I think 24 hours is the extreme. If you cut-off their feed at 12 hours prior, they will have empty crops, which makes pulling it thru the cavity much easier, but they will still have a fair amount of "stuff" in their digestive track. I have found that after 18 hours w/ no feed, most of the digestive track is cleared. If your good at processing, 12 hours is sufficient, but you need to be very careful you don't puncture the intestines. Make sure they still have access to water until close to the end.