The primary objectives of this study were to determine if the common industry practices
of feeding undegradable intake protein and supplemental monensin may contribute to the
increased carriage and shedding of Campylobacter in feedlot cattle. Regardless of whether
rumen undegradable intake protein or ionophores contribute to Campylobacter carriage in cattle,
interventions designed to rid these pathogens before slaughter ultimately can help insure the
microbial safety of beef produced for human consumption. Thus, additional objectives of the
present study were to a) determine minimum inhibitory concentrations of two potential antiCampylobacter compounds, thymol and diphenyliodonium chloride (DIC), needed to achieve
efficacious reductions of C. jejuni in vitro and b) test the efficacy of these compounds at 1X and
3X their minimum efficacious dose in fed cattle.
Results from this study demonstrated that the anti-Campylobacter compounds exerted
significant bacteria-killing activity in the laboratory but revealed that extensive absorption and
degradation of the test compounds may indeed have occurred even with the rectal palpation
procedure, thus clearly indicating that additional research is needed to develop antiCampylobacter interventions for cattle. Results from our feeding studies demonstrate that the
common industry practices of feeding diets high in rumen undegradable intake protein or
supplemented with ionophores do not contribute to increased intestinal carriage or shedding of
Campylobacter spp. in fed cattle.