To our knowledge, there are few reports of dietary
manganese effects on the ultrastructure and mechanical
properties of eggshells. Manganese is a component
of Galβ1,3-glucuronosyltransferase (GlcAT-I), which
catalyzes the transfer of a glucuronic acid residue onto
the nonreducing end of the second galactose of the proteoglycan
(PG) trisaccharide primer Gal-β1,3-gal-β1,4-
Xyl-β1-O-Ser (Ouzzine et al., 2000).