From ponds to pastures: Azolla as a functional and climate-smart feed resource for poultry and livestock.

The escalating challenge of securing sustainable, climate-resilient feed resources necessitates the exploration of novel alternatives. This review critically evaluates the potential of Azolla, a small aquatic fern, as a functional and climate-smart feed ingredient for livestock and poultry. Owing to its symbiotic association with the nitrogen-fixing cyanobacterium Anabaena azollae, Azolla achieves rapid biomass accumulation without external nitrogen input, thereby offering a uniquely low-carbon low-cost cultivation system. Nutritionally, Azolla contains 15-35 % crude protein (dry matter), and serve as a valuable source of essential amino acids, vitamins, minerals, and diverse bioactive compounds that may contribute to improved animal health and product quality. Evidence from feeding trials in poultry and other livestock species consistently demonstrate that Azolla supplementation significantly enhance growth performance, feed efficiency, egg and milk production, immune functions, and overall product attributes, while simultaneously lowering feed cost. Notably, its bioactive profile supports gut integrity, antioxidant capacity, and methane mitigation, emphasizing its dual potential to improve productivity and reduce the environmental footprint of animal agriculture. Azolla's adaptability across agro-climatic zones and capacity for year-round cultivation further reinforce its suitability as a climate-smart feed resource. Despite these advantages, constraints related to large-scale production, preservation, nutrient variability, and the presence of anti-nutritional factors highlight the need for standardized cultivation protocols and innovative processing technologies. This review consolidates current evidence on the nutritional, functional, and ecological value of Azolla and identifies key research priorities to support its broader adoption as a sustainable feed resource for livestock and poultry.