OTTAWA -- Canada's food safety organization says two cows discovered to have mad cow disease in the last five years were born on the same Alberta farm.

Paul Mayers of the Canadian Food Inspection Agency said the most recent case detected earlier this month involves a cow born in 2009.

Another cow born on the same farm in 2004 tested positive for the disease in 2010, Mayers said. No parts of the cows got into human or animal food, the agency has said.

"At this time it would be purely speculative to suggest that because this case was born on the same farm as the previous case that there is some additional risk factor link," he said on Friday.

Mayers said the current investigation will include tracking 750 animals in the same birth cohort, which includes cows born before and after the infected animal.

He added investigators will also look at all the cows born on the farm between 2004 and 2010 which may have been exposed to the same feed.

"The feed cohort is of course larger," he said. "The focus of our feed investigation will include consideration on whether any non-compliance with respect to the feed ban may have contributed to this case.

"The scope of the investigation is broad," he said.

Mayers said it's the first time Canada has had two cases of mad cow disease linked to the same birth farm. It is also the first case detected in a cow in four years, he said.

Officials said China is the latest country to impose temporary trade restrictions on beef imports from Canada, joining Taiwan, Peru, Belarus and South Korea. Indonesia has also suspended imports of non-edible bone meal.

Mayers has said the case in Alberta has been reported to the World Organisation for Animal Health and won't affect Canada's official beef trade status.

"Canada's suite of internationally recognized safeguards effectively protects the safety of food and animal feed," he said.

Canada's chief veterinary officer, Dr. Harpreet Kochhar, said there was a comprehensive investigation into the 2010 case.

"We did a very thorough analysis of that particular feed cohort," he said. "The investigation actually concluded there wasn't one specific cause that could have been pointed out."

He added one possible factor could have been cross-contamination of feed, but Canada has since instituted an enhanced feed ban and improved surveillance measures.

"We are actually much more equipped," he said.

He said since 2005 more than 430,000 cows have been tested for mad cow disease.

A case of bovine spongiform encephalopathy in 2003 at an Alberta farm devastated Canada's beef industry. About 40 countries closed their borders to Canadian cattle and beef products, although most of those markets have since reopened.