Why is bacterial conjugation so rare?

[kem]

I have recently conducted a biology experiment that requires me to calculate percent conjugation. The value that I obtained is very low. Why is bacterial conjugation so rare?

[Esrevinu]

It is believed that the F plasmid carries the genes responsible for conjugation/formation of the pilus, however it won't conjugate with bacteria that already have the F plasmid. One must be a donor, and one must be a receiver. The donor has the F plasmid, while the receiver does not. If a large portion of your bacteria already have the F-plasmid, there will not be a large percent of conjugation. More information about what you did (experimental set up, strains used, plasmids, etc) would be useful. Were you looking for Hfr? Regular F+? Etc...

Edited April 30, 2013 by Esrevinu

[CharonY]

Rare relative to what?