Preservation of eggshell quality pre and post lay

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Biological contamination

Biological contamination of egg contents (yolk and albumen) by microbes is hugely affected by the capacity of the eggshell to prevent or inhibit entry, invasion and infection, mainly by bacteria but also fungi and viruses, via the many microscopic pores that perforate the eggshell. Provided the cuticle or bloom deposited by the hen on the shell is sufficient in quality and coverage it will act as effective additional barrier to ingression by microbes.

Egg washing makes eggs look nice and clean for the consumer but also removes most if not all of the cuticle or bloom from the surface of the eggshell. Egg washing clearly makes for the easier entry of microbes by destroying the integrity of the cuticle or bloom but the pair of inner shell membranes will play a significant role in preventing the entry of bacteria into washed eggs.

Many management factors combine to ensure conservation of eggshell quality. Providing the poultry farmer manages his/her flock in the correct and proper manner, through provision of the right nutrition and house conditions, then high egg shell quality should come automatically.

Management tips

Useful tips to assure production of eggs having consistently good eggshell quality include house conditions free of stress and to strictly avoid scaring laying birds. This will ensure that the egg spends the required amount of time in the shell gland to provide adequate shell thickness, strength and integrity. 

Research and experience shows adoption and use of an 'ahemeral' lighting programme (cyclical with a period not equal to 24 hours) is highly effective in making sure that hens retain their eggs for a longer time in the uterus to produce the required shell thickness. Nutrition is another key factor with properly formulated feed rations with optimal amounts and concentrations of calcium and phosphorous, generally regarded as 3.50 to 3.75 per cent calcium and 0.45 per cent phosphorus.

All other things being equal (e.g. correct photoperiod and feed rations) young layer flocks will always produce eggs with thicker and stronger shells. This means farmers should expect a higher incidence of thinner shells and correspondingly higher shell breakage with older flocks and those laying eggs several months after moulting.

Monitoring and managing flock health is also important in respect of eggshell quality because diseases such as infectious bronchitis and Newcastle disease are responsible for eggshell abnormalities with respect to shape and texture.

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