Salmonella can be introduced into the herd through infected
purchased pigs (Fedorka-Cray et al., 1997) thereby increasing Salmonella
prevalence at slaughter (van der Heijden et al., 2005). Davies
et al. (2000) demonstrated that gilts showed increased
Salmonella excretion after introduction to a new herd, and purchasing
replacement stock from more than three supplier herds and
finishers from more than one, increased the odds of test seropositivity
(Lo Fo Wong et al., 2004; Quessy et al., 2005). Ideally producers
should be aware of the Salmonella status of their suppliers and
stock should be sourced from a Salmonella-free unit.