Na

7,700

Note: All values in millions of eggs.

"Includes East and West Germany.

'Includes only Russia and Ukraine of former USSR.

Source: Ref. 1 (1967,1977,1987,1997).

Note: All values in millions of eggs.

"Includes East and West Germany.

'Includes only Russia and Ukraine of former USSR.

Source: Ref. 1 (1967,1977,1987,1997).

White (albumen)

Outer thin Firm or thick Inner thin Chalaziferous Chalazae

Membrane Air cell

Outer shell membrane Inner shell membrane

Shell

Cuticle Spongy (calcareous) layer Mammillary layer

Yolk (ovum)

Germinal disc (blasdoderm) Latebra

Light yolk layer Dark yolk layer Yolk (vitelline) membrane

Membrane Air cell

Outer shell membrane Inner shell membrane

Figure 1. A schematic of the parts of an egg. Source: Ref. 4.

so that the matured yolk can be dropped into the infundib-ulum of the oviduct without the rupture of any blood vessels in the follicular membrane. A blood spot in an egg is generally caused by incomplete formation of the suture line.

The oviduct consists of five identifiable sections: infun-dibulum, magnum, isthmus, uterus, and vagina. The in-fundibulum, or funnel, collects the yolk, or ovum, and by peristaltic action moves it on to the magnum region, where the thick albumen is secreted and laid down in layers on the yolk. In the isthmus the shell membranes are formed around the yolk and thick albumen. The membranes, two in number, only loosely fit the enclosed material. Most of the time that the egg is in the oviduct is spent in the uterine section where thin albumen fills the shell membrane sack and the shell is laid down to form the rigid egg protective layer. The shell color is determined by the breed of the hen. Generally, hens with red earlobes produce brown-shelled eggs, and white-shelled egg producers have white earlobes. The total time spent in the oviduct is usually about 24 hs. Total time for the formation of the egg from the start of rapid growth of the ovule to time of laying varies from 12 to 15 days.

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