This study investigated the effect of seaweed supplementation in dairy cow diets on milk yield, basic composition, and mineral concentrations. Thirty-seven Icelandic cows were split into three diet treatments: control (CON, no seaweed), low (LSW, 0.75% concentrate dry matter (DM), 13–40 g/cow/day), high (HSW, 1.5% DM, 26–158 g/cow/day). Cows fed same basal grass silage for a week, then introduc...