Coccidiosis in broilers: evaluation of infection by the examination of broiler house litter for oocysts.

A study was made of the incidence of coccidial oocysts in approximately 1,660 samples of litter from 48 broiler houses on 5 broiler farms during a 12 month period during 1974-75. Oocysts of Eimeria acervulina and Eimeria maxima predominated in the samples but oocysts resembling Eimeria brunetti and Eimeria tenella were sometimes present. Oocyst numbers were extremely low and variable at 2 weeks, probably because of the small proportion of faecal material present at this time, reached a peak at 4-6 weeks and dropped to a low level at 8-9 weeks. For the last 3 crops of birds reared in these houses, the anticoccidial drug Monensin was used and extremely small numbers of oocysts were found in the litter. Significantly improved food conversion ratios and body weights were noted in these broilers. The results indicate that the examination of a few litter samples for oocysts, provided that they are taken from broiler houses at regular intervals after the 3rd week, could provide useful information on the effectiveness of anticoccidial drugs in controlling coccidiosis.