Seaweed

Seaweed, a general term for various species of macroalgae, includes red, green, and brown algae commonly harvested from marine environments. In equine feed, seaweed is used primarily as a natural source of trace minerals, particularly iodine, along with other nutrients such as calcium, magnesium, potassium, and certain vitamins.

Commonly used species in feed formulations include Ascophyllum nodosum (a type of brown seaweed), Laminaria digitata, and Chondrus crispus (also known as Irish moss).

Seaweed is typically dried and ground into meal or powder form for inclusion in feeds. It may also be processed into extracts or concentrates to standardize nutrient content, particularly for iodine levels.

While seaweed can be a beneficial supplement, excessive intake—especially of iodine-rich species—can pose a risk of iodine toxicity in horses. Therefore, its inclusion in equine diets should be controlled and formulated with attention to total dietary iodine content.