Manganese

Functions
Since the early 1930s, manganese has been recognized
to be essential for numerous physiological funtions, mostly
growth and skeleton development. In the following decades,
it has been identified as playing a vital role in reproductive
performance and having an influence on the function of the
central nervous system.

Poultry
Its fundamental role with regard to prevention of perosis has
been well established. Also called slipped tendon illness,
perosis was responsible for massive mortality in chick breeding.
In addition, research has demonstrated the action of manganese
in calcium metabolism and hatchability.

Ruminant
Manganese deficiency in ruminant may cause physical weakness
and calves malformations such as stiffness or enlarged joints.

Pig
In deficiency situation, the probability of piglet mortality tends
to increase soon after birth. Males raised on a Mn deficient diet
are affected by sterility and sexual degeneration.

Manganese sources
Several chemical compounds of manganese can be used in animal feed.
They essentially include manganous oxide (MnO), and manganese salts
(sulphate, carbonate, chloride and phosphate).
In the production of pre-mixes and mineral feeds intended for breeding animals,
for economic reasons, MnO is the preferred source of inorganic manganese,
followed by MnSO4 in a proportion of around 90 % and 10 % respectively
in the Economic Union. There is practically no use of the other Mn salts,
except for very few targetted applications.

Quality parameters
Biological availability
This is an important factor when selecting sources of manganese.
Manganese oxide is soluble in the gastrics juices. This characteristic is
not a critical issue for the so called “water-soluble” manganese salts
(MnSO4 for instance), but well for the naturally “water-insoluble” manganese oxides.
Many studies demonstrate the influence of the ionic form of manganese oxides
on its metabolic absorption in animal physiology. They substantiate the fact that
best results are obtained with manganese oxides in valency II
(Mn++ from MnO).
This is why, it is recommended to specify the nature of the manganese oxide
and to guarantee, in addition to the total Mn content, the content of
MnO2 not to exceed 2 to 5 %.

Purity (undesirable elements)
There is no formal E.U. legislation applied for the trace minerals but it is
recommended to limit the content of the harmfull impurities
in Mn compounds as follows

	MnSO4.H2O	MnO
	(mg/kg)	(mg/kg)
Pb	< 25	< 100
As	< 25	< 120
Cd	< 25	< 20
Hg	< 5	< 5

Analytical methods

	method	brief description
total Manganese	potentiometric determination	- solubilisation by HCl - titration of Mn by a KMnO4 solution in presence of sodium pyrophosphate at neutral pH.
MnO2	potentiometrec determination	- reduction of MnO2 to Mn2+ with an acidic solution of Fe2+ in excess. - back titration of Fe2+ in excess by a KMnO4 titrated solution.
Na / K / Mg / Ca	spectro-photometric atomic absorption (SAA)	HCl dissolution / filltration / dosage by SAA
Ni/Cu/Co/Fe/Pb/Cd	SAA	HCl solubilisation / fusion / dosage by SAA
As	ICP	solubilisation by oxidative attack / dosage.

General criteria for selection
- total manganese assay
- guaranteed maximum content of MnO2 (criteria for good bio-availability)
- chemical and physical stability
- toxicity (lead, arsenic, cadmium, mercury)
- physical aspect

off-white crystals or micro-granules

dark brownish-green powder