  Isaak posed the following problem. Suppose $T$ is a tournament having a
minimum feedback arc set which induces an acyclic digraph with a hamiltonian
path. Is it true that the maximum number of arc-disjoint cycles in $T$ equals
the cardinality of minimum feedback arc set of $T$? We prove that the answer to
the problem is in the negative. Further, we study the number of arc-disjoint
cycles through a vertex $v$ of the minimum out-degree in an oriented graph $D$.
We prove that if $v$ is adjacent to all other vertices, then $v$ belongs to
$\delta^+(D)$ arc-disjoint cycles.
