Theoretical expressions are obtained for the spin-wave spectrum in a ferromagnetic cubic crystal with variable-valence ions. Interactions up to the fourth coordination shell (i.e., with 32 neighbors) are taken into account. Both a Heisenberg-type superexchange and a non-Heisenberg double exchange are assumed to occur in the system. The anisotropy energy has a single-ion character. Eighteen interaction parameters are taken into account. The formulas derived for the spin-wave energy are valid for the first full Brillouin zone. For three principal crystallographic directions, the calculated dispersion curves are compared with the experimental curves obtained for La0.83Ca0.17MnO3 using inelastic neutron scattering. As a result, the numerical values of the total exchange parameters for each of the four coordination shells can be found.