“…The rumen enzyme is probably similar to jackbean urease in its Ni content, jUdging by the stimulation of rumen urease activity by dietary Ni (Spears et aI., 1977;Spears and Hatfield, 1978). No urease activity was found in either starved, antibiotic-treated ciliate protozoa (Onodera et al, 1977) or in Piromyces or Neocallimastix fungal isolates . No urease activity was found in either starved, antibiotic-treated ciliate protozoa (Onodera et al, 1977) or in Piromyces or Neocallimastix fungal isolates .…”