الفهرس 
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Abstract
Although it represents no more than I 0% of the weight of egg, the
shell is a vital, and for everyone involved in producing, marketing and
conswning eggs, the most visible. Producers and marketers rely on the
eggshell to protect and contain the food contentes of the egg untill these
are used by the conswner. Everyone in this chain of production and
conswnption is interested in reducing the breaking of eggs. Egg breakage
lead to the wastage or at least downgrading of the entire egg contents.
According to Hunton (1995), losses of eggs worldwide due to
damaged shells exist despite recent advances in research, quality control,
and applied technology.
The losses sustained by the commercial egg industry, worledwide, are
difficult to estimate. Estimates of average of total eggs cracked or lost
prior to reaching their final destination have been shown to range from 13
to 20% (Roland,1988). According to the statistics of 1995 world hen egg
production reached about 740,000 million eggs (hatching eggs are included
in this figure). (Watt Poultry Statistical Yearbook, 1996). Thus the losses
sustained by the commercial egg industry amounted to form 96,200 to
148,000 million eggs, which, if priced at US 60c/dosen, would be worth$
4810-7 400 million in that year. The losses sustianed by Egyptian egg
industry on this basis reached about £.E 62.4 to 95.9 million in 1995 (total
egg production 2,822 million eggs).
One of the main factors leading to poor eggshell quality is insufficient
shell calcification due to premature oviposition.
Prostaglandins are involved in the oviposition of normal hard-~helled
eggs.