Seaweed is safe for most animals and trials over the past 20 years show seaweed can be up to 10% of animal feed without any issue. Some seaweed (e.g. Asparagopsis species) are being researched in ruminants to prevent methane production in ruminants. Most recent studies have shown strong animal health outcomes and in some trials replacement of Zinc and / or antibiotics.
For centuries, seaweed has been a component of diet to animals and humans. Most studies show increased growth rates, improved health and well-being.
Exceptions
Some fresh water turtles and reptiles may have some adverse effects from seaweed as seaweed has high levels of potassium (K). While there is no data in the literature, potassium is generally in the range of 2 to 8 mmol/l. Hypokalaemia in reptiles will occur from inadequate intake or excessive loss (diarrhoea). In mammals, hyperkalaemia may occur with excessive potassium intake, decreased secretion or shift from intracellular to extracellular fluid (e.g. severe acidosis)