Feed Solutions
CHELATED MINERALS, COMPLEXES AND INORGANIC SALTS Authors: Giovanni Predieri Roberto Barea Silvia Peris
D
uring the first decade of this century, a large number of studies have shown that the bioavailability of trace elements can be improved when they are supplemented as chelates (Jondreville and Revy, 2003; Ballarini and Predieri, 2007; Liu et al., 2014). The benefits provided by chelated minerals with respect to inorganic sources can be attributed to: (a) absence of free metal cations (Fe2+, Mn2+, Cu2+, etc.) responsible for feed deterioration through free radicals formation; (b) protection of minerals from interaction with phytates and oxalates and from antagonism with other minerals; and (c) less mineral excretion into the environment. The classification of the trace elements according to the Register of Feed Additives of the
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EU is not the ideal since the chemical nature of the different mineral additives is not taken into account. In fact, not all amino acid (AA) and mineral aggregations lead to chelated compounds (Ballarini and Predieri, 2007). This forces us to make a better distinction between mineral complexes and true chelates. The nature of the chemical bond The chemical bond is the mutual attraction between atoms that allows the formation of chemical compounds. Depending on the nature of the atomic interactions, three categories of chemical bonds exist in nature: ionic, covalent, and metallic (the latter will not be described in this article). An ionic bond forms when oppositely charged ions (anions
and cations) attract each other. This type of bond occurs between metals (cations: Zn, Ca, Mn, etc.) and non-metal (anions: S, O, etc.). A covalent bond is characterized by the exchange of one or more pairs of electrons between atoms. A special type of this bond is the dative, or coordinated, covalent bond, which occurs when one atom gives both electrons (donor) to another atom that receives them (acceptor). Chelates are special complexes Coordinated covalent bonds can produce chelates (chele = clamps), if the arrangement of donor atoms around the mineral forms a chelation ring (Figure 1). From the chemical point of view, there are four main classes of “organic” minerals marketed in feed
January-February 2022
