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Introduction: This study investigated the impact of zinc oxide (ZnO) on Campylobacter (C.) coli by in vivo and in vitro assays.
Methods and Results: By in vitro growth inhibition assays a high susceptibility of C. coli against ZnO could be observed . At concentrations ≥ 2.6 mM ZnO a decline in cell numbers occurred. Quantitative real-time-PCR assays demonstrated an upregulation of the main oxidative stress gene (katA) in response to ZnO treatment. The expression level of katA was increased by 5-fold after ZnO treatment. An experiment was carried out in pigs to elucidate the impact of ZnO as feed supplement on C. coli faecal excretion. Feeding a high-dosage ZnO concentration (3,100 mg kg-1) to piglets significantly reduced the faecal excretion of C. coli by up to 1 log CFU g-1 as compared to animals receiving a low (40 mg kg-1) or medium (100 mg kg-1) ZnO diet.
Conclusion : In vitro assays showed a high susceptibility of C. coli against ZnO. Adding high levels of ZnO to the diet of weaned piglets reduced C. coli excretion significantly. There is evidence for the induction of an oxidative stress response by ZnO supplementation in C. coli.
Summarized, supplementation of a high-dosage ZnO diet to piglets can reduce the C. coli load, potentially leading to a lower contamination risk of meat during slaughter.