Nutritional enrichment of eggs through essential oil–supplemented laying hen diets and associations with intestinal microbiota

This study evaluated the effects of oregano essential oil alone and in combination with cinnamon and peppermint essential oils on intestinal microbiota, the sensory and textural properties of cooked egg's and fatty acid profile. Intestinal microbiota/fatty acid profile correlations and health index were evaluated. Lohmann LSL-LITE strain laying hens were randomly divided into four groups and fed for 28 days: a control group receiving a basal diet (C); a group supplemented with 250 mg/kg oregano essential oil (O), a group receiving 125 mg/kg oregano plus 125 mg/kg cinnamon essential oils (O + C), and a group receiving 125 mg/kg oregano plus 125 mg/kg peppermint essential oils (O + P). Sensory evaluation showed that the distinctive flavors and aromas of oregano, cinnamon, and peppermint essential oils were not detected. Essential oil supplemented diet did not affect the eggs' hardness, adhesiveness, cohesiveness, and resilience properties. Shear force was found to be significantly different in group O. Assessment of nutritional indices showed that high Linoleic Acid/α-Linolenic Acid ratio has given O and O + P groups eggs potential functional properties. While the coliforms, Enterobacteriaceae, and Enterococcus spp. in the essential oil supplemented groups were reduced, and Lactobacillus spp. increased. Also, essential oil feed achieved a correlation between lactic acid bacteria and Linoleic Acid/α-Linolenic Acid, omega6/omega3 ratio. Furthermore, behenic, palmitoleic, and palmitic fatty acids positively correlated with intestinal Lactobacillus spp. As a result, laying hens feed essential oil supplementation results in potential functional eggs that offer better nutritional indices for the consumer health, which were obtained without affecting the egg's characteristics.