Whatever the federal government's case against Rancho Feeding Corp., the U.S. Department of Agriculture has done a poor job of explaining itself, according to both North Bay ranchers and national food safety experts.

The USDA's lack of communication has left the public guessing at the risk it faces from a year's worth of recalled beef that was killed and processed at the company's Petaluma plant. Since a large amount of that 8.7 million pounds of beef was prepared on a custom basis, the official silence has left individual ranchers and meat purveyors to insist the products their customers purchased were untainted.

"The USDA needs to do a better job of communicating," said Sarah Klein, a senior attorney on food safety for the Center for Science in the Public Interest in Washington, D.C. "There must be more that they can provide even while trying to protect the integrity of their investigation."

For their part, local ranchers have complained they are being forced to surrender beef to a recall even as the government provides them few details.

"It's really hard to have this happen with no explanation, knowing our animals were very healthy," Freestone Ranch owner Susan Brady said last week.

In the absence of official statements from Rancho and the USDA, local ranchers are trading rumors and speculation about what happened. Some suggest that Rancho simply failed to file proper paperwork when it turned away sick cows, while others wonder if there were more serious lapses.

An area of much discussion has been the nature of the cattle at the center of the investigation. Were they older dairy cows, who like humans, typically become more susceptible to disease and health problems as they age? Or do the government's concerns extend to other animals?

"They say there are diseased animals, but what do they mean?" asked Michael Hansen, a senior scientist in New York for Consumer's Union, the policy and advocacy division of Consumer Reports magazine. "We need to know."

The USDA's silence, Hansen said, is causing "collateral damage" to all the ranchers who processed healthy cattle at the Rancho plant last year.

Asked for a response to that question and other matters, a USDA spokesman in Washington last week said the agency would have no comment because of the ongoing investigation.