Processes of egg formation in poultry - SS1 Agriculture Lesson Note

The process of egg formation in poultry, also known as oogenesis, is a complex and highly regulated biological process. It involves several stages, from the development of the egg within the hen's ovaries to its eventual release as a mature egg. 

Source:(agric4profits.com)

 

Ovary Development:

The process begins with the development of the hen's ovaries. Hens typically have two ovaries, but only the left one is functional.

Within the ovary, there are thousands of tiny structures called follicles. Each follicle contains an immature ovum (egg).

 

Follicular Development:

In a continuous process, some of these follicles start to mature. The maturation process is regulated by hormones, with follicle-stimulating hormone (FSH) playing a significant role.

As the follicles mature, they increase in size and develop a yolk, which is the food reserve for the developing embryo.

 

Ovulation:

When a follicle reaches a certain size, it is released from the ovary in a process called ovulation. This mature follicle is now referred to as the ovum or egg yolk.

 

Magnum:

After ovulation, the egg yolk enters the oviduct, a long, convoluted tube where the egg white (albumen), membranes, and shell will be added.

In the first section of the oviduct, called the magnum, the egg white is secreted and gradually builds up around the yolk.

 

Isthmus:

The egg moves into the isthmus, where the inner and outer shell membranes are added. These membranes provide protection and support for the developing embryo.

 

Uterus or Shell Gland:

In the uterus, also known as the shell gland, the shell is formed. It consists of calcium carbonate and is gradually deposited around the egg.

The time the egg spends in the shell gland determines the thickness of the eggshell.

 

Isthmus and Shell Gland Contractions:

Contractions in the isthmus and shell gland help shape and size the egg. The shell's color is also determined during this phase, with brown or white eggshells depending on the breed.

 

Vagina:

The egg, now fully formed with shell and membranes, moves through the vagina. It may pick up some additional protective coatings during this phase.

 

Laying:

Finally, the egg is laid through the cloaca, the common opening for eggs, feces, and urine. The hen's muscles in the oviduct and cloaca help propel the egg out of the hen's body.

 

Incubation or Collection:

Once laid, the egg can either be collected for consumption or incubated to develop into a chick.

The entire process, from the initial formation of a follicle to the laying of an egg, takes about 24-26 hours. It's a remarkable example of the intricate biological processes that occur within poultry, ensuring the production of eggs for reproduction or human consumption. Proper nutrition and environmental conditions play a crucial role in supporting this process in commercial poultry farming.