A recent discovery that modifying one gene restores regeneration to mice. I love the story behind this, as the scientists discover the effect accidentally, as mice that have been notched in the ear to track them in the experiment regrow the missing part, and thus, become difficult to track.
Now, imagine if the same regenerative capabilities were afforded to pigs, cattle or chickens. Imagine being able to harvest just the sirloin or bits of hangar steak or breast meat - again and again and again, as the animal regrows the missing parts. Gruesome, maybe. But conceivable.