The efficacy of feed additives to reduce the impact of Spotty Liver Disease
Spotty Liver Disease (SLD) is a bacterial illness in laying hens that often results in reduced egg production and increased mortality. Proactive prevention or minimisation of the severity of SLD takes priority over antibiotic treatment of the disease after the outbreak has already been identified, to reduce any associated mortality and productivity losses. To date, there has been little tangible evidence produced on non-antibiotic preventative treatments for SLD in laying hens, although anecdotally, the inclusion of feed additives, such as prebiotics, organic acids and/or other plant-based extracts, has reduced the severity of the disease under on-farm conditions. This project found that none of the feed additives were able to significantly reduce the occurrence of SLD under controlled, laboratory conditions. However, under on-farm conditions, some effect equivalent to antibiotic treatment was demonstrated using oregano and sanguinarine based products. These included reductions in the necessity to treat with antibiotics, overall mortality during the disease outbreak and impact on production. The results of this study suggest that more work is required to better understand SLD and the benefits that some feed additives may have in reducing the impact of disease.