A good effort at your Wikipedia page Jess! You have included some good information and diagrams/pictures. Grade

B+=

Embryo Development:

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Day 1:
  • The brain crease begins to form.
  • The chicken's brain and nervous system start to form.
  • The chicken's head fold start to form.
  • The blood islands start to appear.
  • The eyes start to form.
birth_of_chicken_08
birth_of_chicken_08

Day 8:
  • Visible on the tail are three rows of feather germs
  • Inner eye lids start to form.
  • The egg teeth start to form.
    birth_of_chicken_12
    birth_of_chicken_12
Day 12
  • Scales begin to form on the lower legs.
  • The embryo is continuously moving and growing.
  • The ribs start to harden
Day 16
  • The embryo starts to turn its beak towards the egg's air cell.
birth_of_chicken_18
birth_of_chicken_18

Day 18-19
  • The beak breaks through the inner shell membrane
  • The lungs start to work.
  • The yolk sac starts to enter the body cavity.
birth_of_chicken_19
birth_of_chicken_19

Day 21:
  • The neck starts to spasm
  • The chick hatches

Egg Fertilisation:

In a hen the egg starts off with just the yolk which is formed in the ovary. Then when the yolk is realesed it enters the Infundibulum where the rooster's sperm is waiting. Then the egg is fertilized and goes though different parts of the oviduct to form the rest of the egg such as the shell membrane and the shell. Then the egg is released out of the chicken by going through the Cloaca. The amount of time it takes for a chicken to lay her eggs takes about 21-24 hours and a chicken will not lay her eggs if it's not the morning or early afternoon.
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Incubation:

An Incubator is what premature animals are put in when they are unable to have their mothers help. The Incubators keeps the infant warm. They are either set to stay a particular temperture or they are connected to a probe that monitors the babys tempreture so it can heat or cool the air as needed. The incubators also protect the infants from infection, noise and light. An Incubator helps with the development of a chicken embryo because an embryo cannot resume with cellular growth until the egg is the right environmental conditions. The conditions in an incubator are 38.61 degrees C. in a still-air incubator and 37.5 degrees C. in a forced air incubator. The humidity should be around 50 to 55% some say to raise the humidity in the last three days to 58%. These conditions are important because if the incubator is under-heated it can slow down the chicks growth process,but if the incubator is over-heated it can cause injury or death to the infant.
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Preparing eggs for sale:

Receival: First the refrigerated trucks deliever the eggs from the egg farms to the grading floors for testing the quality, grading and for packing. When the eggs arrive,trays of eggs are put on to trolleys and taken to large tempreature and humidity-controlled coolrooms. This will keep the eggs fresh until it is time for them to be packed. suction heads will pick up the eggs from their trays and place them on a conveyor belt. The eggs might be washed to remove any dirt or manure that may still be on the egg.
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Re-oiling: The cleaning process which is used removes the egg shells natural (bloom) that help to keep the eggs fresh. Some of the grading floors send the cleaned eggs into a re-oiling station so a micro-fine mist of oil can re-coat the washed egg.
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Quality testing:To make sure the consumers get the best value for money and have the best quality eggs, the eggs are tested for egg white height, yolk colour and shell thickness. When they arrive at the grading floors a sample from each batch of are taken to be tested. The sample eggs are broken and put onto level surface and the thick albumens hight is measured with a micrometer. The measurement is cheaked against the weight of the egg to give a haugh unit measurement. Eggs that have a low haugh unit will have runny whites and they may be rejected. The yolk is also checked to see the size, shape, colour and defects.The random yolk testing will ensure that the yolks colour is of an acceptable standard. Most consumers will perfer a bright yellow yolk.
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Candling: All the eggs that remain on the conveyer belt pass over a very strong light which will allow the operator to see the inside of the egg and look for any internal defects like blood spots, and any shell defects like cracks or dirt spots. This process is called Candling. Some grading floors will use electronic crack detection. If any defects are found the egg is removed and put into processed egg products.
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Stamping:
Some of the grading floors and packing floors will stamp the eggs with a special code that has the eggs farm of origin and the day that egg was processed. This process will help if the grading floor needs to find the eggs farm of origin.
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Grading:Eggs are weighed mechanically and are sorted into different sizes which are called grades and then the eggs are packed. The grade sizes will vary between different egg marketers. There are between three and five major egg grades generally available to the consumers. On an egg carton the weights marked are the minimum weights.
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Packing:Next the graded eggs are put into egg cartons and the 'best before' or 'used by date' is added to the cartons. Then the cartons are taken by a conveyor belt to the packing area. At the packing area the egg cartons are put into boxes and onto pallets for transport to the storage area. The packed eggs are kept cool in storage areas (the tempreture is about 15 degrees C) before they are taken to the different retail outlets.

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Layer Chicken Breeds:

Leghorn:
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A Leghorn chicken lays white eggs, the eggs they lay are larger than other chicken eggs. Leghorn chickens are one of the most used chicken layers for the egg size they produce.

Production Red:
external image production_red_hen.jpg
A production red chicken lays brown eggs and the number of eggs they lay per year are 250-300 eggs.

Austra White:
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An Austra Whites eggs are white but tinted and they produce 250 eggs or more per year.