Valley Meat sued the department to force inspections, saying it had a legal obligation to do so if a plant met federal standards. While that case is pending, the government will inspect slaughterhouses that comply with technical requirements after its inspectors complete necessary training, according to an e-mailed statement from the USDA recently.
A. Blair Dunn, attorney for Valley Meat, said the plant could begin slaughtering in the next three weeks. Most of the meat will go to other countries, though selling to U.S. customers isn't prohibited, he said. Many of the horses the Valley Meat plant will slaughter would have been shipped to Mexico, about 200 miles away, Dunn said.
Lawmakers including Sens. Mary Landrieu, D-La., and Lindsay Graham, R-S.C., have introduced bills to ban U.S. horse killing for human consumption and prohibit transporting the animals elsewhere for slaughter.
"Horses have been raised for sport, transport, security and companionship, but never for slaughter and consumption," Landrieu said in a recent statement on her website. "There are very few regulations on the drugs given to horses, and we cannot risk introducing dangerously toxic meat into our food supply here at home or abroad."
Opponents say horse-slaughter plants have unusually bad health effects on the surrounding community, with more leftover blood and offal than other slaughterhouses. Valley Meat itself came under scrutiny for poor practices while slaughtering cattle.
Government documents obtained by Front Range Equine Rescue, a Larkspur, Colo.-based horse-protection group, report maggot-infested piles of decaying animals as high as 15 feet on the property.
State inspectors cited Valley Meat in 2010 after finding evidence that animal carcasses had been improperly disposed of at the site, according to a summary from the New Mexico Environment Department. The company paid a $5,000 fine and removed the waste while disputing many of the reported infractions, Dunn said.
Under its settlement with environmental officials, Valley Meat is no longer allowed to compost animal waste on site, said Jim Winchester, a spokesman for the environmental department.
Agricultural organizations such as the American Farm Bureau Federation and the National Farmers Union, the two biggest U.S. farmer groups, support domestic horse slaughter.
Farms and ranches need to be able to have animals slaughtered, said Mike Spradling, president of the Oklahoma Farm Bureau. Along with cattle and pecans, his Flying G Ranch just west of Tulsa's suburbs has about 40 horses, managed by a daughter with a degree in equine science, he said. Horse owners near cities may not be able to bury animals on their land because of zoning codes; rendering facilities may not be available. Without slaughterhouses, horses may be abandoned or mistreated, he said.
"I've heard of horses just dropped off in the desert to starve," he said. "Ultimately, our horses are our private property, and we need to be allowed to have options to care for them."
As for the safety of eating horses, Spradling says any meat slaughtered for domestic consumption will be governed by U.S. food-safety regulations.
Sappington, of Valley Meat, says the plant is getting calls from around the world: "We had people calling from Canada, Russia, Belgium," asking whether the plant may be able to ship them horse meat, he said.
Sappington said he consumes horse meat two to three times a week, often serving it to curious guests, who he says always love it. He grills it, makes hamburgers and -- his favorite -- makes chicken fried steak.
"Anything we've ever made with meat, we've made with horse," he said.
Derek Wallbank contributed to this article from Washington.