Canada's food safety watchdog says it won't begin tests to find the source of a bovine tuberculosis outbreak until the fall.

The Canadian Food Inspection Agency wants to focus on how the disease managed to get onto one Alberta farm and infect six cattle, said Dr. Harpeet Kochhar, the agency's chief veterinarian.

"While we have focused extensively on the potential for the spread of disease so far, we are now turning our focus to tracing activities to identify the source of the infection," he said Friday.

"Testing of herds identified through tracing activities will begin in the fall because calving season has already begun in Western Canada."

The CFIA said 51 farms in southeastern Alberta and seven in southwestern Saskatchewan remain under quarantine pending the results of tests to see if the disease has spread from the infected farm.

Initial test result evidence suggests there is a low risk of the disease spreading, he said.

An estimated 10,000 cattle destroyed

The destruction of about 10,000 cattle linked to the infected herd will also eliminate some of the risk.

So far the agency has paid $11.2 million in compensation to producers.

The federal and Alberta governments have also paid producers about $3 million to help feed and care for about 28,000 cattle that have held under the quarantine.

Some ranches have been locked down since October.

Kochhar said farms where cattle have been destroyed will soon be able to be cleaned and disinfected so producers can buy replacement cattle.

The investigation into the source of the TB could run into next year.

The agency said nailing down what caused the outbreak is important to Canada's beef export trading partners.

But Kochhar admitted investigators and testing may come up empty-handed.

"We may never find a source," he said. "We will continue to do the investigation in a very diligent fashion so that we can demonstrate to our trading partners that we are doing a thorough job and there is no impact on our market access."