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Star cracks


Star cracks are fine cracks radiating outwards from a central point of impact, which is often slightly indented.

The egg in the photograph has been placed over a bright light. This is the way it would look to a candling operator.


The incidence varies with flock age but is usually 1 to 2% of total production.

Cause Control
Reduced shell strength due to:
Ageing Keep flock age as low as economically possible.
Poor nutrition Make sure that the birds’ nutrient intake is correct (particularly regarding calcium and vitamin D3) Mixed feed should be handled carefully so that the different components do not separate out. This particularly needs to be checked when augers and automatic feeding systems are used.
Saline water Desalinate, dilute or do not use drinking water
containing problem levels of salts.
Diseases such as infectious bronchitis Follow an effective vaccination programme.
High shed temperatures Control temperatures by using foggers, fans, roof
sprinklers, white roofs, insulation and good ventilation.
Mechanical damage caused by birds’ beaks and toenails Make sure that:
• the cage floor is not too rigid.
• the slope of the floor is just enough to allow eggs to
roll out.
• roll-out trays cushion the eggs as they come to rest
against the edge of the tray.
Infrequent egg collection Collect eggs at least twice a day.
Rough handling Do not collect eggs in wire baskets. Reduce the severity
of impacts during mechanical handling by:
• cushioning metal egg guides.
• keeping egg roll-out angles between 7 and 8°.
• minimising the number of rows of eggs being fed
onto cross-conveyor belts at any one time.
Educate staff to handle eggs with care during collection
and packing.
© The State of Queensland, Australia (through its Department of Primary Industries and Fisheries) and DSM Nutritional Products Ltd., 2007. No part of this publication may be reproduced, copied or transmitted save with prior written permission of Director, Intellectual Property Commercialisation Unit, Department of Primary Industries and Fisheries, GPO Box 46 Brisbane, Queensland, Australia 4001, and DSM Nutritional Products Ltd.
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