KALAMAZOO, Mich. (AP) – A union has filed a grievance in response to Western Michigan University’s hiring of goats to clear 15 acres (6.07 hectares) of woodland on campus.

The Kalamazoo Gazette reports that Kathi Babbit is the chief steward of the American Federation of State, County and Municipal Employees local union. Babbit wrote in a July newsletter that the grievance had been filed in relation to subcontracting and the unreported use of goats.

The university hired the team of goats after a half-acre trial run last year. Officials of goat rental company Munchers on Hooves say the animal consumes 3 to 5 pounds (1.36 to 2.27 kilograms) of vegetation per day and leaves behind natural fertilizer.

University spokeswoman Cheryl Roland says that no school workers have been laid off by the goat project.