Effects of Dietary Oregano Essential Oil on Cecal Microorganisms and Muscle Fatty Acids of Luhua Chickens

SIMPLE SUMMARY: As a natural substitute for antibiotics, oregano essential oil is a feed additive drug approved by the Ministry of Agriculture, which can improve animal production and health. There are few reports on the combination of quinoa and oregano essential oil used in animal production for feed development and utilization. Therefore, the aim of this study was to analyze the effects of different proportions of oregano essential oil in a corn–quinoa–soybean meal diet on the intestinal microbiota and muscle fatty acids of Luhua chickens. The results showed that the addition of oregano essential oil to the corn–quinoa–soybean meal diet effectively improved the microbial community composition in the caecum of Luhua chickens, enriching the related pathways, so as to promote the digestion and absorption of nutrients and enhance intestinal barrier functioning. It significantly improved the content of some fatty acids in the muscles of Luhua chickens, and there was a certain correlation between cecal microorganisms and fatty acid deposition in muscles. These data provide a theoretical basis for the scientific application of oregano essential oil and quinoa in the feeding and fodder development of Luhua chickens. ABSTRACT: This experiment was conducted to investigate the effects of oregano essential oil on the cecal microorganisms and muscle fatty acids of Luhua chickens. One hundred and twenty 49-day-old healthy dewormed Luhua chickens were randomly divided into four groups with three replicates per group and ten chickens per replicate. The corn–quinoa and soybean meal diets were supplemented with 0 (Q8 group), 50 (QO50 group), 100 (QO100 group) and 150 mg·kg(−1) (QO150 group) of oregano essential oil, respectively, and the experiment lasted for 75 days. The composition of intestinal flora was detected by Illumina sequencing of the 16S rRNA V4 region, and the composition and content of fatty acids in the muscles were analyzed by gas chromatography. The results showed that dietary oregano essential oil can effectively increase the contents of elaidic acid (C18:ln9t), polyunsaturated fatty acids (PUFAs) and n-3 polyunsaturated fatty acids (n-3 PUFAs) in breast muscle tissues. However, the fatty acid composition and PUFA content in leg muscle tissues were not significantly improved. According to a 16S rRNA high-throughput sequencing analysis, dietary oregano essential oil supplementation with a certain concentration can change the cecal microbial community composition of broilers. At the phylum level, Elusimicrobia in the QO150 group was significantly lower than that in Q8 group (p < 0.05). At the genus level, Phascolarctobacterium, Parasutterella and Bilophila in the experimental groups (QO50, QO100 and QO150) were significantly lower than those in the Q8 group (p < 0.05). An enrichment analysis of the microbial function found that the amino acid metabolism, energy metabolism, metabolism, signal transduction and genetic information processing were mainly enriched in the experimental groups, which promoted the digestion and absorption of nutrients and enhanced intestinal barrier functioning. An analysis of the association between fatty acids and microbes found that the abundance of microbiota was significantly correlated with partially saturated fatty acids (SFAs) and unsaturated fatty acids (UFAs) (p < 0.05). In conclusion, the dietary addition of oregano essential oil can effectively improve cecal microbial community composition, promote the digestion and absorption of nutrients, and enhance intestinal barrier functioning. It can significantly improve the content of some fatty acids, and there was a certain correlation between caecum microorganisms and fatty acid deposition in muscles.