Trace Mineral Function

Manganese. In general, manganese is an activator of enzyme systems in the metabolism of carbohydrates, fats, proteins and nucleic acids. Manganese also has multiple functions that relate to the synthesis of bone matrix (collagen) for skeletal growth and for joint function. Manganese is also involved in cholesterol synthesis and affects the metabolism of reproductive hormones.

Function of Manganese in Egg Production
For layers, a manganese deficiency primarily affects eggshell synthesis. Manganese is involved in collagen metabolism (collagen is a main constituent in eggshell membranes). It has been shown that a deficiency in manganese may lead to a reduction in collagen synthesis. Thus, this phenomenon could affect the protein matrix constituting the frame of the eggshell and the initiation of the crystallization of calcite.

Manganese influences eggshell structure. Manganese is believed to create a denser mineral frame providing more resistance and strength. Some studies using crystallography have been able to demonstrate this effect. Some in vitro trials have shown the influence of manganese on the shape of calcium carbonate crystals. The action of manganese on the calcification of the collagen is well known, since it is recognized in skeletal growth. It is therefore logical to believe the same mode of action may affect eggshell formation. This hypothesis tends to be confirmed with the presence of a non-collagenic bone phospho-protein inside the eggshell: osteopontine. Existing inside the uterine fluid, it may play a role in the formation of the calcified layer. However, studies have not yet confirmed the determining role of manganese in this mechanism.

It is also important to note that animals deficient in manganese during the growth period have been shown to have poor skeletal growth. Long bones are important as a mobilizable reserve of calcium used by the layer to produce the eggshell.

Antagonists to Manganese and Recommended Dietary Inclusion Rates
Manganese is one of the least toxic trace minerals. Dietary concentrations between 40 and 100 ppm are typically included in layer diets. Excesses in calcium intake (usual in layers) raise the inclusion rate of manganese because of increased fecal excretion of inorganic manganese.