  The total photoproduction cross section at ultra-high energies is obtained
using a model based on QCD minijets and soft-gluon resummation and the ansatz
that infrared gluons limit the rise of total cross sections. This cross section
is introduced into the Monte Carlo system AIRES to simulate extended
air-showers initiated by cosmic ray photons. The impact of the new
photoproduction cross section on common shower observables, especially those
related to muon production, is compared with previous results.
