process, according to the Canadian Food Inspection Agency.

If that meat makes it to the plate and is not cooked to a certain internal temperature, it can make humans sick. The Public Health Agency of Canada says illness ranges from severe stomach cramping to kidney failure. 

Why some cows and not others?

In western Canada a group of Agriculture and Agri-Food Canada researchers are studying E. coli in feedlot cattle. The research in Nova Scotia is focussed on a herd of cattle pastured at the Nappan Experimental Farm in Amherst and is analyzing bacteria growth in sheep systems as a model.

Kalmokoff said the work has been underway for a year and the goal is to figure out what factors contribute to the bacteria multiplying in the large intestines of cows. 

Once that's established, the plan is to look at ways of edging out the E. coli O157 strain so it would be expelled from the cattle's guts. 

"The question really becomes is it possible to prevent this particular strain of E. coli from being able to colonize and establish itself in a given calf," Kalmokoff said.  

There's no commercial treatment to prevent cows from harbouring E. coli, but Kalmokoff said scientists have used a similar method to successfully exclude salmonella in chickens. 

He said a mathematician will be helping analyze the data gathered in hopes of figuring out what specific factors allow the toxic E. coli strain to take off in some cows and not in others.