Quercetin as a bioactive feed additive: nutritional, antioxidant, and gut health implications in poultry and rabbits.

Quercetin is a bioactive flavonoid widely distributed in vegetables, grains, and fruits, known for its powerful anti-inflammatory, immunomodulatory, and antioxidant properties. Recently, it has attracted increasing attention as a sustainable and functional additive in animal nutrition. This review explores the existing understanding of the use of quercetin in poultry and rabbit diets, focusing on its impact on growth efficiency, intestinal health, antioxidant, immune function, and the quality of animal-derived foods. In rabbits, dietary supplementation with quercetin (25-100 mg/kg diet) has been associated with enhanced feed efficacy, meat composition, and gut microbial balance. In poultry, including broilers and laying hens, quercetin (up to 200 mg/kg) enhances growth under normal and heat stress conditions, improves meat and egg quality, and modulates oxidative stress markers and gut microbiota. These effects are connected to how quercetin helps control the activity of genes that deal with inflammation, antioxidant enzymes, and the immune system in the gut. Importantly, the review emphasizes the potential of quercetin to improve the nutritional and functional quality of meat and eggs, making it highly relevant for human health and food sustainability. Further studies are encouraged to define optimal dosages and explore synergistic effects with other natural additives. This review offers critical insights into how dietary quercetin can be utilized to support animal health, efficiency, and food product quality, aligning with the global shift toward natural, residue-free feed strategies.