“…This effect can be used to sequentially reduce the level of excretion and environmental challenge in consecutive flocks to the point when total elimination is more likely (Mead, 2000). Wider studies are needed to fully define this and further developments are in progress (Andreatti et al, 2003). To be maximally effective competitive exclusion should be administered shortly before a potential exposure to Salmonella spp., so administration by spray at the hatchery is generally superior to water administration on farm (Mead, 2000;Patterson and Burkholder, 2003).…”