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Abstract 1. The effect of intestinal digesta viscosity on bird performance in chickens 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 basal diet supplemented with 2, 4, 6 or 8 g carboxymethyl cellulose (CMC) per kg 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-inoculated birds.
4. There was a significant negative effect on live weight gain and feed conversion ratio (FCR) with increasing CMC inclusion in non-inoculated birds, but in inoculated birds there was no clear relation between CMC inclusion and performance. Neither intestinal lesion scores, nor numbers of Clostridium perfringens in the caeca, were significantly affected by CMC inclusion.
5. Across all diets inoculation impaired growth rate by 9% and FCR by 8%, but did not affect the amount of C. perfringens in the caeca.
INTRODUCTION
High viscosity of the intestinal contents has been shown to cause digestive and health problems in modern broilers. The viscosity is caused by watersoluble non starch polysaccharides (NSP) mainly from cereals (barley, oats and wheat), which decrease digesta passage rate and availability of nutrients (Hesselman and Aman, 1986; van der Klis et aL, 1993b). The problem can to a great extent be overcome by addition of enzyme preparations which digest the NSP into smaller polymers, thus decreasing the digesta viscosity (Bedford and Morgan, 1996). It has been suggested that increased digesta retention time facilitates bacterial colonisation of the proximal small intestine (Vahjen et aL, 1998). Data from Elwinger and Tegl6f (1991) and jansson et al. (1990) also indicate that addition of enzymes may reduce the frequency of necrotic enteritis in broiler chickens. Necrotic enteritis is an important chicken disease throughout the world and Clostridium perfringens type A has been demonstrated as the causal agent (Ficken, 1991). This species is normally part of the bacterial flora of the gastrointestinal tract of poultry but, under certain conditions, which are not completely understood, they may multiply and cause...