These observations may provide a basis for a non-invasive method of assessing stress in laying hens as well as helping to account for hitherto inexplicable occurrences of declining egg shell quality. Dusted or pink eggs followed moderate retention whereas white banded eggs were seen after prolonged retention. Disturbances when eggs were only lightly calcified tended to result in misshapen eggs, while those occurring when oviposition was imminent tended to result in coated eggs. There was evidence that the nature of the particular abnormality produced was dependent on the stage of egg formation at which the disturbance was imposed and, if retention followed, upon the length of time the egg was retained. Administration of 0.1, 0.25 or 1.0 mg of adrenaline subcutaneously resulted in the retention of eggs currently in the hens' shell glands and in an increased proportion of eggs with abnormal egg shells being laid during the following 10 d. Exclusion from their nests of birds accustomed to laying in nest boxes resulted in disturbed prelaying behaviour, retention of eggs in the shell gland and an increased proportion of coated eggs. Disturbance to flocks on deep litter resulted in an increase in the proportion of eggs laid with abnormal shells on the following day, not only in the flocks directly affected but also in an adjacent flock. Translocation of hens from pens to cages resulted in a decrease in egg production and an increase in the proportion of abnormal eggs over the succeeding 18 d. B quality grade for egg shape will include eggs that are clearly misshapen or that have definite flat areas. The abnormalities fell into two main classes: misshapen or bulging eggs and eggs coated with a superficial layer of amorphous calcium, variously termed dusted, white banded, chalky or pink eggs. Concern regarding the proportion of brown eggs being laid with abnormal egg shells led to an investigation of the relationship between disturbance or stress and egg shell appearance and quality.
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