  In a region $R$ consisting of unit squares, a (domino) tiling is a collection
of dominoes (the union of two adjacent squares) which pave fully the region.
The flip graph of $R$ is defined on the set of all tilings of $R$ where two
tilings are adjacent if we change one from the other by a flip (a $90^{\circ}$
rotation of a pair of side-by-side dominoes). Let $n\geq 1$ and $m\geq 2$ be
integers. In a recent paper it was proved that the flip graph of $(2n+1)\times
2m$ quadriculated torus consists of two isomorphic components. In this paper,
we generalize the result to the toroidal grid $T(2n+1,2m,2r)$ which is obtained
from an $(2n+1)\times 2m$ chessboard by sticking the left and right sides and
then identifying the top and bottom sides with a torsion $2r$ squares for
$1\leq r\leq m$. For a tiling $t$, we associate an integer called forcing
number as the minimum number of dominoes in $t$ that is contained in no other
tiling. As an application, we obtain that the forcing numbers of all tilings of
$T(2n+1,2m,2r)$ form an integer-interval. Moreover, we prove that the maximum
value of the interval is $\frac{m(2n+1)}{2}$ if $\frac{m}{(r,m)}$ is even, and
$\frac{m(2n+1)+(r,m)}{2}$ otherwise.
