Archives of Current Research International

Seaweeds are increasingly investigated as functional feed resources, yet extrapolation from biochemical activity to better animal health, productive efficiency and environmental performance remains uncertain. This critical narrative review integrates evidence for macroalgal meals, extracts and characterised metabolites in finfish, broiler chickens, laying hens and ruminants, with particular attention to mechanisms, exposure, product safety and sustainability. Peer-reviewed studies and relevant methodological reviews published between 2014 and 12 August 2026 were considered through accessible scholarly indexes, citation searching and journal records. Across animal systems, responses depend on algal taxonomy, growing conditions, processing, dietary concentration, basal ration and physiological context. In fish, changes in innate immune markers and intestinal characteristics are more consistently reported than durable improvements in growth or disease resistance; a tilapia meta-analysis found no significant overall growth or feed-conversion advantage for seaweed-containing diets. In poultry, some controlled studies and a small meta-analysis indicate improvements in performance or intestinal indices, whereas trials in breeders identify limited reproductive benefits and potential iodine transfer. In ruminants, bromoform-containing Asparagopsis can substantially suppress enteric methane, but effects differ between housed and grazing settings, may diminish with storage or prolonged feeding, and can coincide with lower feed intake or increased iodine and bromide in milk. Across systems, contaminant speciation, mineral transfer, feed palatability, resource use and the emissions of cultivation and processing constrain claims of sustainability. The most defensible conclusion is that particular, quality-controlled seaweed preparations can deliver defined functional effects in particular production contexts; seaweed inclusion as a general strategy for healthier animals and climate-neutral production is not established. Research should prioritise exposure-standardised trials, clinically meaningful outcomes, residue surveillance, farm-scale replication and consequential environmental assessment.