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

Abstract

Abstract 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.