Aims: This study investigated the impact of zinc oxide (ZnO) on Campylobacter coli by in vivo and in vitro assays.
Methods and results: By in vitro growth inhibition assays, a high susceptibility of Camp. coli against ZnO could be observed. At concentrations ≥ 2.6 mmol l(-1) ZnO, a decline in cell numbers occurred. Quantitative real-time PCR assays demonstrated an up-regulation of the main oxidative stress gene (katA) in response to ZnO treatment. The expression level of katA was increased by fivefold after ZnO treatment. An experiment was carried out in pigs to elucidate the impact of ZnO as feed supplement on Camp. coli faecal excretion. Feeding a high-dosage ZnO concentration (3100 mg kg(-1) ) to piglets significantly reduced the faecal excretion of Camp. 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 Camp. coli against ZnO. Adding high levels of ZnO to the diet of weaned piglets reduced Camp. coli excretion significantly. There is evidence for the induction of an oxidative stress response by ZnO supplementation in Camp. coli.
Significance and impact of the study: Supplementation of a high-dosage ZnO diet to piglets can reduce the Camp. coli load, potentially leading to a lower contamination risk of meat during slaughter.
Keywords: Campylobacter coli; excretion; feed supplementation; pigs; zinc oxide.
© 2013 The Society for Applied Microbiology.