The neutralino relic abundance is evaluated for a wide range of the
neutralino mass, 20GeV≤mχ≤1TeV, by taking into
account the full set of final states in the neutralino-neutralino annihilation.
The analysis is performed in the Minimal SuSy Standard Model; it is not
restricted by stringent GUT assumptions but only constrained by present
experimental bounds. We also discuss phenomenological aspects which are
employed in the companion paper (II. Direct Detection) where the chances for a
successful search for dark matter neutralino are investigated.Comment: (10 pages plain TeX, 8 figures not included, available from the
authors) DFTT-37/9