The use of sentinel birds to monitor coccidial infection in litter pens.

Two-week-old chickens susceptible to coccidiosis were introduced into litter pens for periods up to 48 hr in order to estimate the potential coccidial challenge. They were then transferred to cages and the infections acquired were estimated by oocyst output or by body weight gain and lesion scores. Moderate to severe infection occurred even when about 1,000 oocysts/gram were present in the litter. The results suggest that the brief introduction of "sentinel" birds into an infected environment may be a valuable method of assessing the actual coccidial challenge which groups of chickens acquire from exposure to litter. The technique may be used to monitor the effectiveness of anticoccidial drugs or the immune status of chickens kept in litter pens by comparing infections in "sentinels" and "in-pen" birds.