OREGANO DIET SUPPLEMENTATION ENHANCES SWINE GUT DEFENCE ABILITY

Different studies have focused on use of natural compounds as alternative to synthetic additives to avoid the growing problem of antibiotic resistance. Among officinal plants Origanum vulgare L. has been shown to possess interesting antioxidant and antibacterial properties [1]. In addition, oregano is able to induce a higher glycoconjugate production in gut creating a physical barrier against microorganisms [2]. This study aimed to evaluate the effects of oregano aqueous extract (OAE) dietary supplementation on pig intestine complex carbohydrates, detected by conventional histochemistry, and oxidative stress, using as target molecule Bcl-2 Associate X protein (BAX). 32 pigs were divided in two groups and fed according to the following dietary treatments: (1) degermed corn-barley-soybean-based diet (CTR group); (2) CTR group diet supplemented (2 g/kg) with OAE (O group) (OPBA Approval E81AC.10/A). Glycohistochemical and immunohistochemical analyses were carried out on different gut tract: duodenum, ileum, caecum and colon. Glycohistochemistry was performed by staining with Periodic acid-Schiff (PAS), Alcian blue (AB) pH 2.5, AB-PAS, AB pH 1, AB pH 0.5, low iron diamine, high iron diamine. Adjacent serial sections were pre-treated with Sialidase V before staining with AB pH 2.5 (Sial-AB) preceded or not by saponification with 1% KOH in 70% ethanol to remove the acetyl groups (KOH-Sial-AB). BAX protein detection was performed by immunohistochemistry. Positive histochemical responses were observed at goblet cell level in all examined gut tracts; duodenal glands were also reactive. The statistical analysis of histochemical reactivity intensity evidenced significant differences between the dietary treatments. The most noticeable difference regarded the response to Sial-AB and KOH-Sial-AB histochemical analyses which induced differentiated behavior of goblet cells in the samples derived from O diets in which sialoglycoderivatives perform specific defense action. O diet increased the production of highly acid glycoconjugates in the gut which improve mucosal lubrication and the formation of a viscoelastic barrier, with an unspecific defense mean. Immunohistochemical analysis revealed a lower presence of BAX in the examined intestinal tracts of O group compared with CTR group. Findings show that OAE supplementation improves the production of the glycoconjugates able to enhance the protection of the pig intestinal mucosa. In addition, the reduced BAX immunostaining observed in O group swine respect to CTR group suggests an enhanced antioxidant action in oregano supplemented diet group. Outcome should be taken into account for studies aimed at enhancing defence ability in order to reduce antibiotic use and prevent antimicrobial resistance.