Egg Formation and Embryonic Development: An Overview

Egg is a reproductive body laid by female bird. Chicken egg is oval in shape and mainly consists of shell (outer hard cover), albumen (white part of egg) and yolk (yellow part of egg). Generally, eggs are used for human consumption (i.e. table egg) and chick production (i.e. hatching egg). The biological value of egg is very high, 93.7 out of 100, which indicates the presence of different essential amino acids in the chicken egg are in proper amount and proportion. Egg is formed gradually in the different parts of female reproductive system of hen such as ovary, infundibulum, magnum, isthmus, uterus (known as shell gland) and vagina which takes about 24 h. There are different egg-producing chicken breeds in the world such as Leghorn, Ancona, Minorca, Blue Andalusian and Fayoumi. In this chapter, we discussed about structure of a chicken egg, nutritive values, how an egg is formed in reproductive tract of hen, egg-producing chicken breeds, layer strains, broiler strains, egg fertilization and embryo development of chicken egg.