In this experiment, the effects of fennel and thyme extracts with and without flaxseed were investigated on performance and egg quality of Leghorn-type laying hens (Hy-Line W-36). 200 laying hens from 26 to 38 weeks of age were assigned to five dietary treatments with five replications. The treatment groups were: 1) Control (a diet without any additives); 2) control diet plus fennel (40 mg/kg feed); 3) control diet plus thyme (40 mg/kg feed); 4) a diet containing flaxseed and fennel; and 5) a diet containing flaxseed plus thyme. There were significant differences in feed intake and egg weight between the treatments (P < 0.05). The egg yolk color index in hens that received thyme extract and flaxseed treatment was significantly higher than other treatments (P < 0.05). Hens fed control diet had lower Haugh unit compared to other treatments that contained herbal extracts. The eggshell strength was significantly higher in hens that received thyme extract and flaxseed treatments than control (P < 0.05). The eggshell weight in treatments containing flaxseed was significantly higher compared to the other treatments (P < 0.05). The lowest egg yolk cholesterol concentration was found in hens fed thyme and flaxseed treatment. The hens fed plant extracts and flaxseed diets had eggs with low palmitic and stearic acids and high α-linolenic acid. It is concluded that thyme and fennel extracts, as well as flaxseed, improved the performance and egg quality of laying hens. The use of flaxseed and thyme extract improved egg yolk omega-3 fatty acids and decreased yolk cholesterol content

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