By Rod Nickel

WINNIPEG, Manitoba (Reuters) - Ranchers in western Canada whose herds are under quarantine due to the spread of bovine tuberculosis told federal legislators on Tuesday that they desperately need to sell cattle or collect compensation to avoid financial disaster.

Ranchers who raise calves typically sell them in autumn to feedlots, where they are fattened to slaughter weight.

But some ranchers are absorbing the cost of feeding calves longer due to quarantines by the Canadian government on 34 farms in southeast Alberta and two farms in southwest Saskatchewan. The federal Canadian Food Inspection Agency (CFIA) has confirmed six cases of Alberta cattle with bovine TB, dating back to the September discovery of an infected cow at a U.S. slaughter plant.

"The feed costs are going to destroy us," said rancher Ross White, speaking by video to Canada's agriculture committee meeting in Ottawa. "...I'll be broke by spring."

Rancher Brad Osadczuk told legislators that the quarantine is costing him C$92,000 ($68,000) per month to feed 400 head of cattle, one-third of his herd.

Canada's C$10.5 billion ($7.8 billion) cattle industry is centered in Alberta, the biggest cattle-raising province, and home of slaughter plants owned by JBS USA Holdings Inc and Cargill Ltd [CARGIL.UL] [CARG.UL].

Canadian Agriculture Minister Lawrence MacAulay said the government pays compensation for animals that are destroyed, but there currently is no program to help farmers whose herds are under quarantine.

"I’ve asked my department to look into that and try to rectify the situation," he told reporters. "Having been a farmer, I fully understand the cost that's involved."

An estimated 18,000 head of cattle are held in quarantine for testing, Rich Smith, executive director of Alberta Beef Producers, said in an interview. While the quarantines are causing "great hardship" for ranchers directly affected, it is unlikely to have a major impact on overall cattle supplies, he said.

Exports of young cattle from Canada, the sixth-largest beef and veal exporter, to U.S. feed lots have dropped by more than one-third year to date, according to the U.S. Department of Agriculture.

CFIA has said its testing, aimed at tracing the spread of TB, could take months.

Bovine tuberculosis is a contagious disease caused by bacteria that are closely related to the bacteria that cause tuberculosis in humans and birds, resulting in illness, coughing and death, according to the World Organization for Animal Health (OIE).

($1 = 1.3464 Canadian dollars)

(Additional reporting by David Ljunggren in Ottawa; Editing by Dan Grebler)