The effect of dietary carbohydrates and Trichuris suis infection on pig large intestine tissue structure, epithelial cell proliferation and mucin characteristics

Two experiments (Exps. 1 and 2) were performed to study the influence of Trichuris suis infection and type of dietary carbohydrates on large intestine morphology, epithelial cell proliferation and mucin characteristics. Two experimental diets based on barley flour were used; Diet 1 was supplemented with resistant carbohydrates from oat hull meal, while Diet 2 was supplemented with fermentable carbohydrates from sugar beet fibre and inulin. In Experiment 1, 32 pigs were allocated randomly into four groups. Two groups were fed Diet 1 and two groups Diet 2. Pigs from one of each diet group were inoculated with a single dose of 2000 infective T. suis eggs and the other two groups remained uninfected controls. In Experiment 2, 12 pigs were allocated randomly into two groups and fed Diet 1 or Diet 2, respectively, and inoculated with a single dose of 2000 infective T. suis eggs. All the pigs were slaughtered 8 weeks post inoculation (p.i.). The worm counts were lower in pigs fed Diet 2 in both experiments, but not significantly so. Both diet and infection status significantly influenced the tissue weight of the large intestine. In both experiments, pigs fed Diet 2 had heavier large intestines than pigs fed Diet 1 and in Experiment1 the infected pigs of both diets had heavier large intestines than their respective control groups. Diet and infection also significantly affected the morphological architecture and mucin production in both experiments. Pigs fed Diet 1 had larger crypts both in terms of area and height than pigs fed Diet 2 and T. suis infected pigs on both diets in Experiment 1 had larger crypts than their respective control groups. The area of the mucin granules in the crypts constituted 22-53% of the total crypt area and was greatest in the T. suis infected pigs fed Diet 1. Epithelial cell proliferation was affected neither by diet nor infection in any of the experiments. The study showed that both T. suis infection and dietary carbohydrates significantly influence the morphological architecture and the production and composition of mucins in the large intestine of pigs and suggests that both factors are important in large intestine function and that carbohydrates may play a role in the susceptibility to intestinal helminth infections.