The Effect of Fermentable Carbohydrates on Experimental Swine Dysentery and Whip worm Infections in Pigs

Summary

Two diets with contrasting fermentability were formulated. Diet 1 containing resistant carbohydrates was based on triticale, barley, rapeseed cake as the main ingredients supplemented with grass clover silage. Diet 2 containing fermentable carbohydrates was based on triticale, barley, blue lupines and dried grinded chicory roots. The two diets were fed to seventy-two pigs tested negative for T. suis and swine dysentery were divided into 8 groups (A-H) according to weight and sex as follows:
Group A: Diet 1, T. suis and B. hyodysenteriae; Group B: Diet 2, T. suis and B. hyodysenteriae, Group C: Diet 1, B. hyodysenteriae; Group D: Diet 2, B. hyodysenteriae, Group E: Diet 1, T. suis; Group F: Diet 2, T. suis; Group G: Diet 1, control, and Group H: Diet 2, control. The pigs were fed according to weight once a day. After two weeks of diet adaptation, pigs in group A, B, E, and F inoculated with 2000 infective T. suis eggs each and pigs in group A, B, C, and D were challenged with 1 x 109 colony-forming units of B. hyodysenteriae each on three consecutive days. Group G and H were uninfected control groups. The pigs were weighed every other week and monitored daily for clinical symptoms. Faecal samples were collected twice a week to monitor the cause of dysentery. The faecal samples were cultured selectively for the presence of B. hyodysenteriae as well as scored according to consistency (normal, loose, watery/mucoid, and bloody diarrhoea), which was utilized as a measure of clinical disease. All pigs were slaughtered 6 weeks post infection (p.i.) over a course of 5 days. At slaughter a faecal sample was collected for examination of T. suis eggs and a macroscopic pathological examination was performed on each pig. Tissue samples were taken from the anterior part of the colon for histopathological examinations. The large intestine was divided into caecum and 5 colon sections. The sections were emptied and weighed and pH was measured in the contents of each section. Samples were taken from the contents for chemical analyses. The remaining contents were used for recovery of T. suis. T. suis were not found at slaughter and no B. hyodysenteriae were isolated from any of the control pigs in group G and H. No clinical signs of dysentery were found in pigs experimentally challenged with B. hyodysenteriae that were receiving Diet 2 (Group B and D). Likewise, no bacteria were isolated from faeces in any of these pigs. In contrast, clinical symptoms of dysentery were observed in all experimentally B. hyodysenteriae pigs fed Diet 1 (Group A and C, except 1 pig in Group A) and similarly the bacteria were found in faeces of all these pigs at different times during the experiment starting from 6 days p.c. There was no difference in worm counts between any of the T. suis infected groups (Group A, B, E, and F). The lowest worm burdens, however, were found in the pigs fed Diet 2 (Group B and F). The frequency of swine dysentery was lower in pigs with dual infections, but consistent throughout the course of the study. Pigs only infected with B. hyodysenteriae, on the other hand, had higher frequency of clinical symptoms, but only over a period of 2 weeks from 9 days to 23 days p.c. The weight gain did not differ significantly between the groups, but was lowest in pigs with clinical swine dysentery (Group A and C). Diet 2 prevented completely the occurrence of swine dysentery in both experimentally infected groups (A and C) presumably because of rapid fermentation of non-digestible carbohydrates constituents; galactans from lupins and fructans from chicory.