  Using a reformulated Kubo formula we calculate the zero-energy minimal
conductivity of bilayer graphene taking into account the small but finite
trigonal warping. We find that the conductivity is independent of the strength
of the trigonal warping and it is three times as large as that without trigonal
warping, and six times larger than that in single layer graphene. Although the
trigonal warping of the dispersion relation around the valleys in the Brillouin
zone is effective only for low energy excitations, our result shows that its
role cannot be neglected in the zero-energy minimal conductivity.
