Coccidial infection with Eimeria tenella and caecal defaecation in chicks.

1. The periodicity of caecal defaecation was investigated in chicks infected with Eimeria tenella. The birds were illuminated for 12 h/d (07.00-19.00) and faeces were collected at 3-h intervals for up to 21 d. 2. In uninfected birds caecal faeces were never collected during the dark period. During the periods 07.00-10.00 h, 10.00-13.00 h, 13.00-16.00 h and 16.00-19.00 h, caecal defaecation occurred on approximately 44, 19, 55 and 91% of the total number of days respectively. 3. In infected birds production of haemorrhagic caecal faeces began from between 90 and 156 h after infection and continued during both light and dark periods for between 12 and 48 h. After this period, no caecal faeces were observed for between 39 and 120 h. Normal caecal defaecation resumed from between 198 and 264 h.