Be careful not to knock it out to reset its taming efficiency too many times (I did it three times as I could not find out which button on PS4 I had to press to feed it while riding) as this will quickly starve the unicorn, killing it. Even if it is starving you still have to wait a large interval before feeding it again as well, so don't try to starve it.

More Unicorn Taming & KO Tips