Herbal extracts and preparations are a constantly growing group of feed additives. The introduction of essential oils (EOs) to animal diet represents one of the strategies aimed at replacing the use of antibiotics as growth promoters for pig production. EOs, including clove oil, have been used in pig breeding with the main focus on digestive system functions. The beneficial effect of clove oil on swine production performance results from its antioxidant activity, the ability to modulate intestinal microbiota and increasing feed digestibility. The occurrence of gastrointestinal signs like diarrhea requires causative and symptomatic treatment in animals. The symptomatic therapy should include the regulation of gut motility disorders. Therefore, the aim of the study was to evaluate the effect of clove oil and its active ingredients on swine jejunal smooth muscle.
The study was conducted on jejunal segments collected from adult pigs which underwent routine slaughter procedure. Intestinal preparations were examined under isometric conditions. The effect of clove essential oil and four of its active ingredients (eugenol, thymol, carvacrol, cinnamaldehyde) were analyzed.
The results showed that clove oil, eugenol, carvacrol, thymol and cinnamaldehyde induce a dose-dependent modification of the spontaneous contractility of swine jejunum. The most advanced myorelaxant effect was generated by intact clove oil used in a dose of 10 µL/mL. The reaction exceeded the magnitude of the relaxation induced by the reference relaxant agent. Among the individual components, eugenol and thymol turned out to be the most potent antispasmodic agents, followed by carvacrol. Cinnamaldehyde produced an opposed contractile effect of a mild intensity.
In conclusion, the obtained data suggest that clove oil extract and eugenol are responsible for the main effect on jejunum contractility. The antispasmodic effect desired in diarrheic animals can be expected only if clove oil is used as feed additive in relatively high doses.