  We study the rotational evolution of a protoneutron star with hyperons and
nucleons or solely nucleons in its core due to the escape of the trapped
neutrinos. It is found that at the early stage of its evolution, the stellar
crust contracts significantly, consequently the star spins up. At the late
stage, a the protoneutron star with hyperons, it keeps shrinking and spinning
up till all the trapped neutrinos escape. Consequently, the distribution of the
stellar initial spin periods is skewed toward shorter periods. For a
protoneutron star with only nucleons, the expansion of its core dominates, and
the stellar rotation slows down. After the neutrinos escape, the range of the
spin periods is narrower than the initial one, but the distribution is still
nearly uniform. If the hyperonic star is metastable, its rotational frequency
accelerates distinguishedly before it collapses to a black hole.
