The effects of dietary oregano essential oil on production, blood parameters, and egg quality of laying hens during the early lay phase

Essential oils can be used as an alternative to antibiotics for health promotion in livestock. The essential oil of oregano (EOO) can have positive effects on poultry. This study aimed to explore the effects of EOO on performance, blood lipid profile, antioxidant capacity, and egg quality in Hy-line Brown layers during the peak laying phase. A total of 270 hens at 24 weeks of age were given, at random, a corn-soybean-based control diet, or the diet supplemented with a commercial EOO product (275 mg/1 kg control diet). Feed and bird weights and egg quality were measured at 24, 30, 36, and 40 weeks while blood samples were taken at 24, 36, and 40 weeks. Differences were measured between treatments and across weeks using generalised linear mixed models and Tukey’s posthoc test for significant differences (α = 0.05) in R 3.3.1. Feed conversion ratio was lower in EOO at 30 and 40 weeks than in control birds (P < 0.05). At 24 and 36 weeks, certain blood lipids- triglycerides and cholesterol- were significantly lower while high-density lipoproteins were significantly higher in hens supplemented with EOO (P < 0.05). Antioxidant parameters, including total antioxidant capacity and antioxidant enzymes, were higher at all timepoints in the oregano group compared to the control at all timepoints (P < 0.05). The measure of lipid peroxidation was statistically lower at all timepoints in EOO birds (P < 0.05). Indicators of liver health were significantly lower at certain ages in the EOO group compared to the control group. Indicators of internal egg quality were significantly higher in eggs from the EOO group (P < 0.05), but no differences in external quality were identified. Lastly, levels of egg yolk lipid peroxidation were lower in EOO eggs compared to the control at all timepoints (P < 0.05). In conclusion, oregano essential oil has many benefits, and it may be one potential source of health enhancement in laying hens. Oregano essential oil may be a good option for producers to maximise their flock longevity and enhance potential profit from eggs.