Whether iron in montmorillonite can affect Vitamins absorption in feed especially easily oxidized vitamin A, to analyze from two aspects:

◆The effect of iron on vitamins under the condition of feed storage

◆◆Speciation of iron in montmorillonite and release conditions of iron ions

I. The effect of iron on vitamins under the condition of feed storage

The main source of iron element during feed production is to add Ferrous sulfate dihydrate salt, however, in the room temperature storage conditions,Vitamins is mainly affected by moisture、temperature、trace mineral elements、choline、carrier 、 sustained release and time etc. In terms of Vitamin A,mainly is affected by light, oxidation and heavy metal ions, generally believed that humidity is only less sensitive to vitamin A, but there are greater impacts with others factors( metal ions、choline、high temperature etc).Most scholars believe that Fe, Cu, Zn are main factors to influence Vitamin stability,the presence of moisture and fat to accelerate the reaction rate, the destruction may be associated with these elements catalytic free radicals and chain reaction.

Cuili(1999)^【1】thought most Vitamin additive is unstable on trace mineral elements especially exist in form of sulfate.

Cheng zhonggang etc (2002)^【2】thought, mineral salt damage Vitamin A seriously, especially Sulfate,during the storage of three months, lost almost a third, the average monthly loss rate of 11.0%, but oxide is less than half of sulfate.

Liu danghui(1999)^【3】study showed that seven water ferrous sulfate and ferrous sulfate nine water have greater impact on vitamin A retention rate.The reason is not only the sole effect of iron ion or water, likely to be both interaction.

So, during the storage of feed, in the humidity conditions, Ferric ferrous sulfate Fe²⁺ has degradation effect on vitamin, however, iron elements existed in the form of oxide or Fe-Mn-bound in feed montmorillonite,it won’t dissociate Fe²⁺ 、Fe³⁺ during the storage, so there is no impact on Vitamin.

II. Speciation of iron in montmorillonite and release conditions of iron ions

Montmorillonite is composed of a volcano of glass material formed by hydrolysis of devitrification , or transformed by silicate minerals by alteration, another generation method is direct crystallization by silicon and aluminum gel.  It can be separated by three types,that is Volcano sedimentary type, weathering residual type and hydrothermal type.

Montmorillonite is a kind of natural mineral, it’s a clay mineral with complicated chemical structure, international clay institute confirmed it to be montmorillonite group. This group consists of two subfamily , that is two eight surface and three eight surface .

Iron and others metal elements in montmorillonite combined with different components form different chemical forms, it has close related to montmorillonite type, montmorillonite property, environment and conditions etc. Various form amount reflects the amount of the difference of its chemical properties of montmorillonite.It can be divided into water soluble, exchangeable, carbonate, Fe-Mn oxide bound, bound and residual organic state.Iron mainly exists in the form of Fe-Mn oxide phases、oxidant, combined residual state of aluminosilicate mineral lattice. If destroying Fe-Mn oxide is to make iron extract iron ion, it need to use Ammonia and hydrochloric acid complexing agent shaken 16 hours at room temperature;Combined residual state in Aluminosilicate mineral lattice , iron can dissociate iron ion with the method of Composite acid microwave digestion.【Continuous extraction method of Montmorillonite metal form (EU)】

It sees that iron ions are not released in the gastric acid. Conversely consider, if it can destroy lattice and release iron ions in the conditions of gastric acid,in that way, montmorillonite lattice is destroyed, it won’t have the capacity to adsorb mycotoxins.

Thus, feed containing montmorillonite is impossible to dissociate iron ion in the normal storage condition and in the gastric acid. So, iron in montmorillonite is irrelevant to oxide on Vitamin and lose nutriments on Vitamin.