  In the present paper we investigate the conservative conditions in Quadratic
Gravity. It is shown explicitly that the Bianchi identities lead to the
conservative condition of the left-hand-side of the (gravitational) field
equation. Therefore, the total energy-momentum tensor is conservative in the
bulk (like in General Relativity). However, in Quadratic Gravity it is possible
to have singular hupersurfaces separating the bulk regions with different
behavior of the matter energy-momentum tensor or different vacua. They require
special consideration. We derived the conservative conditions on such singular
hypersurfaces and demonstrated the very possibility of the matter creation. In
the remaining part of the paper we considered some applications illustrating
the obtained results.

General Relativity and Quantum Cosmology;High Energy Physics - Theory