Intestinal digesta viscosity decreases during coccidial infection in broilers

1. The effect of intestinal digesta viscosity on bird performance in chicke ns with coccidiosis was compared to those without coccidiosis. 2. Six hundred chicks were divided into five groups: one control group was fed a basal maize/soyabean-based diet and the other groups were fed the bas al diet supplemented with 2, 4 6 or 8 g carboxymethyl cellulose (CMC) per k g of feed. At 14 d of age half the birds were individually inoculated with sporulated oocysts of Eimeria acervulina and Eimeria praecox: 3. Intestinal digesta viscosity increased with increasing inclusion of CMC. This effect was considerably less pronounced in inoculated than in non-ino culated birds. 4. There was a significant negative effect on live weight gain and feed con version ratio (FCR) with increasing CMC inclusion in non-inoculated birds, but in inoculated birds there was no clear relation between CMC inclusion a nd performance. Neither intestinal lesion scores, nor numbers of Clostridiu m perfringens in the caeca, were significantly affected by CMC: inclusion. 5. Across all diets inoculation impaired growth rate by 9% and FCR by 8%, b ut did not affect the amount of C. perfringens in the caeca.