frontline is the way to go, put it in a serenge squeese a bubble of it out to the tip and place it about one inch from the vent not to mutch, No fertility issues, i think someone may have put an entire tube on a chicken and had a problem, but you really cant go wrong. I believe in it, if bill is using it after all his hatching issues i would think that would make believers out of most. It is safe and does the job!!
good luck happy new years all!!
good luck happy new years all!!