This study from China suggests that dietary manganese supplementation can improve eggshell quality by enhancing the synthesis of key compounds in the eggshell glands, which can affect the ultrastructure of eggshells.

Researchers from the Chinese Academy of Agricultural Sciences in Beijing study investigated the effect of dietary manganese supplementation on eggshell quality, ultrastructure, glycosaminoglycan (GAG), and uronic acid content, and mRNA and protein expression of Galβ1,3-glucuronosyltransferase (GlcAT-I).

In their paper published in Poultry Science, J.F. Xiao and colleagues explain that a total of 216 layers (Hy-Line Grey) at age of 50 weeks were divided into three groups. In the first eight weeks of the 12-week feeding trial, all groups were fed a basal diet that met all layer nutrient requirements except for manganese.

In the last four weeks, each group was fed one of three diets supplemented with manganese levels at 0, 25 or 100mg Mn per kg.

Dietary manganese deficiency did not affect the egg performance of layers.

Dietary manganese supplementation significantly improved the breaking strength, thickness and fracture toughness of eggshells.

In photographs of eggshell ultrastructure, the size of mammillary cones and cracks in the outer surface were decreased by dietary manganese supplementation.

The contents of GAG and uronic acids in eggshell membrane were significantly increased by dietary manganese addition. This result was further confirmed by increased mRNA expression and protein expression of GlcAT-I when manganese was added to the diet.

Reference

Xiao J.F., Y.N. Zhang, S.G. Wu, H.J. Zhang, H.Y. Yue and G.H. Qi. 2014.Manganese supplementation enhances the synthesis of glycosaminoglycan in eggshell membrane: A strategy to improve eggshell quality in laying hens. Poultry Science. 93(2):380-388. doi: 10.3382/ps.2013-03354