Some factors affecting the incidence of cracks in hens’ egg shells

The hen's egg: Relationships of seven characteristics of the strain of hen to the incidence of cracks and other shell defects

“…It is not supported by data on shell thickness, since brown shells, on average, are either of the same thickness as white ones (Anderson et al, 1970a) or thinner (Hutt, 1949;Overfield, 1970). Another widely held belief is that the best way to achieve a low incidence of shell cracks is to ensure that the eggs produced have thick shells.…”

“…Another widely held belief is that the best way to achieve a low incidence of shell cracks is to ensure that the eggs produced have thick shells. However, though there clearly is some relationship between crack incidence and shell thickness (Tyler and Geake, 1958, i960;Bowman and Challender, 1963;Wells, 1967a, b), when flocks of different strains are compared the proportion of the variance of crack incidence attributable to variation in shell thickness is usually small and may be non-existent (Leech and Knowles, 1969;Anderson et al, 1970a). Biological factors other than shell thickness with a known effect on crack incidence include egg weight, rate of egg production and the height through which the hen drops the egg at oviposition (Tyler and Geake, 1958;Carter, 1971a).…”

Eggshell strength: A relationship between the mechanism of failure and the ultrastructural organisation of the mammillary layer

“…Although the majority of cracked eggs arise as a result of insult, as one egg collides with another egg or part of the collecting machinery (Anderson et al, 1970;Hamilton et al, 1979), it is the evaluation and improvement of shell strength which has posed the more difficult problem. On average between 6 and 8% of all eggs produced in the United Kingdom are downgraded annually.…”