Supplementing Oregano Essential Oil in a Reduced-Protein Diet Improves Growth Performance and Nutrient Digestibility by Modulating Intestinal Bacteria, Intestinal Morphology, and Antioxidative Capacity of Growing-Finishing Pigs

Abstract

Simple SummarySerious nitrogen pollution and shortage of protein feed resources have constrained the rapid development of the pig industry. Thus, the strategy of using a reduced-protein diet supplemented with amino acids in pig production has been widely accepted. Additionally, antibiotic growth promoters have been widely used in pig production for many years. However, their enormous and uncontrolled use has promoted bacterial resistance, leading to less effective treatment for animal diseases. Accordingly, this study investigated the effects of inclusion of oregano essential oil in a reduced-protein, amino acid-supplemented diet on growth performance, nutrient digestibility, gut health, and antioxidative capacity of growing-finishing pigs as an alternative to antibiotics. Our results suggested that adding oregano essential oil to a reduced-protein diet improved the growth performance and carcass lean percentage of pigs. In addition, long-term supplementation of oregano essential oil to a reduced-protein diet improved the intestinal bacteria, intestinal morphology, and antioxidative capacity of pigs. This study provides theoretical guidance for application of low-protein diet to guide the production of antibiotic-free feed for growing–finishing pigs.AbstractThis study investigated the effects of supplementing oregano essential oil (OEO) to a reduced-protein diet on growth performance, nutrient digestibility, intestinal bacteria, intestinal morphology, and antioxidative capacity of growing-finishing pigs. Forty-eight barrows were randomly allotted to four treatments including normal-protein diet (NPD), reduced-protein, amino acid-supplemented diet (RPD), the same RPD supplemented with chlortetracycline (RPA), and RPD supplemented with OEO (RPO). The data showed that dietary OEO supplementation increased the average daily gain of pigs compared with NPD and RPD. The gain:feed in RPO- and NPD-fed pigs was higher than those in RPD- and RPA-fed pigs. Increased average daily feed intake and 10th-rib backfat thickness were detected in RPA-fed pigs. Pigs fed the RPO had higher apparent total tract digestibility (ATTD) of crude protein than those fed the other diets. The RPD and RPA treatments showed reduced counts of Lactobacillus spp. in ileal digesta of pigs. The RPA and RPO treatments also showed lower Escherichia coli counts in ileal digesta than the NPD and RPD treatments. Dietary OEO supplementation increased villous height of the jejunum and the ileal and plasma total antioxidative capacity of pigs. In conclusion, dietary OEO supplementation could improve the growth performance and nutrient digestibility of pigs by modulating intestinal bacteria, intestinal morphology, and antioxidative capacity.

Allium Extract Implements Weaned Piglet’s Productive Parameters by Modulating Distal Gut Microbiota

“…Different plant extracts improve animal performance, productive parameters, and induce changes in gut microbiome of animals. For instance, oregano oil in growing-finishing pigs improved growth performance and nutrient digestibility by modulating gut microbiota [ 47 ], and oregano oil had been also used together with carbohydrases in piglets, improving feed conversion ratio with respect to control and antibiotic growth promoter diets [ 23 ]. Other essential oils obtained from thyme and cinnamon improved body weight of weaning pigs and decreased the number of pathogens as E. coli in different gut regions [ 22 ]; and a mixture of essential oil from mint and cinnamon improved feed efficiency in piglets [ 24 ].…”

Effects of Dietary Supplementation of Garlic and Oregano Essential Oil on Biomarkers of Oxidative Status, Stress and Inflammation in Postweaning Piglets

“…Research has been carried out on the effect of supplementation with OEO on the oxidative status in plasma and muscles of growing-finishing pigs, in the semen of boars, and in porcine small intestinal epithelial (IPEC-J2) cells in vitro. The anti-inflammatory effect of OEO has been associated with decreased cellular levels of reactive oxygen species (ROS), biomarkers of stress, such as cortisol, and biomarkers of inflammation, such as acute-phase proteins [47][48][49][50][51][52]. We hypothesized that garlic powder and OEO as feed additives at appropriate doses could improve the oxidative status, stress, and inflammation in weaned piglets.…”

Essential Oils as a Feed Additives: Pharmacokinetics and Potential Toxicity in Monogastric Animals

“…The results of some studies demonstrated the efficacy of EOs as feed additives in animal breeding [25]. However, we have found several articles that address their potential toxicity.…”