Kevin Bell

Nine flocks of sheep with "low worm egg count scouring" in the south west of Western Australia were investigated over a three-year period. There was no significant difference in the faecal worm egg counts of "scouring sheep" (diarrhoea and severe dag) compared to "normal sheep" (pelleted faeces and mild or no dag). Teladorsagia (Ostertagia) circumcincta and Trichostrongylus spp were the strongyles most commonly identified on total worm counts and differentiation of larvae recovered from faeces and pasture. Immature strongyle worms accounted for the largest proportion of total worm counts. Adult worm burdens were small in most sheep. Scouring sheep had significantly higher numbers of early fourth stage larvae. There was no histopathological evidence of bacterial or viral causes of scouring in any of the flocks that could be supported with bacteriology. Two flocks had marginal selenium status. One flock was diagnosed with helminthosis based on increased worm egg counts and high total worm counts. Larval hypersensitivity scouring, nutrition or a combination of these two factors were the most likely causes of scouring in the other eight mobs based on exclusion of other known causes of scouring. Treatment with moxidectin drench and an ivermectin controlled-release capsule did not change faecal moisture of treated sheep compared to untreated sheep three to five weeks after treatment.

Strongyle infections and diarrhoea are major problems for the sheep industry, but the nutritional factors determining faecal consistency and susceptibility to enteric diseases are not well understood. Soluble non-starch polysaccharides (sNSP) have been shown to affect the physico-chemical environment of the gut lumen, by increasing viscosity of digesta and affecting microbial fermentation in the large intestine; however, the role of sNSP in sheep has not been studied. sNSP have been shown to increase parasite establishment in the small intestine of mice (3) and decrease parasite establishment in the large intestine of pigs (2). Carboxymethylcellulose (CMC) is a non-fermentable viscous-forming agent that is used to study the effect of soluble NSP in increasing digesta viscosity independent of potential effects on fermentation (I). The aims of this study were to investigate whether increasing viscosity of digesta using CMC may affect establishment of Trichostrongylus colubriformis and Telodorsagio (Ostenagia) circumcincta in sheep and whether the type of roughage and CMC may affect faecal consistency in sheep with strongyle infections.

Although diarrhoea and faecal soiling of fleece are major problems for the sheep meat and wool industries, there is little information on the nutritional factors that determine faecal consistency in sheep. Research in monogastric species has shown that the soluble non-starch polysaccharide (sNSP) content of the diet is a major determinant of faecal consistency and susceptibility of animals to enteric diseases (2, 3), but there have been no studies on the role of sNSP in sheep. sNSP have profound effects on the physio-chemical conditions of the gut lumen by increasing viscosity of digesta and affecting microbial fermentation in the large intestine (2). Carboxymethylcellulose (CMC) is a non-fermentable viscous-forming agent that has been used in pig diets to study the effect of sNSP of increasing digesta viscosity, independently of potential effects on fermentation (2). This study aimed to investigate if CMC could be used as a model for studying the effect of increasing digesta viscosity in sheep and whether dietary CMC supplementation would have any detrimental effects on faecal consistency.