The nearly 9 million pounds of beef recalled from a California slaughterhouse this month may have come from cows sick with cancer, inside sources are now claiming.Rancho Feeding Corp., currently under investigation by the U.S. Department of Agriculture after inspectors demanded the processing plant recall a year’s worth of beef, was allegedly purchasing dairy cows sick with eye cancer, decapitating them to hide the disease from inspectors and illegally selling the beef, an anonymous source told the San Francisco Chronicle."Rancho, we're told, was slaughtering them, somehow after hours or in other ways where the inspector didn't know about it," the source revealed. "Because the carcass looked good, (Rancho) mixed it back in with other beef that it sold under its label."USDA officials do not comment on ongoing investigations, and Rancho’s lawyers have forbidden employees from speaking to the media.Bill Niman, the former owner of Niman Ranch who is widely considered a pioneer of humane and sustainable livestock farming, processed his cattle at Rancho and subsequently had his entire 2013 output recalled, even though he says his product was totally separate from the tainted meat in question. Based on conversations he had with USDA officials and others in the ranching community, he also speculates the plant may have been processing cows with eye cancer, noting that it is one of the only facilities that slaughters retired dairy cows, which are often in poor health."A farmer sends a cow in with cancer, and he knows it has cancer-eye -- it's a growth on the eye, this is not a microbial situation," he told the Village Voice. "The inspectors, they know it has cancer-eye. So the farmer shouldn't have sent it, and the inspector should have caught it."An unnamed federal food inspector at the plant also cited a breakdown in responsibility, alleging that the supervising USDA veterinarian ignored her warnings against slaughtering some cows during a five-month period last year.“She would tag animals for the PHV (public health veterinarian) and what she thought sometimes were cancerous, the vet would pass … And she can't question the vet,” Paul Carney, president of the federal meat inspectors union, told the Santa Rosa Press Democrat.But amid all of this, no one has reported getting sick from the meat, and experts say cows with eye cancer are not necessarily dangerous to eat unless the cancer has spread to other organs."If I'm out on top of Mount Everest and have a cow (with eye cancer) and I'm hungry, I'm going to cook her well and deal with getting down the mountain," James Cullor, professor of population health and reproduction at the School of Veterinary Medicine at the University of California, Davis, told the Chronicle. "But if I'm here in this country, I will choose to not consume the animal. I wouldn't feed the animal to my grandchildren."