Assessing the Efficacy of Oregano, Apple Cider Vinegar, and Citric Acid in Water as a Treatment for Spotty Liver Disease Caused by Campylobacter hepaticus in Challenged SPF Laying Hens

Spotty liver disease (SLD) caused by <i>Campylobacter hepaticus</i> has emerged as an important cause of disease in table egg layers in the United States. The disease associated with <i>C. hepaticus</i> results in focal lesions on the livers of infected birds, reduced egg production, and increased mortality of layer hens. Currently, there are no approved treatments and no commercial vaccine available for <i>C. hepaticus</i>, and very limited research is available supporting best approaches for the control of <i>C. hepaticus</i> in organic or antibiotic free-laying hens. We assessed the potential effects of water acidification treatments for the control of <i>C. hepaticus</i> in challenged specific-pathogen-free (SPF) chickens and transmission of the organism to naïve birds. The objective of this study was to develop a challenge and treatment model to assess the effects of oregano, apple cider vinegar, and citric acid as potential control measures for <i>C. hepaticus</i> in challenged birds. We divided 148 SPF chickens, 17 wk of age, into five groups; four groups (with 51% of the birds in each group orally challenged with <i>C. hepaticus</i>) and one negative control group (<i>n</i> = 8). A dose of 10⁷ cfu/ml of <i>C. hepaticus</i> was given on day 1, day 4, and day 7 by oral gavage. At day 10 after the day 1 challenge, three challenged groups were treated for 5 days with either oregano, apple cider vinegar, or citric acid in the water. One challenged but not treated group and the negative control received only water as treatment. Bile and liver samples from challenged and nonchallenged naïve exposed birds were collected from euthanatized birds at days 9, 15, 20, and 27 after the first day challenge to evaluate the presence of <i>C. hepaticus</i> gross lesions and detection via culture and polymerase chain reaction (PCR) confirmation. Results showed that challenged birds were able to develop mild to moderate multifocal liver lesions resembling SLD. Severe lesions were evident in the naïve, exposed nonchallenged birds. Positive bacterial culture and colony PCR positives were found in challenged birds in each challenge group. Results from PCR of DNA extracted from liver samples were able to detect a greater number of <i>C. hepaticus</i>-positive samples than culture PCR of bile alone. Treatment with oregano, apple cider vinegar, or citric acid was not able to clear <i>C. hepaticus</i> from challenged birds because more than 44% of the challenged birds remained positive on liver PCR analysis posttreatment. Results also found that <i>C. hepaticus</i> could be passed horizontally because more than 29% of the naïve nonchallenged birds became <i>C. hepaticus</i> positive postintroduction to challenged birds. Overall, this study found that this challenge model for <i>C. hepaticus</i> was successful and that treatments did not clear <i>C. hepaticus</i> in challenged birds. Nevertheless, it appears that acidifying the water could help to reduce <i>C. hepaticus</i> load in naïve birds because in groups treated with oregano, apple cider vinegar, or citric acid <i>C. hepaticus</i> could not be cultured from bile.