More than 41,000 chickens suffocated after power was knocked out at the Cummins Unit's poultry farm, a prison official reported Monday.

A tractor driver hit poles at the farm in August, resulting in a seven-hour power outage, Arkansas Department of Correction Director Wendy Kelley wrote in her monthly report to the board Monday.

"The generator did not operate correctly so there was no ventilation in the houses," Kelley wrote.

The prison farm is moving forward to replace the birds and to install a backup generator, Kelley wrote.