  This paper examines the possibility that hadronic processes produce the >100
MeV photons in the prompt phase of gamma-ray bursts (GRBs) observed by the
Fermi-LAT. We calculate analytically the radiation from protons and from
secondary electron-positron pairs produced by high energy protons interacting
with gamma-rays inside of the GRB jet. We consider both photo-pion and
Bethe-Heitler pair production processes to create secondary electrons and
positrons that then radiate via inverse Compton and synchrotron processes. We
also consider synchrotron radiation from the protons themselves. We calculate
the necessary energy in protons to produce typical Fermi-LAT fluxes of a few
microJy at 100 MeV. For both of the photo-pion and Bethe-Heitler processes, we
find that the required energy in protons is larger than the observed gamma-ray
energy by a factor of a thousand or more. For proton synchrotron, the protons
have a minimum Lorentz factor ~2x10^6. This is much larger than expected if the
protons are accelerated by relativistic collisionless shocks in GRBs. We also
provide estimates of neutrino fluxes expected from photo-hadronic processes.
Although the flux from a single burst is below IceCube detection limits, it may
be possible to rule out photo-hadronic models by adding up the contribution of
several bursts. Therefore, photo-hadronic processes seem an unlikely candidate
for producing the Fermi-LAT radiation during the prompt phase of GRBs.
