ABSTRACT: This experiment was conducted to investigate the effect of theabrownins (TB) on production performance, egg quality, and ovarian function of laying hens at different ages. A total of 240 Lohmann laying hens were assigned in a 2 × 2 factorial design, which encompassed 2 layers ages (47-wk-old and 67-wk-old) and 2 dietary levels of TB (0 and 100 mg/kg) for 12 wk. Results showed that older layers had lower laying rate, egg mass, and higher feed-to-egg ratio (F/E), egg weight and unqualified egg rate than the younger layers (P(AGE) < 0.01) during all the experimental period. The effect of TB was found to increase egg laying rate and feed efficiency during 5 to 8 wk, 9 to 12 wk and the overall phases and decreased unqualified egg rate during 1 to 4 wk and the overall phases (P(TB) ≤ 0.05). The eggshell quality (strength, thickness), albumen quality (albumen height and Haugh unit) of eggs from older layers were decreased during overall phases (P(AGE) ≤ 0.05). TB increased eggshell strength during all phases and enhanced eggshell thickness at the end of wk 4 and 8 and increased albumen height and Haugh unit at the end of wk 8 and 12 of older layers (P(Interaction) ≤ 0.05). In addition, TB also increased egg quality of older layers after 14 d storage. A decrease in the serum concentration of progesterone, melatonin, follicle stimulating hormone, estradiol was observed in the older compared to the younger ones (P(AGE) < 0.05), while the increase in serum concentration of progesterone, melatonin, anti-Müllerian hormone (AMH) were more emphasized when older hens received TB supplemented diet (P(Interaction) < 0.05). The older layer demonstrated lower the concentration of glutathione (GSH) (P(AGE) < 0.05). And the activity of glutathione-s-transferase (GST) was significantly decreased in layers under 67-wk-old (P(AGE)
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