Abstract
This study investigates the effects of Castanea sativa (chestnut) supplementation on egg quality in laying hens fed low-protein diets. Three dietary treatments were evaluated: control (CON), low-protein diet (LPD), and low-protein diet supplemented with Castanea sativa (LPC). Egg physical traits, internal and external quality parameters, chemical composition, antioxidant profile, and shelf-life under two storage temperatures (5°C and 22°C) were assessed. Castanea sativa demonstrated notable nutritional and antioxidant properties, with high levels of vitamin E (124.80 mg/kg), total phenolic content (45.68 mg/g GAE), and DPPH antioxidant activity (167.52 mM Trolox). Castanea sativa supplementation improved total polyphenol content in egg yolks (LPC = 0.52 mg/g GAE vs. CON = 0.25 mg/g GAE), increased eggshell breaking strength (LPC = 5.14 kgF vs. CON = 4.07 kgF), and maintained comparable levels of crude protein and fat. After 30 days at 22°C, LPC eggs retained higher albumen height (3.61 mm) and Haugh units (53.35) compared to CON (3.12 mm and 48.28, respectively), indicating better freshness. Similarly, yolk index was more stable in LPC (0.24) versus CON (0.22). At 5°C, all groups preserved quality better, but LPC still showed advantages in shell strength and yolk height (17.14 mm vs. 16.57 mm in CON). Compared to initial values, egg weight and albumen quality as expected, declined during storage across all treatments, especially at 22°C. However, LPC eggs exhibited the least deterioration, highlighting the protective role of Castanea sativa. These findings suggest that chestnut supplementation enhances egg antioxidant stability, maintains structural integrity, and egg quality during storage, offering a functional nutritional strategy for hens on protein-restricted diets.