We have discussed the effect of the split of the energy levels between spin-up and spin-down electrons caused by magnetization on the magnon-induced resistivity in ferromagnetic metals at low temperatures. As a result of such an energy split, the low-temperature magnetic resistivity always declines exponentially with decreasing temperature in the single-hand model, while it may probably be enhanced in certain conditions in the two-band model. The comparison between the low-temperature expression of magnetic resistivity deduced from the single-band model considering the energy-gap in the spin-wave spectrum and the experimental data of Tb and Dy shows agreement not only on temperature dependence of resistivity at low temperatures but on the magnitude of high-temperature magnetic resistivity as well.