Oregano Feed Supplementation Affects Glycoconjugates Production in Swine Gut

SIMPLE SUMMARY: The European ban towards antibiotics is increasing the number of studies on the effects of feed additives, such as plant extracts, in order to enhance the health and welfare status of domestic animals intended for human consumption. Origanum vulgare possesses multiple pharmacological characteristics and its antioxidant and antibacterial properties are particularly interesting. Besides, a recent study aimed at evaluating the effects of oregano aqueous extract supplementation in poultry nutrition gave encouraging results regarding the secretion of glycoconjugates in the gut which increases tissue hydration and protects the intestinal mucosa from pathogenic bacteria, viruses, and parasites. Therefore, we investigated the effects of oregano feed supplementation on antioxidant and defense ability of pig gut. Our results showed that there was improved production of glycoconjugates in the duodenum and colon of pigs fed with supplementation of oregano aqueous extract, enhancing protection of the mucosa of these sections of the intestine. Also, we observed an enhanced antioxidant action in the two examined gut tract samples of the group supplemented with oregano. Findings can be used in further research to identify ways to improve endogenous defense ability with to reduce antibiotic use and prevent antimicrobial resistance. ABSTRACT: This study evaluated the effects of adding oregano aqueous extract (OAE) to the diet of pig slaughtered at finisher stage. Study was performed to identify glycoconjugates and evaluate the oxidative stress levels in the duodenum and colon intestinal tracts. 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, and high iron diamine. Serial sections were pre-treated with sialidase V before staining with AB pH 2.5 (Sial-AB) preceded or not by saponification. To study oxidative stress, an immunohistochemical analysis was applied to investigate the presence of the oxidative stress target molecule Bcl-2 Associate X protein (BAX). Findings show that oregano aqueous extract supplementation improves the production of the secretion glycoconjugates involved in direct and indirect defense, thus enhancing the protection of the pig intestinal mucosa. Moreover, the reduced BAX protein immunostaining observed in both duodenum and colon of swine of the oregano-supplemented group respect to that observed in the control group suggests an enhanced antioxidant action by oregano adding. Findings could be useful for other studies aiming to reduce antibiotic use and prevent antimicrobial resistance.