Oregano Essential Oil and Purple Garlic Powder Effects on Intestinal Health, Microbiota Indicators and Antimicrobial Resistance as Feed Additives in Weaning Piglets

We studied the impact of the bioactive components degradation of oregano essential oil and purple garlic powder during storage in silos, their effect on the morphometry of the jejunum and ileum and the cecal microbiota as intestinal health indicators in the piglets during the post-weaning. We also monitored antimicrobial resistance in the commensal indicator Escherichia coli. Histological parameters and intestinal microbiota were measured in 140 piglets weaned at 21 days of age. Seven dietary treatments were used: a negative control group (basal diet), a positive control group with zinc oxide (3000 mg/kg of food), two groups with oregano essential oil at 0.4% and 1.2%, respectively, two groups with purple garlic powder 0.4% and 2%, respectively, and a group with oregano essential oil with 1.2% combined with purple garlic powder with 2%. Each group of piglets received the treatment for seven weeks, from weaning, before samples were taken. Antibiotic resistance profiles were studied in 81 Escherichia coli strains from the cecal content. A progressive loss of the bioactive components of oregano essential oil and purple garlic powder was observed during the 34 days of storage. With purple garlic powder at 2% and oregano essential oil at 1.2%, their combination showed results like zinc oxide and even superior results in terms of the histological parameters studied and the counts of Escherichia coli and Lactobacillus. We observed high levels of resistance to antimicrobials of all categories. In general, the high doses of the additives studied showed the best results, obtaining levels like or higher than those offered by zinc oxide.