Thymol in Different Parts of the Rabbit Intestinal Tract: Its Effect on Intestinal Microbiota, Morphometry and Immunoglobulin A

The positive effect of thymol on gut health largely depends on its absorption from the intestinal tract and its biotransformation processes in the intestinal wall. A total of 32 rabbits were randomly divided at 35 days of age into a control (CG) and an experimental group (EG) that received thymol at 250 mg/kg feed. Thymol concentration was significantly higher in the caecum than in the ileum (p < 0.05), which is likely associated with caecotrophy and reduced enzymatic activity in the distal segments of the small intestine. Coliform bacteria (p = 0.0095) and lactic acid bacteria (LAB; p = 0.0002), Staphylococcus spp. (p = 0.0002), and Enterococcus spp. (p = 0.0002) in the duodenum; LAB (p = 0.0003) and Enterococcus spp. (p = 0.0002) in the ileum; and other Enterobacteriaceae (p = 0.0002) and LAB (p = 0.0068) in the caecum were significantly higher in the EG. Despite the significantly lower thymol concentration in the ileum compared to the caecum, the beneficial LAB was positively affected. A decrease in immunoglobulin A in all parts of the intestinal tract except the colon was a result of the modulation of mucosal immunity. Thymol at this concentration modulated the gut ecosystem without disrupting its beneficial components, thereby helping maintain intestinal homeostasis.