The effect of organically grown diets with contrasting carbohydrate composition on the establishment of Trichuris suis in pigs

Summary

Two diets with contrasting digestibility was formulated - the diet containing resistant carbohydrates (Diet 1) was based on triticale, barley, rapeseed cake and silage as the main ingredients while the diet with fermentable carbohydrates (Diet 2) was based on triticale, barley, blue lupines and chicory roots. Assuming that the pigs will consume approximately 7 % of the dry matter from silage and 15 % from chicory roots, the content of feed units for pigs (FEs) will be 0.96 and 1.09 FEs in Diets 1 and 2, respectively. After two weeks of adaptation, the pigs were infected with 2000 infective eggs of T. suis. Faecal egg samples were taken twice weekly to determine the number of parasite eggs excreted. All the pigs were slaughtered 12 weeks post infection (pi). The large intestine was divided into caecum and 5 colon sections. pH was measured in each section and samples were taken for chemical examinations. The remaining intestinal contents were collected to determine the worm burden. The weight gain on the pigs receiving Diet 1 was lower than on Diet 2 presumably reflecting a lower energy intake, primarily because of less consumption of the silage as expected but there was difference between infected and non-infected pigs. The two diets introduced significantly differences in the gastrointestinal environment with pH generally lower and the concentration of short-chain fatty acids (SCFA) generally higher when feeding diet 2 (130-150 mmol/kg digesta) compared to diet 1 (105-125 mmol/kg digesta) but with no significant differences between either pH or SCFA of infected and non-infected pigs. The former diet also clearly stimulated butyrate formation in the large intestine. The infected group receiving Diet 1 had higher faecal egg counts compared to the infected pigs receiving Diet 2 until 9 weeks pi, after which the two groups had similar mean egg counts until slaughter. However, the variation in faecal egg counts was substantial. No significant difference was found in the number of worms between the two groups.