Bentonite as a raw material
Bentonite is the trade and geological name for a clay deposit rich in smectite minerals, above all montmorillonite (described in detail on our montmorillonite page). It formed over geological time from volcanic ash deposited in water. The same name covers very different materials: deposits vary in smectite content, in the dominant exchangeable cation, and in the amount of accompanying minerals such as quartz, feldspar, calcite or other clays.
Türkiye has significant bentonite deposits, and bentonite is used in many industries besides feed, such as foundry sand, drilling mud, cat litter and civil engineering. Feed-grade bentonite is a selected and controlled grade of this raw material, not simply any ground clay.
Sodium bentonite, calcium bentonite and activation
Bentonites are usually classified by the cation that dominates the interlayer space of the montmorillonite.
- Sodium bentonite: swells strongly in water and forms viscous gels. It is valued as a binder and in drilling and sealing applications.
- Calcium bentonite: swells less and disperses less in water. Many deposits worldwide, including many used for feed, are calcium (or calcium-magnesium) bentonites.
- Soda-activated bentonite: calcium bentonite treated with sodium carbonate so that part of the calcium is exchanged for sodium, increasing swelling and binding behaviour.
- Acid-activated bentonite: treated with acid to increase surface area; mainly used as a bleaching earth in oil refining rather than in feed.
From quarry to feed-grade product
Feed-grade bentonite is produced by selective mining of suitable layers, drying to a controlled moisture, grinding and sieving to a defined particle size, and, where needed, activation. Because the deposit is natural, each lot must be analysed: the mineral composition, cation exchange behaviour and contaminants can vary within the same quarry. A consistent supplier controls both the deposit and the process, and issues a certificate of analysis for every lot.
What does bentonite do in animal feed?
In the EU, bentonite is authorised both as a technological additive (binder and anticaking agent) and, for bentonite meeting a defined specification, as a substance that reduces contamination of feed by aflatoxin B1. The conditions differ between these authorisations; local regulations and the product label always prevail.
- Pellet binder: helps hold particles together and supports pellet durability.
- Anticaking and flow agent: keeps powdered feeds, mineral mixes and premixes free-flowing.
- Carrier: in some premixes and additives it serves as an inert-like carrier for micro-ingredients.
- Aflatoxin binding: bentonites with high, well-characterised smectite content are used as the main component of toxin binders against aflatoxin B1. Their effect on Fusarium toxins such as DON and zearalenone is limited.
Quality criteria for feed-grade bentonite
- Smectite (montmorillonite) content: the key quality figure, determined by X-ray diffraction (XRD); methylene blue adsorption is often used as a routine indicator.
- Cation exchange capacity and swelling index: indicators of clay activity and of sodium or calcium character.
- Accompanying minerals: quartz and other non-active minerals dilute the product; respirable crystalline silica is also an occupational dust consideration.
- Heavy metals and dioxins: within the undesirable-substance limits of feed legislation.
- Moisture, particle size and bulk density: important for mixing, flow, pelleting and storage.
- Traceability: a certificate of analysis (CoA) and lot number for every batch.
CTF Premix and bentonite
Feed-grade bentonite and montmorillonite-based toxin binders are part of CTF Premix's product range, produced at our 10,000 m² facility in Ankara under ISO 9001:2015 and GMP. Requests for a particular bentonite type, particle size or use (binder, carrier or toxin binder) are evaluated by our technical team according to the intended application and target species. Every lot is traceable, 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.