Effect of Supplemental Oregano Essential Oils in Diets on Production Performance and Relatively Intestinal Parameters of Laying Hens

This study was designed to investigate the effects of dietary oregano essential oils on 150 30-week-old Hy-Line Layers’ productive performance, egg quality characteristics, cecal microbiota, digestive enzyme activities, mucosa structure of the duodenum and jejunum and glucose and small peptides transporters expression in the duodenum and jejunum. All hens were allocated into one of five different groups: negative control (NC; basal diet only), antibiotics control (CS; basal diet plus 100 mg/kg of 10% colistin sulfate) and treatments I, II, and III (basal diet supplemented with 50, 100 and 150 mg/kg oregano essential oils, respectively). The results showed that the laying rate, average egg weight, feed conversion ratio and the activities of amylase and trypsin were significantly improved by a diet supplemented with 100 mg/kg oregano essential oils (P < 0.01). The addition of oregano essential oils increased the number of intestinal Bifidobacterium and Lactobacillus significantly (P < 0.01), whereas the number of intestinal Escherichia coli and Salmonella was significantly (P < 0.01) decreased. The addition of 100 mg/kg oregano essential oils increased duodenum villus height (P > 0.05), significantly increased duodenum villus-height-tocrypt-depth ratios (P < 0.01) and decreased crypt depth in the duodenum (P < 0.05). Furthermore, the glucose transporter 2 (GLUT2), peptide transporter 1 (PepT1) and sodium-glucose cotransporter 1 (SGLT1) gene expression levels in the duodenum and jejunum were significantly increased in laying hens on a diet supplemented with 100 mg/kg oregano essential oils (P < 0.01). However, egg weight, relative eggshell weight, yolk index and Haugh unit value were not significantly affected by the addition of oregano essential oils (P > 0.05).