Study of the biological and economic impact of OJD in affected sheep flocks in NSW : 12 farm mortality study.

Abstract

This study provides industry with factual information about the impact of OJD on farms in southern Australia. This is needed to assess the magnitude of the OJD problem and to direct control and management programs. On 12 farms, the average annual OJD mortality rate based on inventory records from 2002-2004 was 6.8% (range 1.8% to 17.5%), well above the accepted annual mortality rate (from all causes) for Australian sheep flocks. OJD losses accounted on average for 70% (range 17% to 100%) of the estimated total financial loss associated with sheep deaths in 2002. In addition this project confirmed that prevalence based on pooled faecal culture (PFC) could be used as an indicator of OJD mortality level and provided support for further investigation of several risk factors in a larger future study (MLA OJD.038). The gross margin model developed provides estimates of on-farm cost of OJD and of vaccination control for wool and sheep-meat enterprises including break-even points for vaccination at various prevalence levels. We recommend that producers, through industry extension activities, be informed of the substantial losses associated with OJD and be encouraged to apply the model to support decision making regarding OJD control.