Metagalactic protons of ultra-high energies

The flux density of ultra-high-energy metagalactic protons generated by normal galaxies is calculated. Energetic losses of protons at interaction with the 2.7° relict and infrared radiations are revised. The time change of the energy of protons with different energies is estimated. The influence of fluctuations of energetic losses of protons on their spectrum is evaluated. The measured spectrum of cosmic rays can have a steepening (Δγ≈1.6) atE～3×10¹⁹eV instead of a sharp break expected previously.