Agents from the Maine Animal Welfare Program donned bulletproof vests and armed themselves with shovels and a backhoe Wednesday to go to a Swanville farm and exhume the carcasses of at least three pigs buried on the property. The agents wore protective clothing because cases of alleged animal neglect can become tense and emotional, according to Liam Hughes, the director of the state’s animal welfare program. He said that the activity in Swanville was part of an ongoing animal abuse investigation at Ireland Hill Farms, which is owned by Jerry and Emily Ireland.