Reducing ileitis in summer P

orcine proliferative enteropathy (PPE), often known as ileitis, is an im- portant production intestinal disease with a huge economic impact. PPE is highly prevalent (90%) and is caused by the gram-negative intra- cellular bacterium Lawsonia intracellularis. The exact mechanisms of

spread are not known. Studies suggest that infected faeces are the major vehicle for movement of the organism around the farm. In practice it is well accepted that during summer, especially on days when there is a big difference in temperature between day and night, outbreaks of ileitis in heavy pigs can occur. The mechanism underlying this phenomenon is not totally clear, but it can be speculated that it is linked to overeating. When pigs are exposed to high temperatures, they will reduce feed intake; when the temperature drops at night or the next day, they will overeat to compensate. When pigs overeat, the retention time of the digesta in the stomach is short- ened, resulting in more substrate arriving at the end of the ileum and entering the large intestine. This excess of substrate might be used for L. intracellularis to over-proliferate and cause an outbreak. Therefore, it could be hypothesised that the proliferation of L. intracellularis could be prevented by limiting the amount of substrate arriving at the end of the ileum and entering the large intestine. Taking this into consideration the following feeding strategies could be advised: • Reduce the amount of fermentable carbohydrates in the diets. Fermenta- ble carbohydrates are a substrate that the bacteria can easily use to prolifer- ate. Therefore, reducing the amount of fermentable carbohydrates in the diet during summer will help to reduce heat stress and avoid the proliferation of bacteria.

• Increase the level of inert fibre in the diets. Inert fibre will help to in- crease the transit time in the small and large intestine and will not increase the proliferation of bacteria.

• Formulate low crude protein (CP) diets: reducing the CP in the diet will prevent CP fermentation in the large intestine, reducing heat stress and the production of toxic amines that also affect gut integrity.

• Increase the feed structure: Fine pellet diets will have a shorter reten- tion in the stomach, and the passage of nutrients to the small intestine will be too fast resulting in too much non-digested substrate arriving at the end of the ileum. Increasing the feed structure by adding coarse particles in the diet might increase the retention time of the digesta in the stomach resulting in a more gradual transition of nutrients to the small intestine. Nutritionists should aim to have 15% of the particles bigger than 1.4 mm in the diet in order to prolong the retention time in the stomach. Ideally, nutritionists should create this feed structure with fibre by-products with a low energy value such as wheat straw or sunflower hulls. In practice, if those feedstuffs are not easily available, then the feed structure could be created by adding coarse-rolled barley into the diet.

Francesc Molist

holds a PhD in animal nutrition from the Universitat Autònoma de Barcelona in Spain. He has been working for Schothorst Feed Research in the Neth- erlands since 2011, most recently as manager re- search & development.


▶ PIG PROGRESS | Volume 37, No. 7, 2021

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