Extracts of sweet chestnut (Castanea sativa Mill.) which contain hydrolysable tannins are used to prevent diarrhoea in farm animals due to the astringent effect of tannins. The aim of this study was to establish whether long-term treatment with the chestnut extract as a feed additive affects the acetylcholine (ACh)-triggered contractions of isolated rat ileum. Wistar rats of both sexes were divided into 4 male and 4 female groups with 6 animals in each group. The first, second and third groups

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... f both sexes received feed with 3, 15 and 30 g of chestnut extract per kg, respectively. The fourth group of both sexes received feed without the added chestnut extract and served as the control group. After the 90-day trial, the animals were euthanized, and ilea were isolated and placed in an organ bath filled with Tyrode's solution. Ilea were connected to an isometric transducer. Ileal contractions were triggered by 0.005, 0.01, 0.05, 0.1, 0.5, 1.0, 5.0 and 10.0 mg of ACh, and contractions were recorded. The groups exhibited dose responsiveness to the ACh treatment steps; however, no significant differences in the contraction intensity were observed among the groups at the same ACh dose level. These results suggest that long-term treatment with chestnut extract as an astringent does not influence the intensity of ileal contractions triggered by ACh. Thus, no adverse effect on intestinal motility can be expected during a long-term use of chestnut extract as a feed additive in livestock production; however, further studies in target animal species are needed to confirm the findings.