I would assume that its use as a durg would mean you can't just extract from meat animals, similar to the chicken farms whose sole purpose is to provide clean eggs for vaccine production you'd probably have a farm growing cows or whatever specifically to get the epinephrine (if you didn't synthesize it).

That being said, extracting more profit is the name of the game, slaughterhouses absolutely find ways to use all of the animal if it can be done. Why raise a whole cow only to sell the steaks? The offal, blood, bones, off cuts and little bits of remaining meat all have uses. That's why pink slime exists, trying to extract all the meat, even if you've got to sanitize it and press it into nuggets.