A KIRO Team 7 Investigation exposed how cows, too sick or injured to even walk, routinely get turned into hamburger.

We received a volatile reaction from our viewers and an attack on our report from the federal agency that's supposed to protect your food supply.

VIDEO: Downer Cows Investigation: Part IV>

Investigative Reporter Chris Halsne spent months undercover, videotaping what are known as "Downer" sales.

Downers are cattle that aren't healthy enough to even stand. For months we watched and videotaped USDA meat inspectors repeatedly allowing suspect downers into a slaughterhouse in Chehalis.

The USDA refused to respond to our repeated efforts to show them the tape, and analyze the performance of its veterinarians.

Finally, they sent us a statement, but it's far from apologetic.

KIRO Team 7 Investigators videotaped hours worth of downer transactions at Midway Meats in Chehalis.

We watched while farmers brought their dying cattle to the plant in pick-up trucks and trailers. Since the cows were too sick, weak, or crippled to walk inside, a bobcat and chain helped them move across the parking lot.

"If what everyone saw on KIRO TV is humane, something is very, very, wrong," says Susan Michaels, co-founder of Pasado's Safe Haven, a Monroe-based group that monitors animal rights issues.

She, and many of our viewers, were sickened by the revelations in our hidden camera report, but not surprised.

"We think that state and USDA inspectors are a joke. Their excuse is always there isn't enough money and not enough people around," Michaels says.

One of America's top experts on downer cows is former USDA vet trainer Dr. Lester Friedlander. He watched our tape, and was heavily critical of the lack of proper inspection outside the Midway Meats plant.

"After looking at a tape like this, you ask where do you think fecal contamination comes from? Is this a good source? Obviously, it is a good source, the main source," Friedlander says.

KIRO Team 7 Investigators offered to show several hours worth of unedited tape to the USDA weeks ago, but they refused. Tonight, they finally faxed a response.

"We take allegations of wrongdoing very seriously in all plants where we have jurisdiction. When we find violations, we act quickly with all the enforcement authority we have under the law."

But in next statement attacks the messenger, us.

"Your station repeatedly refused to provide any evidence or even the name of the plant in question, thus completely impeding our ability to conduct an investigation."

That's not true. KIRO 7 has a Freedom of Information Act request, sent to USDA on September 5th, asking for all inspection reports, and condemned cattle tags issued for Midway Meats.

To date, KIRO 7 has not received the information.

KIRO Team 7 Investigators also called, and talked with no less than six federal investigators regarding this matter in the past three weeks.

That includes the special agent in charge of West Coast investigations for USDA in San Francisco.

If you want to comment on the use of downers to Congressional members on the Agriculture Committee, send them an e mail.