Occupational portrait of twenty-seven men outside an abattoir(?)

A little over 6.5 x 8.5 inches, mounted on 10 x 12 board, which has a 1.5 x 1 inch loss at the lower left corner. Fair with heavy soil and creasing, footprint on the verso; image faded but retaining detail. Occupation/industry unknown, possibly an abbatoir? Several men have aprons, shin coverings, and what look like double-handed carcass splitters. On the other hand, a few other men in the back row just have cartoonishly poised pipes (two almost look like twins).