But the groups are fighting the court order that requires the money to cover potential losses by the slaughterhouses should the organizations ultimately lose their lawsuit.
Attorneys for the Humane Society of the United States, Front Range Equine Rescue, Marin Humane Society, Horses For Life Foundation, Return to Freedom, and others argue the bond should not be required because their case is against the federal government and its permitting process, not the companies that were recently given permission to begin slaughtering horses.
The groups last month won a temporary restraining order to halt plans by Valley Meat Co. of Roswell, N.M., and Responsible Transportation of Sigourney, Iowa, to open their plants this month. They were then ordered to post the bond by Friday.
Earlier this week, Responsible Transportation said it was dropping plans to slaughter horses and would convert its plant to cattle in light of the temporary restraining order.
The Iowa company's president, Keaton Walker, said his firm cannot afford to wait for more court deliberations. Valley Meat Co., however, which has been at the fore of the fight, has vowed to stay the course. The company has been pushing for almost two years for permission to convert its cattle plant into a horse slaughterhouse.
Valley Meat co. owner Rick De Los Santos said his decision to convert his small slaughterhouse to horses was made after his market for cattle dried up when a number of dairies shut down in southeastern New Mexico.
The case has sparked an emotional national debate about whether horses are livestock or companion animals and how best to deal with the tens of thousands of wild, unwanted and abandoned horses across the country.
Horses were slaughtered domestically for decades until Congress cut funding for inspections for horse plants in 2006. That funding was restored in late 2011.