The hexosamine and uronic acid contents of the matrix of shells of eggs from pullets fed on diets of different manganese content

Synopsis

Three experiments are reported concerning the effect of the manganese content of the diet on the acid mucopolysaccharide content of egg shell matrix. In the first experiment hexosamine was taken as an index of acid mucopolysaccharide, but in experiments 2 and 3 uronic acid was determined instead.

It was found that a low‐Mn diet depressed the hexosamine and uronic acid content of the matrix of eggs sampled at the start of lay. However, eggs from low‐Mn fed pullets after three months of lay showed a significant increase in matrix uronic acid.

Other characteristics of shells from low‐Mn fed pullets taken at the start of lay were a low weight of shell per unit area and a high weight of matrix per unit area, which led to an abnormally high proportion of matrix to mineral in the shell.

As a model for normal shell development eggs were extracted from the uterus at an early and late stage of shell formation. Although these uterine shells resembled the poor shells from the low‐Mn diet from the point of view of poor shell thickness and low matrix uronic acid content, the proportion of matrix to mineral in shell was similar to that of the fully‐formed shells and not as high as in shells from low‐Mn fed birds. This last observation led to the conclusion that low‐Mn shells were not unfinished products arising from a premature expulsion from the oviduct.