Ovine Johne’s Disease (OJD) is a chronic debilitating enteric disease in sheep caused by the bacteria Mycobacterium avium subsp. paratuberculosis (MAP). In the past, this disease has had major economic and production impacts due to extremely high mortality rates, poor growth and poor wool quantity and quality. Currently OJD is controlled with the Gudair® vaccine, which despite being highly effective in reducing mortalities, does not prevent infection, with clinically and sub-clinically affected sheep still seen on some properties. The aim of this study was to investigate husbandry and biosecurity factors that may influence the effectiveness of Gudair® vaccine on properties vaccinating for a minimum of five years. The study targeted OJD infected flocks in NSW, which had met a number of selection criteria. A five-page questionnaire investigating a range of biosecurity and husbandry practices was developed and producers were interviewed face-to-face. Faecal samples from 350 sheep from each property were collected and pooled into 14 groups. Using pooled faecal culture and IS900 quantitative PCR, samples were analysed for the presence of viable MAP. This study yielded results from a total of 30 farms with a wide range of findings. There were some practices which were seen to be present on all properties and others which only were only present in a portion of properties. Due to time limitations, disease prevalence results were not available for this manuscript. Further research is needed to correlate the findings of this study with the OJD prevalence on sampled farms.
Keywords:
biosecurity, Gudair®, husbandry, ovine Johne’s disease, sheep, vaccine effectiveness