Animal Farm Anti-Sudoku

The Sudoku grid has been divided into 16 pentominoes, with one extra cell remaining. Each animal type has a different pentomino shape, and there is one of each animal, except the pigs. The sum of the digits in each pentomino is the same. There is a region that the pigs only allow pigs to enter. This region is 16 orthogonally continuous cells. Inside this region, sudoku rules do not apply. In other words, if the numbers in these 16 cells are removed, normal Sudoku rules would apply to the rest of the puzzle. Find the pigs.