A federal judge has postponed opening the Canadian border to cattle trade Wednesday because of concerns of the risk of introducing mad cow disease to U.S. cattle.

Ranchers-Cattlemen Action Legal Fund, United Stockgrowers of America filed a lawsuit in January against the U.S. Department of Agriculture, seeking to keep the border closed to cattle trade. The complaint states the USDA’s decision to open the border to trade with Canadian beef and cattle younger than 30 months of age will increase the risk of bovine spongiform encephalopathy, or mad cow disease, infecting U.S. herds. Mad cow disease does not generally manifest itself in cattle younger than 30 months of age.

U.S. District Judge Richard Cebull granted a temporary court order to keep the border closed and told attorneys for R-CALF and the Department of Agriculture to prepare for a trial.

“In general, our lawsuit says the United States has not conducted the scientific study that needs to be done to determine the actual risk of opening the border,” said Bill Bullard, chief executive officer of R-CALF USA.

Bullard said R-CALF has recommended several measures need to be taken, like increases in Canadian testing, before trade can resume.

Roger McEowen, associate professor of agricultural education and studies, said Canada does significantly less testing of cattle for mad cow disease than any other country at risk for the disease.

In a published response to R-CALF USA’s complaint, the Animal and Plant Health Inspection Service said “testing apparently normal animals presented for slaughter is not an effective use of the tests … and provides no assurance of food safety.”

Bullard said the most recent cow infected with mad cow disease in Canada, discovered Jan. 11, was almost 7 years old.

The cow was born after the a feed ban was put in place in Canada prohibiting feeding bone meal and similar animal products to livestock.

“That clearly demonstrates that Canada had a break in its system,” Bullard said.

Nolan Hartwig, professor of veterinary diagnostic and production animal medicine, agreed strict adherence to the bans is important for a safe market.

“That has to be a lock-tight system,” he said.

Although proponents for a closed border identify Canada as high risk, according to guidelines set by the Paris-based World Organization for Animal Health — a group that sets health standards for the international trade of animals — Canada is actually at minimal risk for mad cow disease.

Bullard contends that Canada was “misclassified” by the organization and believes Canada is a moderate-risk country, which is why he said U.S. trade will be affected by opening the border.

“We will further diminish consumer confidence, particularly our export consumer confidence, in the safety of U.S. beef,” Bullard said.

He said unwillingness of some international export markets to resume trade with the United States shows that other countries, not just American cattlemen, are concerned about the USDA’s decision to open the border. Japan and other markets closed their borders to U.S. beef in December 2003.

Sen. Chuck Grassley, R-Iowa, said in a conference call Tuesday that he thinks it is important to open the border, provided safety measures are in place. He said if the United States is asking Japan to open its border, the same should be done for Canada. Hartwig said the benefits of opening the border could extend to the beef markets in both Canada and the United States. He said Canada’s market was “absolutely decimated” when the border closed, and the U.S. market also felt a pinch, particularly in the dairy market.

— The Associated Press contributed to this article