98:19 If a person slaughtered a bird for food and it was found to be unkosher, it may not be handled, the same as with any other muktzeh. However, if a person slaughtered an animal and it was found to be unkosher, he may stash the carcass in a place where it won't be ruined. If this is not possible, he may sell it to a non-Jew so long as he doesn't fix a price or weigh it. One might also be lenient with fattened geese, which are frequently found to be unfit.
98:20 One should only slaughter an animal on yom tov in a case of great need. It is forbidden to sell the meat by weight or to fix a price; rather, he just gives the customer a portion “as is” and he gets paid after yom tov.