Epidemiological studies of coccidiosis in the domesticated fowl (Gallus gallus):III. The influence of the fowl's defaecation pattern on the excretion patterns of Eimeria tenella and E acervulina oocysts.

Fifteen 61-day-old chickens (3 lots of 5) caged singly were inoculated five times during 3 days with Eimeria tenella or E. acervulina to simulate field infections, or kept as uninfected controls. During a 32 h experimental period of constant illumination, beginning on the tenth day after the first inoculation, every dropping produced by the birds as recorded, collected separately and examines for oocysts. All the chickens exhibited a bimodal pattern of colonic defaecation between 07.30 and 15.30 GMT the next day, with peaks at 17.00 on the first day and 11.00 on the second. Caecal defaecation practically ceased between 17.30 and 02.30 the next morning. Overall, colonic and caecal droppings were passed in the ratio 11.1:1. The patterns of oocyst excretion of both Eimeria species during the same 32-hour period exhibited peaks at 15.30 on the first day. Oocysts of either species were found both in caecal and colonic droppings. The chickens' defaecation pattern was superimposed upon the parasites' oocyst excretion patterns, the influence being more marked when lower numbers of oocysts were being excreted.