  We examine and compare the behaviour of the scalar field slice energy in
different classes of theories of gravity, in particular higher-order and
scalar-tensor theories. We find a universal formula for the energy and compare
the resulting conservation laws with those known in general relativity. This
leads to a comparison between the inflaton, the dilaton and other forms of
scalar fields present in these generalized theories. It also shows that all
such conformally-related, generalized theories of gravitation allow for the
energy on a slice to be invariably defined and its fundamental properties be
insensitive to conformal transformations.
