What is montmorillonite?
Montmorillonite is a layered aluminosilicate mineral made of one alumina sheet between two silica sheets (a 2:1 structure). Water and exchangeable cations (sodium, calcium, magnesium) sit between the layers, giving the mineral a large surface area, the ability to swell and a high cation exchange capacity.
In nature it is usually found in bentonite deposits formed from weathered volcanic ash. The quality of clay sold as "bentonite" depends largely on how much montmorillonite it contains.
What does it do in animal feed?
The interlayer spaces and surface charge of montmorillonite allow it to hold certain molecules in the digestive tract. This works best for flat, polar mycotoxins such as aflatoxins.
- In toxin binders: helps bind aflatoxin B1 in the digestive tract and reduce its absorption.
- In pellet production: acts as a natural binder that improves pellet durability.
- Flowability and anti-caking: improves the flow of powders and premixes.
- As a carrier: used in some premix and additive products as a carrier for micro-ingredients.
Which mycotoxins does it work on?
Montmorillonite-based binders bind aflatoxins well. Their effect on mycotoxins such as deoxynivalenol (DON), zearalenone (ZEN), fumonisins and T-2 toxin is limited. Where these mycotoxins are a risk, regular testing, good storage and, where needed, products with other modes of action should be considered.
Quality criteria for feed-grade montmorillonite
- Montmorillonite (smectite) content: a high level is the main indicator of binding capacity. In the EU, bentonite authorised as a mycotoxin binder must contain at least 70% smectite.
- Cation exchange capacity (CEC) and swelling index: indicators of the clay's activity.
- Heavy metals and dioxins: must comply with the undesirable-substance limits in feed legislation.
- Moisture and particle size: important for mixing uniformity and storage stability.
- Traceability: a certificate of analysis (CoA) and lot number for every batch.
Points to consider in use
The inclusion rate depends on the product, the target species and the level of mycotoxin risk. In the European Union, bentonite authorised to bind aflatoxin B1 (1m558) has a maximum of 20,000 mg/kg (2%) in complete feed, and its conditions of use include avoiding simultaneous oral use with certain macrolide antibiotics. Always follow the regulations in your country and the product label.
CTF Premix and montmorillonite
CTF Premix produces montmorillonite-based toxin binders and feed-grade bentonite at its 10,000 m² facility in Ankara under ISO 9001:2015 and GMP. Every lot is analysed and traceable by lot number, and its certificate of analysis can be viewed on the batch verification page.
This page is for general information. Inclusion rates and product choice should be decided with a nutritionist, taking into account the species, the feed formulation and the applicable regulations.