Enrollment in the dairy Margin Protection Program (MPP) de­­clined in 2017, as dairy organizations and lawmakers continue to look for fixes in the program to offer more income safety net protection for milk producers.

The MPP program, which was launched as part of the 2014 farm bill, will cover farms producing 138 billion pounds of milk in 2017, or 64 percent of projected U.S. milk production. That’s down 13 percent from last...