MADISON, Wis. (AP) — The state Department of Natural Resources' board has unanimously approved an emergency rule that requires deer farms to upgrade fences in an effort to slow chronic wasting disease.

The rule calls for deer farms that have had a CWD infection to install a second fence or solid barrier. CWD-free farms would have three options: add a second fence, add a solid barrier or add an electric fence. Farmers would have a year to comply.

According to the DNR, 13 farms have had a CWD infection. The agency estimates those farmers would have to spend about $876,365 to comply. The cheapest option for remaining farms is electric fencing. The DNR estimates that would cost $1.3 million.

The rule also imposes a general ban on movement of deer carcasses from CWD-affected counties.