  We investigate the properties of discrete breathers in a Bose-Einstein
condensate with two- and three-body interactions in optical lattice. In the
tight-binding approximation the Gross-Pitaevskii equation with periodic
potential for the condensate wavefunction is reduced to the cubic-quintic
discrete nonlinear Schr\"odinger equation. We analyze the regions of
modulational instabilities of nonlinear plane waves. This result is important
to obtain the conditions for generation of discrete solitons(breathers) in
optical lattice. Also using the Page approach, we derive the conditions for the
existence and stability for bright discrete breather solutions. It is shown
that the quintic nonlinearity brings qualitatively new conditions for stability
of strongly localized modes. The numerical simulations conform with the
analytical predictions.
