So far, 156 of the 983 horses gathered in late August and early September from the Jackson Mountains in northwest Nevada have died or been euthanized, said BLM spokesman Doran Sanchez.

The BLM voluntarily closed the center in Palomino Valley about 20 miles north of Reno on Sept. 26 after 130 animals had died. Officials said closing the facility to the public was a preventive measure because salmonella bacteria found in some of the mustangs can infect people and domestic animals.

The center's 160 acres of corrals serve as a national holding facility for up to 1,650 animals the BLM rounds up from public rangeland to be vaccinated and marked while awaiting shipment under the agency's wild-horse adoption program.

Officials say the horses were unhealthy when they were rounded up. Many were extremely thin and weak because of a lack of food and water caused by drought.