ST. PAUL, Minn. (AP) - The state Board of Animal Health says it will expand a zone in northwestern Minnesota that's being heavily regulated because of bovine tuberculosis.

Starting April 15, producers with cattle and bison herds in the larger area will have to get movement certificates. They'll also have to individually test most animals before moving them.

Producers in the area must also test their whole herd each year and have an official risk assessment on interaction between deer and cattle.

The new area includes parts of Roseau, Lake of the Woods, Beltrami and Marshall counties.

The Board of Animal Health says the change gives a buffer around the area of concern. Officials say it also could help the state as it asks the Department of Agriculture for "split state status" that would lift restrictions on the majority of the state's producers.