I raise non-kosher animals (rabbits) primarily for manure for my garden and fur for clothing. I give the meat away to non-Jews. I understand all domesticated animals are to be humanely killed, regardless of intended use, if killing is called for. Is there a prayer to say before dispatching, even though I am not a trained shochet?
Kosher slaughter is not simply any humane method of slaughter. It is a specific procedure, with precise details that must be followed.
One does not need to follow this procedure when slaughtering animals for most non-food purposes, including clothing. However, you should slaughter the animal humanely, becaue there is a separate prohibition against causing unnecessary pain to animals.
One does not make a blessing if they are not following this procedure.
There is a rabbinic prohibition against dealing in non-kosher food, but it is allowed if the non-kosher food is a side-effect of the business. One example of this is that when Kosher slaughterers inspect animals after they kill them, any animals found to be non-kosher are sold to non-Jews.