In its Scientific Opinion on the safety and efficacy as a technological feed additive the European Food Safety Authority has considered the use of bentonite as being safe for all animal species.
Bentonites are colloidal clays composed largely of montmorillonite. They are currently authorised for use as feed additives (binders, anti-caking agents and coagulants) to a maximum of 20 g/kg feedingstuffs.
Chickens and piglets tolerated the addition of bentonite at a concentration of 3 % of diet and dairy cows tolerated 2 % added bentonite. Trout are reported to tolerate at least 2.5 % bentonite in the diet.
Since the application is for all animal species and all bentonites, and as a margin of safety is difficult to establish, the FEEDAP Panel considers that the presently authorised limit of 2 % of diet should be retained.
Addition of bentonites to diets is incompatible with the use of robenidine and is expected to reduce the effectiveness of other coccidiostats.
Bentonites can increase pellet durability when added to complete feed at concentrations of between 1 % and 2 %. Since bentonites are authorised for use, without restriction, as anti-caking agents in food and can be assumed to demonstrate similar properties when applied to feed materials, no further demonstration of efficacy is considered necessary.
Bentonites added to feed contaminated by radioactive fallout or made available to grazing animals will reduce levels of radiocaesium in animals and their products.