I hear alot of folks worrying about 2-3-4 week old fawns not accepting the bottle. It is my experience that the fawn may not like you putting it in their mouth, but a hungry fawn will eat, regardless of age. Re-habbers get fawns of this age all the time and they manage to get them sucking.....how come they can do it and we do not seem to believe we can? The remnants of Xylazine and Tolazine or Yobine are residual for 21-28 days. I have put fawns back on their mothers following the tranquilizing of the doe but only afte waiting 8 hours. Where did the 8 hours come from??? I just figured it was long enough, no real science here. The fawns did not show any ill effects, nor did the doe have any issues re-accepting the fawns.