Dietary theabrownins alleviate age-related declines in productive performance and egg quality by improving intestinal health in laying hens.

BACKGROUND: The late laying period is often accompanied by declines in productive performance, egg quality, and intestinal health in hens. This study used a 2 × 2 factorial design to evaluate the effects of dietary theabrownins (TB), bioactive polyphenols derived from dark tea, on production performance, egg quality, intestinal health, and cecal microbiota in 47- and 67-week-old laying hens. A total of 192 Lohmann Gray hens were fed diets containing 0 or 100 mg/kg TB for 12 weeks. RESULTS: Significant age × TB interactions were observed for average daily feed intake (ADFI; P = 0.005), eggshell thickness (P = 0.001), jejunal villus height (P = 0.005), and TJP2 expression (P = 0.029). Compared with 47-week-old hens, 67-week-old hens had higher egg weight, feed-to-egg ratio, and unqualified egg rate, but lower laying rate, egg mass, Haugh unit, and eggshell strength (all P < 0.01). TB supplementation increased laying rate (P < 0.001), egg mass (P = 0.003), Haugh unit (P = 0.015), eggshell strength (P = 0.010), and albumen height (P = 0.018), while reducing feed-to-egg ratio (P = 0.003). TB also improved jejunal morphology by increasing villus height and reducing crypt depth, enhanced antioxidant capacity by increasing T-AOC (P = 0.002) and GST activity (P = 0.025), and upregulated jejunal TJP2 expression in older hens. In addition, TB decreased the Firmicutes/Bacteroidota ratio (P < 0.001) and enriched Prevotellaceae_UCG-001 abundance. Notably, correlation analysis showed that Prevotellaceae_UCG-001 was positively correlated with intestinal antioxidant indices, whereas productive and egg quality traits were significantly associated with intestinal structural and functional indicators. CONCLUSION: Dietary TB supplementation partly alleviated age-related declines in productive performance and egg quality in laying hens, possibly through improving intestinal health and modulating cecal microbiota. Notably, the TB-enriched genus Prevotellaceae_UCG-001 was positively associated with intestinal antioxidant indices, suggesting a potential microbial link to the intestinal benefits of TB in aged laying hens. These findings support the potential application of TB as a functional feed additive to help maintain intestinal health and productive performance in aged laying hens.