The measurement of egg shell strength: A comparison of four methods

Abstract

A variety of methods exists for assessing egg shell strength. For practical field use, a method is desired which is relatively rapid, easy to use and cheap. It must demonstrate differences between experimental varieties or nutritional treatments with sufficient precision that decision makers can rely on the results. A study has been made of eggs from 10 inbred lines of White Leghorns using non‐destructive deformation, beta backscatter count, deformation at failure, force at failure, shell stiffness and shell thickness to estimate shell strength. A comparison of these methods indicated that under the conditions of this experiment, backscatter count yielded low coefficients of variation and did not demonstrate differences between inbred lines. The other methods showed differences between lines with non‐destructive deformation possessing an acceptable combination of precision, ease of operation and cost. Deformation and force at failure and egg shell stiffness required expensive non‐portable apparatus but stiffness was nevertheless thought to be a useful parameter. Direct measurement of shell thickness was acceptable but necessitated breaking the eggs.