  The decoupling of a cold relic, during a decaying-particle-dominated
cosmological evolution is analyzed, the relic density is calculated both
numerically and semi-analytically and the results are compared with each other.
Using plausible values (from the point of view of supersymmetric models) for
the mass and the thermal averaged cross section times the velocity of the cold
relic, we investigate scenaria of equilibrium or non-equilibrium production. In
both cases, acceptable results for the dark matter abundance can be obtained,
by constraining the reheat temperature of the decaying particle, its mass and
the averaged number of the produced cold relic. The required reheat temperature
is in any case lower than about $20 {\rm GeV}$.
