The report released Monday by the Government Accountability Office said that feeding and caring for the captive horses cost $21 million in 2007, or about 75 percent of the entire budget of the wild horse and burro program, The Salt Lake Tribune reported. In 2001, the Bureau of Land Management spent $7 million on the captive horses.

The GAO also suggested that the BLM may be breaking the law by refusing to sell animals for slaughter because of fear of the public reaction to killing healthy animals. There was a massive outcry in June when Henri Bisson, the BLM deputy director, said that 6,000 animals should be killed to get herds to sustainable levels.

The wild horses are descended from domestic ones brought to North America by European settlers.