  We derive an integro-differential equation for propagation of cosmological
gravitation waves in spatially closed cosmology whereas the traceless
transverse tensor part of the anisotropic stress tensor is free streaming
neutrinos (including antineutrinos), which have been traveling essentially
without collision since temperature dropped below about $ 10^{10} K$. We
studied the short wavelengths and long wavelengths of gravitational waves (GWs)
that enter the horizon in closed spacetime. The solution shows that the
anisotropic stress reduces the squared amplitude by 76% for wavelengths that
enter the horizon during radiation-dominated phase and this reduction is less
for the wavelength that enter the horizon at later times. At the end we compare
the results to the
