Spotty Liver Disease (SLD) is a serious condition extensively affecting laying hens (particularly in free range systems), leading to losses through both bird mortality and reduced egg production. It is hypothesised that changes in the intestinal health/microbiota balance allow a multiplication of the causative organism Campylobacter hepaticus and the production of a toxin that causes the symptoms of the disease, including the liver lesions. The advantage of using feed additives include a reduction in the necessity to treat or to prevent SLD with antibiotics, a reduction in overall mortality during an outbreak and over the most common period of outbreaks (up to 35 weeks), and a trend towards reducing the negative production impact of SLD.