STUDIES ON THE ULTRASTRUCTURE OF CHICKEN , EGGSHELL AND ROLE OF PROSTAGLANDIN IN DETERMINING IT'S QUALITY

Abstract

Although it represents no more than 10% of the weight of egg, the shell is a vital, and for everyone involved in producing, marketing and consuming 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 consumer. Everyone in this chain of production and consumption 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 fucluded 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$

4810-7400 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-shelled eggs. Plasma concentration of prostaglandin increases immediately before and during oviposition and then decreases following expulsion of the egg