School Science Lessons
Agriculture
2025-11-04

Chicken Project 1

Contents
5.0 Broilers, Chicken meat production
7.0 Care for young chickens
6.0 Chicken anatomy
9.0 Chicken eggs
2.0 Chicken feed
3.0 Chicken house
3.1 Chicken drinker
1.0 Chicken project management
4.0 Deep litter
8.0 Layers
10.0 Chicken diseases
17.0 Chicken egg
11.0 Chicken hatching
16.0 Keeping chickens at home
15.0 Killing chickens
12.0 Prepare chickens for food
13.0 Prepare eggs for food
14.0 Profits, costs, returns
9.0 Chicken eggs
9.1 Egg laying, onset, clutches, cycle
9.2 Egg preservation
9.3 Egg production
9.4 Egg structure
9.5 Egg yolk
9.6 Egg white
9.7 Tests for egg age and grading
9.8 Egg experiments
8.0 Layers
8.1 Cages for layers
8.2 How long to keep layers
8.3 Housing layers
8.4 Layers, Point of lay.
8.5 Laying hens
8.6 Management and feeding of laying hens
8.7 Modern egg-laying chickens
8.8 Nests for layers
13.4 Roosters
8.10 Timing of replacement stock
7.0 Care for young chickens
7.1 When the chickens arrive from a hatchery
7.2 Caring for young chickens
7.5 Chicken brooders
7.4 Feeding young chickens
7.5 House for young chickens
6.0 Chicken anatomy
6.1 Digestive organs
6.2 Post-mortem dissection
63 Reproductive organs
1.0 Chicken project management
The systems of management of chicken projects
1.1 Backyard chickens
1.2 Village system
1.3 Semi-commercial system
1.4 Commercial system
1.5 Daily management
1.1 Backyard chickens
In Australia, people keep about 10 chickens (called "chooks"), in their backyard to provide fresh eggs and manure for the compost bin.
Also some growers of citrus fruit use chickens to eat weeds and grass under the trees and fertilize the trees.
The chickens are fed on kitchen waste, plate leftovers, and a variety of grains, cracked wheat, pellets or mash.
Some people add raspberry juice and a coccidiostat to the drinking water.
Before delivery of chickens from the breeder the chicken house must be ready, equipped with feeders, waterers, laying boxes and a roost.
Also, the chickens will need fresh water every day in summer and every two days in winter and an area for free range feeding from the age of 20 to 22 weeks.
The chicken house must not allow the entry of predators, e.g. pythons and other snakes, dogs, cats, foxes.
Docile breeds, e.g. Rhode Island Red or bantams are more suitable for backyards than commercial breeds.
1.2 Village system
In this system the chickens are allowed to run all over the village.
They are sometimes fed bought feed, but usually scavenge for themselves and they hatch their own eggs.
In other words, the chickens are just "there" and the owner takes the eggs and meat for his table whenever he wants and whenever they are available.
In this system production is usually very low, mortality rates are very high and it is a very inefficient method of keeping poultry.
However, the advantages are that the owner does not have to spend any time or money on the chickens, and can devote his time to other things that may be more important to him.
We must carefully study any methods to improve the efficiency of this type of poultry, keeping bearing in mind the owner's desires and the availability of time and money.
1. Village chicken project
Many people like village chickens, because they do not appear to need any care.
The chickens find their own food and look after themselves.
They hatch out clutches of chickens and some of these chickens grow up into adult birds.
In some villages, chickens can always be found to be killed and eaten.
2. Chickens
When a hen goes broody, it should hatch many chickens and nearly all chickens should live and grow to a big size.
However, in some villages many chickens do not survive.
A village hen may hatch out 10 or more chickens from her eggs.
She then walks about the village with young chickens following her.
However, after about 3 weeks she may have only a few chickens left, because the other chickens have died.
In some villages most of the hens are not laying eggs.
Some have stopped laying and spend all day sitting on their eggs so they will hatch out.
Chicken production would increase if most hens were laying eggs, and only a few hens were going broody and sitting on eggs to hatch out chickens.
Some have hatched their chickens and spend all day walking around the village trying to find food.
They are not laying eggs at this time.
3. Activity: Investigate what happens to little chickens when the hen takes them to find food in the village.
Tie labels on the legs of the chickens, e.g. label A for a particular hen and labels A1, A2, A3 . . . for her young chickens.
Note how many village hens are broody and sitting on eggs or broody with young chickens.
Note how many village hens are not broody.
To check whether these hens are laying eggs, catch the hen and observe whether the lay bones are two fingers apart, and the vent (cloaca), is soft
and moist.
When holding a hen, lock their wings between your arm and your body so they feel enclosed.
4. Hens
Village hens have not been bred to lay eggs.
They are descended from chickens that have always lived in the village.
These chickens do not lay many eggs and do not produce much meat.
They are small chickens compared with modern chickens bred to lay many eggs or produce much meat.
All domestic breeds of poultry were bred, starting about 8 000 years ago from the south-east Asian red jungle fowl (Gallus gallus).
It produced eggs about half the size of modern poultry, but were more active and exploratory, and more likely to try new foods and avoid predators.
Modern egg breeds can produce many eggs, but they are expensive, need special imported food and require much work to look after them properly.
The hens of fast growing big meat chickens will not lay many eggs.
Chickens that lay many eggs will have small bodies and not much meat on them.
So breed chickens for egg laying or for growing meat, but not both purposes.
5. Hen with chickens
Put a hen with her chickens in a small yard with a creep in it to investigate how small chickens can be saved from dying.
5.1 Find a hen that has just started to sit on her eggs.
Count the 21 days and be ready to find the hen when she has hatched out her chickens.
Then drive the hen and chickens into the house made for them.
5.2 Find a hen that is walking around the village with many new chickens.
Drive the hen and her chickens into the house made for them.
6. Chicken feed
Decide what food to give the little chickens.
Imported special food for little chickens called "chicken starter" may be too expensive for a village chicken project.
6.1 Energy food: Make energy food from grated coconuts or from root crops cooked and grated into small pieces.
6.2 Protein food: Make protein food from small fish, scaled, boiled until cooked and scraped into small pieces.
Also, use small crabs and shellfish and big African snails.
Soft legume plants, e.g. each pea, can be chopped up into small pieces and mixed with other food.
6.3 Vitamins: Some soft green feed should also be cut into fine pieces and mixed with the food.
6.4. Minerals: Get some mineral mixture from an agriculture extension officer and mix the food or mix in a little salt and a little clean soil.
7. Chicken medicine
Ask an agriculture extension officer about using a medicine to prevent disease coccidiosis, e.g. drugs such as Amprolium, Sulfaquinoxiline, or Sulfamezathine.
They may be very expensive.
Use them for the first 5 weeks of the chickens' life.
8. Chicken house
When the chickens arrive, put prepared food in the creep.
Provide food for the hen and the small chickens.
Keep the small chickens in the house or open the house only in the afternoon, to allow the hen to take the chickens outside to find some food.
The hen will teach the little chickens to find food, but the hen must take them back to the house before the night.
By the time the chickens are six weeks old, they are bigger and stronger and can look after themselves, so you can let them go out of the house.
9. Records
Keep records of the village chicken project:
* Number of chickens put in the project, n1
* Number of chickens were still alive at six weeks of age, n2
* Calculate percentage survival (n2 / n1) × 100
* List causes of death: disease, eaten by dogs, trodden on by humans, lost in the village, drowned
* List kinds of energy food and protein food given to chickens.
10. Layers
Growing village chickens as layers
The cockerels can be killed and eaten or sold in a market.
Get more eggs from the village pullets by giving the chickens some food in the house, to get them used to coming to the chicken house.
When the chickens grow bigger, build a bigger creep.
Build some nests in the house when the pullets approach 20 weeks of age.
They will see these nests when they come to the house to find food.
Later when they start laying as hens they will not have to go searching for the nests and collecting the eggs will be easy.
If some eggs are left in the nest, the hens keep laying and stop them from going broody.
Keep some cockerels with the pullets to have fertile eggs.
Modern chickens must be kept shut up in their own separate house so that they will not steal the food from the village chickens, and not mix with the village chickens and catch diseases from them.
11. Activity: Investigate the habits of village hens
* Note where the chickens lay eggs and how many days after laying before the chickens hatch (usually 21 days).
* Note the number of hens and roosters in the village.
* Note the colours of the hens and roosters.
* Note how many hens have very small chickens and larger chickens.
* Note how many older chickens the hens have.
Find a nest where a hen is sitting on some eggs.
* Note how long the hen stays sitting on the eggs before she gets up to move around.
* Note whether the hen has shelter from the rain, protection from other animals, e.g. dogs.
* Note how many eggs the village hens lay.
* Watch a hen walking with her chickens.
* Note how often the chickens eat something.
* Note whether the chickens stay near the hen.
12. Cause of death
Investigate why some chickens die, e.g. run over or squashed, eaten by cats or dogs, drowning, starvation, disease.
13. Danger sounds
Note the noise the hen makes to call the chickens or when danger is nearby.
Note what happens when a hen sees a hawk nearby.
1.3 Semi-commercial system
A semi-commercial system can achieve an increase in production over traditional village farming, if housing and supplementary feeding is available.
This system requires the chickens to be kept in a house, where they are given their supplementary feed and where they will lay their eggs, until about midday.
At midday they are let out to scavenge as they would in the village system.
In this system the farmer grows either some special feed for the chickens or purchases feed.
This farmer will probably have bought some chickens from a hatchery.
They will probably be better quality than village poultry and have the capacity to produce more eggs or meat.
With this system the farmer is trying to produce more eggs and meat and sell any surplus, to pay for bought feed and the cost of the bought chickens.
The farmer may use this system of poultry keeping to provide protein for the family.
1.4 Commercial system
This is the keeping of poultry for business purposes.
Most of the eggs and meat are sold by the farmer.
This system of poultry keeping usually fails if the farmer does not have the knowledge or management ability to make a profit.
1.5 Daily management
1. Feed and water the birds.
2. In the afternoon, clean both the feed and water troughs.
3. Collect the eggs.
4. Let the chickens out at 12 o'clock.
5. Lock the chickens up at night.
Twice a week:
6. Rake over the deep litter and replace any wet litter.
7. Clean out nests and put in fresh nesting material.
Yearly:
1. Thoroughly clean out the house.
2. Take out the deep litter and use on a vegetable garden.
3. Put in fresh litter.
4. Sell the old chickens and replace with young chickens that have been either bought or reared in the village.
Cull by selling or eating the laying stock at 18 months of age, i.e. after they have been laying eggs for 12 months.
If chickens are kept longer than 18 months, it will cost more to feed them than the money the owner receives from the sale of eggs.
Time the replacement of his laying stock so that they will start laying eggs at the time that the layers have reached 18 months.
To be ready at the right time, the replacement stock must be bought as day old chickens when the laying stock is 12 months old.
5. Make any necessary repairs to the house.
Commercial meat production
Use commercial poultry breeds, because of the high cost of food.
Get as many eggs as possible from the chickens by using good quality stock.
Hybrid chickens can only be used commercially to produce meat or eggs.
The eggs or chickens of commercial breeds must not be used for hatching or breeding.
So commercial breeds must be replaced as existing stock become old.
Hybrid stock is used for commercial poultry farming, because their production is much higher than the ordinary pure breeds, e.g. White Leghorn.
Care of growing chickens
1. Make sure there is enough dry litter on the floor for the chickens to walk on.
There should be no smell, because the dry litter will absorb the moisture in the wet droppings.
2. Make sure chickens have enough to eat.
Start to use a bigger kind of feeder hung from the rafters and is raised as the chickens grow.
It should be raised so that the top edge of the feeding tray is the same level as the shoulder of the chickens.
For older chickens feeders should be set level with their shoulder height.
This feeder can be made from an oil drum that has been washed out or a box.
3. Make sure the chickens have enough water to drink with a coccidiostat added to it.
The 5 things needed in a good chicken house are dry, cool, safe, perches, enough space.
The sign of coccidiosis disease is blood in the droppings.
Twelve laying chickens need 4.4 m2.
Never use iron or plastic sheeting when making a chicken house.
2.0 Chicken feed
When the chickens are out scavenging in the afternoon, they will find some feed.
However, most of it will be of a carbohydrate nature that is low in protein and unless they are fed a high supplement their production will be low.
Purchase either a high protein feed, e.g. protein concentrate and meat meal, or grow a high protein feed, e.g. soybeans.
Buying high protein feed is easier, but it may be expensive.
Mix the high protein feed with cooked sweet potato, taro, yams, or grain, e.g. sorghum or corn, in equal proportions, so that each chicken receives
56 g of feed per day, i.e. 28 g of high protein feed and 28 g of other feed.
Fed in this way, a 50 kg bag of high protein feed would last eleven chickens more than 5 months.
The sale of one egg per day from the project might cover the cost of the bought feed.
Using this type of feeding expect about three eggs per day from ten hens.
If growing feed, estimate how much feed you need to grow.
An adult chicken will eat 110 g of feed per day, and although the chickens will be outside scavenging for 4-5 hours per day, still provide this amount of feed.
At 110 g of feed per day the eleven chickens will eat 1.25 kg feed per day, i.e. 8.75 kg per week or 455 kg per year.
Below are some suitable mixed rations for this system, provided the chickens can run outside for 4-5 hours every day:
1. Crushed grain 64, Dried green feed 5, Peanuts 21, Concentrate 10, Total 100 kg
2. Crushed grain 79, Dried green feed 10, Concentrate 11, Total 100 kg
3. Crushed grain 60, Crushed peanuts 40, Total 100 kg
4. Crushed grain 70, Crushed soybean 30, Total 100 kg
Cook soybeans and peanuts for twenty minutes and then dry them before mixing into the ration.
To produce a heavier carcass before killing for meat, give extra rations, e.g. fresh meat offcuts, skim milk, softened grain, but not barley.
Free range chickens have lighter carcasses than restricted range chickens.
Limiting range of movement produces a heavier carcass, but the chicken must not become stressed by space restriction.
3.0 Chicken house
See diagram 50.6.3.7: Construct a chicken house
See diagram 50.6.3.8: Broiler house
See diagram 50.6.3.9: Door end of house
The house needs have only 0.25 m2 per bird.
It should be made out of bush materials.
For 10 hens and one rooster, the house would be 1.5m × 1.5 m, have three nests, roosting space and a feed trough, and a water trough made with bush materials, e.g. bamboo.
The house should have a big roof overhang and a deep drain around the building to stop water getting in.
Cover the floor with deep litter material, e.g. chopped dry grass, coffee skins, rice husks.
3.1 Water reservoir for chicken drinker
See diagram 50.6.3.3: Brooder drinker
Use a flat dish that chickens can drink from.
Fill the dish with water.
Use a large bottle filled with water.
Close the bottle tightly.
Hang the bottle with a thread, mouth down and immerse under the water level in the dish.
Then remove the cover of the bottle under the water.
The water level in the bottle does not drop, because the atmospheric pressure on the water surface of the dish holds up the water.
If chickens drink some water and the water level in the dish falls below the mouth of the bottle, water in the bottle can drop automatically and the water level in the dish goes up again.
When water level in the dish rises to the mouth of the bottle, water in the dish stops falling automatically again.
49.0 Deep litter
Deep litter is any dry material such as coffee mill hulls, rice hulls, peanut hulls, sawdust, dry leaves, wood shavings, finely chopped dry grass.
When it is placed on the poultry house floor, it combines with the birds' droppings and undergoes a bacterial process, which gives sanitary non-smelling conditions when handled correctly.
This may sound like a lot of work for the project owner, however, very little work is required to look after it properly.
There are three things that have to be remembered:
1. The shed must be kept dry.
The roof must be rain proof and the overhang of the roof must be enough to keep the rain from blowing in.
Drinking water must not spill onto the litter.
2. The shed must not be overcrowded.
Note the floor space needs for various ages of stock.
If overcrowded, litter becomes hard and disease could be introduced to the house.
3. Turn the litter once a week and rake over to stop it going hard and to mix the birds' droppings evenly.
Advantages of deep Litter
1. Chickens burrow into the litter and cool themselves as the litter maintains a uniform below air temperature in hot weather.
2. Chickens burrow into the litter and warm themselves as the uniform litter temperature is above air temperature in cold weather and the litter acts as an insulation against the cold.
3. Chickens scratch in the litter, which gives them something to do and so stops feather picking, egg eating, and gives them a "dust bath", which controls lice.
Deep litter also provides some vitamin B12.
The droppings combine with the litter and bacterial action ensures that no smell develops and no flies breed in the dry deep litter.
Deep litter is a valuable fertilizer.
One 3 m X 3m house with 25 hens will produce in one year 3/4 tonne of deep litter fertilizer.
It is the equivalent of 112 kg ammonium sulfate, 100 kg superphosphate, 35 kg potassium, 5 kg magnesium, 5 kg sodium, 20 kg calcium, + trace elements.
It is a valuable by-product of the poultry project.
5.0 Broilers, Chicken meat production
See diagram 50.6.3.8: Plan of house for broiler production
Most poultry meat production will be for the "live" market and will be sold through the village market.
Meat chickens reach a marketable weight at 9-10 weeks.
To increase profitability, sell all the chickens at the same time.
So raise only the number of chickens that can be sold at the same time, e.g. 25-30 chickens.
If you keep the chickens longer than 10 weeks, it could cost more to feed them than the extra money received from their sale.
Broiler housing
A chicken needs a floor area of 0.1 m2.
Build the house with bush materials with a large roof overhang and surrounded by a deep drain to keep out any water.
Throw the earth from the drain inside the house and compact it until it is very hard.
This action raises the level of the floor to ensure that no water comes inside.
Cover the floor with 15 cm of deep litter material.
Put feed and water troughs in the house to allow 56 cm of feeding space per ten chickens and 28 cm of watering trough per ten birds.
Broiler management
Use only meat strain chickens for meat production, because they can produce more meat for how much feed eaten.
If you buy unsexed chickens, you can raise both pullets and cockerels for meat production.
Buy the chickens as day old chickens.
Broilers must grow as much meat as possible in as short a time as possible.
Feeding broilers differs from feeding pullets, because broilers must be fed a high protein diet for the nine weeks it takes to raise them.
Feed broilers a 20% protein medicated feed, which has to be bought.
Feed and water must be always available and must never run out.
If their growth rate becomes slower, the result will be less profit for the farmer.
After keeping broilers on this feed for the whole period, sell them when they reach 1.6 kg live weight.
Some broiler chickens will grow faster and may be sold in the eighth week, but all broiler chickens must be sold by the tenth week.
After ten weeks, the cost of feed may be greater than the selling price of the broiler chicken!
Daily management
1. Fill feed and water troughs three times a day.
2. Clean water troughs daily.
3. Rake over deep litter daily.
After each batch of chickens
1. Remove all deep litter and put on to a vegetable garden.
2. Thoroughly clean all feed and water troughs.
3. Rest the house for three weeks between batches of chickens.
6.1 Digestive organs
See diagram 50.6.5: Digestive organs and trachea
See diagram 50.6.6: Respiratory organs
1. The mouth has no teeth, only a strong beak that can pick up the food.
A short tongue has spines on it pointing backwards.
These help to push the food down the food tube.
2. The oesophagus is a long tube that has muscles in its walls.
The muscles help to push the food down this tube.
3. The crop is a part of the oesophagus at the bottom of the neck.
It is a place where food can be stored while the chicken eats quickly.
The walls of the crop can get bigger if much food is stored.
Hard pieces of food, e.g. big seeds, are stored in the crop.
Here they are softened.
4. The stomach is not very big.
When food comes into the stomach, it is mixed with digestive juices that come from the walls of the stomach.
These juices help to digest the food and turn it into a liquid that can be taken into the body.
5. The gizzard has very strong muscles in its walls.
When these muscles work, they squeeze the food and make it into small pieces.
Inside the gizzard is a rough hard lining and sand grains that the chicken has swallowed.
These sand grains and the rough wall help to grind up the food into small pieces.
The chicken needs a gizzard to grind up its food, because it has no teeth in the mouth.
The muscles of the gizzard contract strongly once every 30 seconds.
6. After the food leaves the gizzard, it goes into the first part of the intestine called the duodenum.
Here it is mixed with more digestive juices from the pancreas and the liver.
These juices help to soften and digest the food.
7. The intestine is a long narrow tube where digested food is absorbed into the blood to used by the body.
8. The blind gut has two tubes called caecae tied together and joined to the lower end of the intestine.
The food inside the caecae is liquid.
9. The large intestine is very short and contains the droppings.
10. The cloaca is the large opening at the end of the intestine.
11. Droppings are green with a capping of white uric acid and are semisolid.
The droppings from the blind gut are very soft and are only put out once a day.
To observe an animal's stomach, use food, chicken, scissors and knife, chloroform solution and lens.
The teacher has to recall the methods of studying internal organs of animals by means of dissection.
1. Digestion of food is in two stages:
1.1 Breakdown of food into smaller parts using teeth and tongue in the mouth.
1.2 Softening of the food by saliva in the mouth and acid in the stomach.
2. Let the students bite a dry biscuit.
Their teeth and tongue will break it into smaller pieces.
Soon it tastes sweet, because the saliva changes starch into sugar.
3. Kill a chicken and show the stomach.
It is like a bag made of hard muscle.
This muscle can mix the food with acid.
4. Cut open the stomach with scissors.
Turn the stomach inside out and show the digested contents.
5. Wash out the inside of the stomach and let the students examine it with a magnifier.
Can they see the folds in the walls?
Extra Activity: Show the inside of a cow's stomach called tripe.
You can buy this in a butcher's shop.
Compare the size with the stomach of a rat or rabbit.
6.2 Post-mortem dissection
See diagram 50.6.4: Chicken dissection
See diagram 50.6.0: External parts of a chicken
See diagram 50.6.4: Respiratory organs
Dissect a hen that has a red comb and is laying eggs.
Just before the lesson, kill the chicken by quick strangulation, but not in sight of the students who may be offended.
Pull off all the feathers then wash and dry them for later examination by the students.
At this stage do not cut the skin.
You will need a piece of wooden board, a hammer, 4 nails about 5 cm long, a new one-sided razor blade or scalpel, a pair of large straight cissors, string, old newspaper, scrap bucket.
1. Put the chicken onto the piece of board.
2. Study the marks where the feathers were joined to the skin.
In some places the skin is bare with no feathers.
3. Note the pin feathers on the skin.
Use a flame to burn off these feathers.
4. Lay the chicken on its back and nail it to the board.
5. Use the razor blade to cut through the skin over the breast bone and down over the thighs.
Follow the lines X-X in diagram 50.6.4.
See diagram 50.6.4: Chicken dissection
6. Pick up the edges of the skin and use the razor blade to cut away underneath the skin so you can lift it off the body.
Remove the skin from the whole area inside the dotted lines in diagram 50.6.4.
7. Put the flat palms of your hands on the legs and break the legs down flat.
Push down with your hands until the legs are alongside the body.
8. Make a deep cut with the razor blade through the breast muscle about 2 cm up from the base of the wing.
The lines A and B in the dissection diagram show where to make these cuts.
Cut down deep until you feel a bone, the main wing bone.
9. Use strong scissors to cut through the main wing bone.
Cut it on both sides, A and B.
10. Pull the covering of the abdomen out towards you a short distance and make a shallow cut in it, but do not cut the intestines below.
Continue this cut along the sides of the body towards the ribs, see the lines C and D in the dissection diagram.
11. Use strong scissors to cut through the middle part of the ribs where the two parts of each rib meet at an angle, and make a white mark under the skin.
12. Cut right around the sides towards the front of the bird.
Lift up the breastbone at the back and push it up.
Use the razor blade to cut the muscles holding it down.
Cut the breast bone and its muscles and remove it to reveal the organs of the body underneath.
13. Look in the neck for the windpipe.
It is white and has fine rings around it.
Follow it down to the chest where it joins the two bronchi.
Look for the narrow parts that make chicken sounds.
Cut off the air tube off and remove it.
14. Lift up the liver and cut underneath it so you can remove it.
Do not cut the green gall bladder.
Use scissors to remove the heart then mop up any blood left behind.
15. Look in the neck for the oesophagus.
Cut it near the head and tie string around the end.
Then follow the oesophagus to the crop that is very close to the skin, so cut it away carefully.
Follow the oesophagus down to the stomach and the gizzard.
Cut off the small red spleen that lies near the stomach.
16. Tie string around the end of the digestive tube near the cloaca to stop the droppings coming out.
Then cut this off between the string and the cloaca.
17. Lift all the digestive organs out of the body and put them on a piece of paper.
Pull the intestines aside so you can follow the tube for its full length.
18. Open the gizzard and observe its strong red muscles and the pieces of stone or sand in it that grind up the food.
Note the intestine, the two blind guts (caecae), and the short large intestine.
19. If the chicken is a male, observe the two large testes.
20. If the chicken is a hen, observe the oviduct.
Take out the oviduct and arrange it on a piece of paper.
Note the ovary close to the backbone.
Lift up the ovary and cut it away from the back.
Pull out the oviduct to see its parts.
6.3 Reproductive organs
See diagram 50.6.12: Male reproductive organs
See diagram 50.6.11: Female reproductive system
1. The male chicken is called a rooster or cock.
Inside his body are two pale yellow organs called testes, which make the semen.
The semen contains tiny sperm, which can swim to fertilize an egg by joining with it.
The fertilized egg can grow into a baby chicken.
Two small tubes coming from the testes take the sperms to the cloaca, where they stay until the rooster mates with a hen.
2. The female chicken, the hen, has an ovary, which makes eggs.
An egg is called an ovum (plural: ova) and it later becomes the yellow part of an egg, the yolk.
In the ovary the ova grow bigger until one of them is big enough.
It breaks out of the ovary and goes into a funnel at the end of a long tube, the oviduct.
In a narrow part of the oviduct the sperms are waiting.
3. After copulation, one sperm may join with the egg to fertilize it to allow the development of a chicken.
In the same part of the oviduct two cords, chalaza, are tied onto the yolk.
4. The fertilized egg then passes down to where the oviduct has thick walls.
Here the white of the egg, the albumen, is put around the yolk.
5. The fertilized the egg then passes down a narrow part of the oviduct, where two thin skins are formed around the egg.
The egg then passes into the shell gland, a tube with thick walls, where the hard shell is formed around the egg.
When the egg is laid, the hen usually sits on it and to keep it warm.
Then a chicken may grow inside the egg.
Teach this lesson during a post-mortem on a hen.
After taking out the digestive tubes, take out and the ovary and oviduct and lay them in a straight line on a piece of paper.
1. Take out the reproductive organs and lay them out in a straight line drawn on a piece of paper.
2. The ovary where eggs are made is attached closely to the back bone of the abdomen.
Use scissors to cut away the ovary to take it out of the body.
3. The yolks have many different sizes.
Some are very small.
As the yolks grow larger they are inside a sac covered with small blood vessels to bring food to the yolk to make it grow.
At the long space without blood vessels the yolk breaks out of its sac and starts to become an egg.
4. When a yolk in the ovary is big enough, it breaks out of its sac and it goes into a thin funnel, that leads down into a long tube, the oviduct.
The egg goes first through a very narrow part of the oviduct where, inside the egg, two cords are tied onto each side of the yolk.
If a rooster has mated with the hen, sperms will be waiting in this part of the oviduct to fertilize the egg.
Later the fertilized egg develops into a chicken.
5. The yolk then passes for 3 hours down a long part of the oviduct tube where the walls are thick to get a thick coating of white of egg.
Cut open the thick wall with scissors.
The egg then passes through an arrow part of the oviduct for 2 hours where 2 egg skins or egg membranes are added.
The egg passes into a part of the oviduct called the shell gland where it stays for about 20 hours while the hard shell is formed around it.
Cut open the shell gland.
If an egg is in the shell gland, take it out to dry.
The egg is dull, because it does not yet have a "bloom" on it.
The egg then passes through a short narrow part of the oviduct called the vagina, where the shell of the egg is covered with a sticky substance.
Later it dries and makes the shell look shiny, the "bloom" on the egg.
The bloom helps to keep out bacteria that might attack the egg and make it go bad.
6. Double yolk eggs are larger than the eggs laid by the other hens in the flock.
Double yolk eggs are often sold for a higher price than the usual single yolk eggs.
7.1 When the chickens arrive from a hatchery
See diagram 50.6.7 Chicken feathering record
See diagram 50.6.8 Chicken feathers (GIF)
1. When the chickens arrive, collect the chickens, open their box and give them some food and water.
2. Record number of chickens, date of arrival, number died before delivery, number of sick chickens on delivery, colour of feathers, colour of beaks, colour of eyes.
3. Note whether all chickens are eating.
If not, tap on the food container with a pen.
The chicken will think it is the sound of the hen's beak and it will start eating.
4. Note whether all chickens are drinking.
If not, catch a chicken and gently push its beak into the water to make it drink.
5. Study the chickens carefully.
Note the number of toes, earlobes, wattles, any sign of a comb and any abnormal features, e.g. twisted legs.
6. Note the colour and size of the first droppings.
7. Record any feathers on feathering records.
8. Note whether the chickens move about or stay together in one place, where do they go, the sounds they make and how they drink.
7.2 Caring for young chickens
See diagram 50.6.3.6: Holding a chick
Hold a baby chicken safely.
Hold the legs between the last 2 fingers of the right hand.
1. In some villages the people are not accustomed to caring for chickens.
Make a roster and put down the names of four students for each day to go to the brooder twice every day and do the following:
1.1 Replace newspaper covering the floor.
1.2 Empty the drinker.
Clean it with running water.
Fill it with clean water again.
1.3 Add food to the feeder.
1.4 Study each chicken carefully.
Look at the droppings.
If the students see anything that is not right they should tell the teacher straight away.
Every 5 days, record chicken weights and how many feathers are showing.
Protect young chickens
Prevent little chickens from dying when they are young.
Some chickens may be killed by hawks, or cats, dogs or other animals.
Some chickens die, because they get a disease.
Some little chickens die, because they do not get enough energy food and protein food.
However, if some food is put out for them to eat, dogs or big roosters and hens may eat the food and chase the chickens away.
7.3 Chicken brooders
See diagram 50.6.3.1: Simple electric incubator
See diagram 50.6.3.2: Warm brooder
See diagram 50.6.3.4: Electric incubator
See diagram 50.6.3.3: Brooder drinker
See diagram 50.6.3.5: Feeder box
Chickens require a uniform temperature for the first six weeks of their life.
In nature, the warmth of the hen's body gives the chicken enough heat, but when chickens are raised artificially a source of heat must be provided for them.
This is most economically provided by warm earth brooder or kerosene lamp.
1. Make a brooder to be ready before the modern laying chickens arrive.
Use it for the first 2 weeks.
You can make two kinds of brooder:
1.1. Make a cold brooder from a cardboard carton or a box 76 cm long and 37 cm wide to hold 12 small chickens.
The chickens can keep warm for the first 10 days of their life by moving between strips of old blanket, fixed to the roof at one end of the brooder.
Put the feeder and drinker at the other end of the brooder.
1.2 Make a hot brooder where the heat is provided by a kerosene lantern turned down low.
The brooder must be big enough so that chickens can move away from the kerosene lantern if they find it too hot.
2. Make drinkers from two tins of different sizes.
The smaller tin has a small hole made with a nail down near the open end.
This hole must be below the edge of the larger tin.
The larger tin is cut down to 4 cm deep.
3. Make a feeder from a chalk box so that chickens cannot stand in the food.
In warmer coastal places, the easiest method is by using a kerosene lamp and a sheet of 3-ply timber.
Cut a hole is cut in the middle of a 112 cm × 112 cm piece of plywood for the lamp.
The brooder should be 15-20 cm high from the floor.
Light the lamp at about five o'clock in the afternoon.
Nail pieces of bag 5 cm wide onto the 3-ply timber to keep the heat in and allow the chickens to go in and out.
In cooler highlands places, plenty of heat must be provided to keep the chickens warm.
The ideal temperature for a brooder is 35 oC, measured just inside the brooder and 2.5 cm above the floor.
If you do not have a thermometer, judge the temperature by putting a hand inside the brooder.
If the temperature feels pleasantly warm, the temperature is right for the chickens.
If it feels hot, turn down the wick of the lamp.
5. A warm earth brooder is suitable for many chickens.
You need a special house for this brooder, with a low ceiling, about 120 cm high.
Bury a 44-gallon drum half way into the earth.
Make a chimney, a vent for air and a hinged lid so wood can be put on the fire.
Provide protection around the drum so that the chickens cannot burn themselves on the hot drum.
Light the fire in the afternoon and adjust the air vent so the fire will burn all night.
This brooder is useful for the colder highlands.
7.4 Feeding young chickens
The food for the small chickens should be in very small pieces.
The wall of the feeder must not be too high for little chickens to eat out of it.
Day old chickens for meat or egg production require a 20% protein feed.
The feed contains a coccidiostat to prevent coccidiosis disease.
When buying feed for chickens, check the label on the bag to see whether the feed is medicated with a coccidiostat.
Feed the chickens the 21% protein medicated feed for the first six weeks.
If raising meat birds, then keep feeding this feed until the chickens are 9-10 weeks of age when they will be sold at the market.
If raising pullets for egg production, at the end of six weeks change the feed to a grower feed that contains only 15% protein.
Use the lower protein feed to save costs and to delay the maturity of the chicken when it starts to lay eggs.
By delaying maturity, the chicken will produce larger eggs when it starts to lay at about 24 weeks.
If a chicken is made to lay eggs at too young an age, most of the eggs it will produce during its life will be small eggs.
If the price received from small eggs is not as much as that received for large eggs, the more large eggs the greater the profit.
Commercial poultry keepers, usually buy feed, because they do not have enough time to grow feed crops.
7.5 House for young chickens
See diagram 50.6.3.8: Surround for young chickens
Choose a dry place to make the yard.
Put a fence or wall around the yard to keep other chickens and animals out.
Put in strong posts for the house.
Make walls and roof for the house.
Build a creep in the middle of the house with a cover that can be taken off to put food inside it.
Make a protected place where the hen can sit on her chickens.
Use a creep to stop dogs and the big chickens eating the food for little chickens.
A creep can be a small area surrounded by small sticks pushed into the soil.
The sticks are so close together that dogs and big chickens get inside this place, but small chickens can.
Make a cover over the creep to keep out dogs, other chickens and rain.
Build the creep under a roofed pen so the hen and her chickens can be put inside the pen, until the little chickens learn to find the food in the creep.
The house must have the following:
1. The house must be dry.
It must have a roof and good walls that keep out the rain.
Air vents in the walls must have hoods over the top of them to keep out the rain.
2. The house must be cool.
Do not use iron for the roof or walls.
Use materials such as palm thatch that allows air to flow through it.
Do not use plastic sheeting for the walls of the house, because no air flows through it.
3. The house must be safe to protect the chickens from cats, mongoose, owls, dogs, and human thieves who may steal the birds.
Predators can be kept out by putting wire netting or loose bamboo strips over all the holes.
The only way to keep out thieves is to put a door on the house and put a lock on this door.
4. The house must have enough space.
Laying hens need to have more space than meat chickens.
Twelve hens need 4.4 m2 of floor space.
A house 1.5 m × 3 m, or 2 m × 2 m is enough floor space for 12 hens.
5. The house must have perches.
Each chicken needs 23 cm of perch length.
So if the house is two metres long, use 3 perches two metres in length along one wall.
6. Cover the floor of the house with deep litter and put the chickens in a round "surround" with no corners, where for the chickens can huddle together and smother.
Use a two-metre surround for 250 to 300 chickens.
Keep the chickens confined for the first two weeks close to their source of heat, feed and water.
After two weeks gradually increase the area until at four weeks they can use the whole floor area of 100 cm2 per chicken.
You can remove the surround after two weeks, but block off the corners of the house to prevent crowding.
9.1 Egg laying, onset, clutches, cycle
1. Onset of lay or laying
A pullet (poult), is a young hen, 6 to 24 weeks old.
Modern chickens do not begin to lay until at least 20 weeks old.
Until they begin to lay, call them pullets.
Sometimes pullets start to lay in spring when the days are getting longer.
However, close to the equator, where there is not much difference in the length of the day in winter and summer, pullets may start to lay in any season.
When a pullet starts to lay, the first few eggs are often very small compared with eggs laid later in the lay period.
2. Clutches
Hens lay eggs in groups called clutches, e.g. a clutch length of 4 means she will lay an egg every day for 4 days.
Then she will stop laying and rest for a day before she starts laying the next clutch.
So a clutch is a set of eggs for hatching at about the same time.
3. Laying cycle
Each egg in a clutch is laid later than the one the previous day.
The rising sun in the morning starts an egg leaving the ovary.
If a hen takes 26 hours for an egg to be made and they start the first egg of a clutch at 5.00 a.m. and then will lay the next egg at 7.00 a.m. the next day.
The hen may wait an hour before the next egg starts being made, 8.00 a.m.
This egg will be laid the following day at 10.00 a.m.
The next egg starts being made at 11.00 a.m. and will be laid the following day at 1.00 p.m.
Then the hen will stop the clutch and have a day of rest, because hens do not lay eggs after 3.00 p.m.
Most eggs are laid in the morning.
4. End of lay or laying
When village chickens have laid about 12 eggs, they will usually stop laying and go broody, sit on the eggs until they have hatched.
Modern egg laying hens do not go broody so easily, but they usually stop laying in the Autumn when the days are getting shorter.
Then they lose many feathers, called moulting.
They will not start to lay again until new feathers have grown.
Also, hens may stop laying if they are sick.
5. Managing broodiness
Some chicken breeds get more broody than others and when one hen gets broody it affects the other hens.
Their behaviour changes, they stop laying and their pecking order changes.
Isolate the broody hens for three nights in an uncomfortable space, e.g. a milk crate, without straw.
They have food and water, but they cannot nest.
9.2 Egg preservation
1. "KePeg" will keep eggs fresh for a year without refrigeration.
Apply a solid coat over the egg shell, which seals the pores and keeps the oxygen from penetrating the shell, then store them in a cool dark and dry place for up to one year.
2. Oiled eggs will keep eggs for months, but will eventually develop an off-taste.
3. Pickled eggs
The eggs are boiled then put in a mixture of vinegar, salt, and spices, e.g. ginger, then put in beetroot juice for colour.
The acetic acid in vinegar dissolves the calcium carbonate in the shell.
Pickled eggs may keep for a year without spoiling.
4. Refrigerated eggs
Fresh eggs can be kept refrigerated for up to t6 weeks.
Refrigerated eggs should not be left out at room temperature for more than two hours befor cooking. The carton of eggs are delivered to a shop for sale, may have the recommendation that contents should be stored at 4 oC to 0 oC.
Fresh eggs are preserved by low temperature, cold storage just below freezing point and by excluding air by coating or immersing the eggs.
Eggs preserved by cold storage must be used soon after they have been removed from storage and thawed.
At home, eggs should be washed clean then kept in the refrigerator, usually in a rack in the refrigerator door where the eggs can be monitored, but some cooks say leave the eggs in their carton to avoid fridge smells.
Eggs lose moisture when chilled and the air space within the shell gets larger.
Discard cracked eggs or cook them thoroughly, because they may contain disease organisms, e.g. Salmonella bacteria.
Eggs can be broken into a bowl with some salt or sugar added, whisked thoroughly, then stored in ice block trays in the refrigerator.
5. Salted eggs
Salt is a good preservative, because it draws water out of bacteria and moulds to prevent their growth.
Chinese salted duck eggs are made by immersing in salt water or coating them with salt and mud or clay paste.
The orange-red yolks are solid, but the white is till liquid.
They are boiled before being eaten.
6. Waterglass
Waterglass is an aqueous solution of potassium silicate or sodium silicate, or a mixture of the two, which solidifies in the air and seals all the pores in the egg shell to preserve the eggs.
Commercial water glass is sold both as thick syrup liquid and as a powder.
Experiment
Dissolve 1 part of water glass in 10 parts of boiled water.
Pour the solution over the eggs packed in a suitable container and store them in a cool place.
Do not wash the eggs before preserving them, because this removes the natural mucilaginous coating on the outside of the shell.
To prevent the shells of eggs preserved in water glass from cracking when boiled, puncture the blunt end of the egg with a pin before putting it into the water.
7. Petroleum jelly
Warm the petroleum jelly, stir boracic acid into it.
Smear the mixture on new laid eggs.
Store the eggs in a ventilated cupboard.
8. Beeswax
Shred beeswax into a cup then cover it with olive oil.
Put the cup in a saucepan of water then stir the mixture in the cup over heated water.
Smear the mixture on new laid eggs.
Store the eggs in a ventilated cupboard.
9. Lime
Boil 1 cup of salt in 3 litres of water, leave to cool then add 2 cups of garden lime (calcium hydroxide), stir the mixture then pour it over the eggs.
Store the eggs in a ventilated cupboard.
10. Dried eggs
Egg powder was produced industrially for the armed forces during the Second World war.
11. "Hundred years old" eggs
Eggs are coated with clay, ash, salt, lime, and straw for long periods.
The yolk becomes a green-black with an odour of sulfur and ammonia compounds.
The while the white becomes a dark brown, translucent jelly with a tasty flavour.
The product is usually cut into 4 pieces and eaten raw in Chinese meals.
9.3 Egg production
1. Hens will lay 160-240 eggs in twelve months.
2. Losses from day old to 18 months should not be higher than 15-20% for the business to be economic.
3. Pullets will start laying at 24-26 weeks of age.
4. As a rough guide for budgeting for layers, the sale price of ten eggs should be ten times the price of 0. 5 kg of layer feed.
For example, 0.5 kg of feed costs six cents, therefore the sale price of ten eggs should be 60 cents.
5. Stop hens going broody and always sitting on their nest.
A hen goes broody is when she can feel many eggs underneath her or see many eggs in the nest.
The feathers of the broody hen are fluffed out and she makes a clucking noise.
So you can stop hens going broody if you collect the eggs from the nest.
However, village hens may hide their nests and make nests the same colour as the grass and the ground, so and seeing them is difficult.
Never take all the eggs away from a nest, because if a hen comes back to her nest and finds that all her eggs have gone, she may leave that place and make a nest in another place.
So leave three eggs in the nest.
Use China eggs or mark three eggs so you will know which eggs to leave each time.
6. You do not want to eat an egg that has started to turn into a chicken.
As an egg starts to turn into a chicken, the bubble of air at the round end gets bigger and the egg floats.
If you put eggs into a bucket of water, the fresh eggs will sink to the bottom, but eggs with a chicken inside, or bad eggs, will float.
9.4 Egg structure
See diagram 50.6.10: Parts of an egg
The shape of an egg is an ovate spheroid with one end larger than the other end.
The egg has cylindrical symmetry along the long axis.
An egg is surrounded by a thin, hard shell.
The egg yolk is suspended in the egg white (albumen), by one or two spiral bands of tissue, the chalazae.
The larger end of the egg contains the air cell that forms when the egg cools down and contracts after it is laid.
Study the component parts of a hen's egg and name the parts.
A hen's egg weighs about 60 g.
The shell weighing about 12% of the weight is porous to allow passing of air, water and odours.
Inside the shell is a translucent membrane that separates from the shell at the larger end of the egg to form an air chamber.
Brown shell eggs are not superior to white shell eggs and they may be smaller.
They are easier to examine for freshness, because the shell is thinner and less opaque.
Experiment
1. Examine egg contents
Tap a hen's egg against the rim of a dish so that the shell egg cracks in the middle.
Break open the two parts of the egg without using too much pressure, and let its contents flow into the dish.
Do not break the yoke!
The liquid white fills the egg apart from a small air space.
Inside the egg white, note how the albumen filaments, the chalaza, hold the yellow yolk in the centre of the egg.
The germinal disc, from which the chick develops, lies on the yolk mass.
The part of the yolk opposite the germinal disc is the heaviest, so the germinal disc always floats on the top of the yolk.
It receives the greatest amount of heat when the hen is sitting on the egg.
As the hen sits on the egg, a chick gradually develops from the germinal disc.
During this period, the yolk and egg white (albumen), nourish it.
When, after 21 days, the yolk and the white have been consumed, the chick is fully developed and hatches out of the egg.
2. Air from the air chamber
An egg has a pointed end and a round end.
The round end contains air.
As an egg gets older, the air increases.
Push a pin into this end by making a small hole in the shell.
The air comes out when the egg is put into boiling water to cook it.
9.5 Egg yolk
Lutein, C40H56O2, an xanthophyll pigment
As the yolk ages, it absorbs water from the albumen, which increases its size and causes it to stretch and weaken the clear vitelline membrane that enclosing the yolk, resulting in a flattened and enlarged yolk shape.
The yolk colour depends on the yellow-orange xanthophyll pigments in the diet of the hen.
Foods containing lutein, e.g. marigold petals, affect the colour of the yolk.
Double-yolked eggs occur rarely in young hens beginning to lay.
Yolkless eggs rarely occur.
Yolks of chickens allowed to select what they eat by free-range husbandry will differ from each other, because each chicken can select what to eat.
Commercially produced eggs with bright attractive yolks of similar colour come from chicken fed colouring agents, e.g. synthetic canthaxanthin, carotenoids, plant pigments in capsicum, marigold and paprika.
3. Break an egg carefully onto a plate.
The yolk is the yellow part in the middle.
It contains fat and protein.
Some people like eggs where the yolk is a dark yellow colour.
Chickens that have not had much green grass to eat may lay eggs with pale yolks.
Sometimes the yolk has a blood spot, but eating it is not harmful.
Blood spots may occur when the yolk breaks away from the ovary and starts to turn into an egg.
The yolk, about 30% of the total weight of the egg, is opaque and soft.
It congeals with heat.
It contains albumins, fats, lecithins, nucleins, chlorestins, and haematogen pigment.
It contains the germ that is visible in the fertilized egg.
9.6 Egg white
The white of the egg, albumen, about 58% of the total weight of the egg is viscous and transparent.
It contains about half the 14% protein content of the egg, water and minerals.
Albumen dissolves in cold water, but it congeals to become insoluble at 70 oC.
Both the yellow yolk in the middle of the egg and the white of egg around it contains much protein.
The white of egg also contains protein.
It is usually in two parts.
The thick white is next to the yolk.
The thin white is watery and spreads out on the plate.
In good eggs is much thick white and not much thin white.
In an egg also see the two cords that connect the yolk to the inside the shell.
The cords hold the yolk in the middle of the egg.
9.7 Tests for egg age and grading
See diagram 50.6.9: Egg calipers
As the air cell increases in size, the egg becomes less dense, and the larger end of the egg will rise to increasingly shallower depths in a bowl of water.
A very old egg floats in water and should not be eaten.
In a newly laid egg the yolk is round and firm.
Chicken eggs can be graded according to the size of the air cell, measured during candling.
A very fresh egg with a small air cell is given grade AA.
As the size of the air cell increases, the grade changes from AA to A to B.
In some countries in Europe, eggs are graded by weight from size 7 (< 45 g), to size 1 (> 70 g), but the main grades are size 4 (55-60 g), and size 3 (60-65) g.
Experiments
1. Tests eggs by candling.
Observe the air chamber.
A fresh egg has a small air chamber.
This procedure is called candling.
Test for double yolks by candling.
Hold up the eggs to a bright light to see the shadows of the two yolks.
2. Tests eggs for freshness
Test for freshness: A fresh egg feels heavy, but is loses a small fraction of its weight every day by evaporation of water through the porous shell.
Put eggs in salt water, 125 g of salt (sodium chloride), in one litre of water.
* Eggs up to three days old fall to the bottom of the solution.
* Eggs three to six days old float half way up the solution.
* Bad eggs float horizontally at the top of the solution.
Break an egg onto a flat plate.
* The yolk of a fresh egg is compact and stays in the middle of the white.
* The yolk of an egg one week old is not in the middle of the white.
* The yolk of an egg more than two weeks old spreads over the white.
Some cooks discard opened eggs if the yolk breaks and mixed with the white.
Also, eggs with any discoloration, chunky bits or bad smell should be discarded.
3. Float eggs to estimate age
Place a fresh egg in a solution of 1 part of salt to 2 parts of water.
From 1 to 36 hours old, the egg sinks completely, lying horizontally on the bottom of the container.
After 2 to 3 days, the egg sinks to just below the surface of the water, with a slight tendency of the large end to rise.
After 5 days the long axis of the egg floats at 20o from the perpendicular.
After 8 days 45o.
After 14 days 60o.
After 21 days 75o.
After 30 days 90o, so the egg floats upright with the point or small end downward.
The change in floating action is caused by the air cavity in the big end of the egg increasing in size and capacity as the egg grows older.
4. Test egg density
The density of eggs decreases with age, because of evaporation of water through pores in the shell.
Evaporation increases with increase in temperature.
A new laid egg placed in salt water will sink to the bottom.
A one-day old egg sinks below the surface, but not to the bottom.
A three-day old egg will sink just immersed in the liquid.
If more than three days old, the egg will float on the surface.
So more shell is exposed with age
Average relative density
Fresh eggs 1.090
After 10 days 1.072, loss of 1.6% After 20 days 1.053, loss of 3.16%.
After 30 days 1.035, loss of 5%.
9.8 Egg experiments
1. Cover a fresh egg with vinegar or dilute acid hydrochloric acid.
Change the solutions each day for 7 days.
Pick up the decalcified egg and drop it to show that it will bounce and not break.
2. Chemical egg peeler.
Put an egg in vinegar (contains acetic acid, ethanoic acid).
Note the bubbles forming on the outside of the egg.
Leave overnight then, the next day, pick up the egg with your fingers.
The egg has become soft.
Leave to stand for a week and the egg shell disappears completely.
You can now see through the raw egg.
acetic acid in the vinegar + calcium carbonate in the egg shell --> calcium acetate in solution + bubbles of carbon dioxide + water.
3. Remove the egg from the vinegar, dry it and shine a torch light on it in a dark room.
The egg without shell reflects the light.
4. Drop the dried egg on the floor.
The egg without shell bounces.
Measure the height of the drop and the height of the bounce.
Cooks may soak boiled eggs in vinegar to make pickled eggs, which may be eaten without the need for cooking.
5. Add 5 mL vinegar or dilute HCl or dilute H2SO4 or dilute HNO3 to pea size amounts of finely divided egg shell.
Continue to add the solid until no further reaction occurs.
Filter and evaporate the filtrate to dryness and note any visible changes.
6. Test any gas liberated by inserting in the mouth of the tube first damp pieces of red and of blue litmus paper.
Then a drop of limewater hanging on the tip of a glass rod and finally a burning splinter to show that gas is carbon dioxide.
8.1 Cages for layers
When the pullets start to lay, some people prefer to put them into laying cages instead of leaving them on the floor.
1. When you leave hens on a floor, they will form a social order and peck the lowest hens in the social order so much, that they get worried by the pecking and they do not lay as many eggs.
If you put each hen into a separate cage, then no hens will be worried by pecking.
2. When hens are put into separate cages, each hen has its own food and water so you can be sure that each chicken gets enough food.
3. When a hen lays an egg in a separate cage, it rolls down in front of the cage where it is easy to collect, and then the hen cannot peck at the egg and eat it.
Also, you can tell which hens are not laying.
Cages can be made with wire netting placed on supports so they are chest high.
The droppings fall onto the ground under the cages.
Instead of wire netting you can use bamboo sticks to make cages.
3.1 Put two rows of posts 48 cm apart in the ground with one row 6 cm higher than the other row.
The pairs of posts are 25 cm apart in the rows.
Use string to make sure that the posts in each row are all the same height.
Build a framework for the cages with squared timber.
Make 24 cages. Nail down the long narrow floor pieces of split bamboo with the round side up.
They must stick out of the cage on the lower side.
Leave a space between the floor strips to make a tray so that the eggs roll down into this tray and stay outside the cage.
The small spaces between the floor pieces let the droppings fall down to the floor.
Put on the sides between the cages using pieces close enough to stop a hen putting her head through it to peck the hen in the next cage.
Fix pieces of split bamboo to the front and back of each cage about 7 cm apart, so the hen can put her head through them to eat or drink.
Leave a space 6 cm at the bottom of the front, so the eggs can roll out of the cage.
Make a lid for the top of each cage from thin pieces of whole bamboo.
The pieces must be round and 7 cm apart so the hen can put her head up through the lid without getting cut by the sharp edges of split bamboo.
Tie the lid to the top of the cage with string.
Do not use nails.
Fix food and water troughs to the front and back of each cage.
4. In commercial operations, the cages are kept in long sheds, tunnels, and air is pushed through the tunnels by large fans.
5. Some people object to commercial "factory farming" using cages, because they say that the natural behaviours are prevented by over-crowding, e.g. flapping wings, dust bathing, scratching, pecking, perching and nest building.
Also, painful de-beaking operations may be used to stop cannibalism.
The European Union is expected to ban battery cages for egg laying hens, but some member states have suggested alternative actions to prevent cruelty, and preserve the intensive egg laying industry.
6. People who object to "factory farming" prefer "free range" laying hens given uncrowded outdoor access.
However, the term "free range" has no definition within commercial production industry.
The unpredictable diet of free range hens will produce unpredictable eggs.
8.2 How long to keep layers
Hens may keep on laying well for a while, but they will certainly go out of lay.
After having a rest the hens will start laying again for a second year.
However, in the second year the hens do not lay as many eggs as in the first year.
Usually, they lay between 60% and 75% of the first year of laying.
However, it is best to keep the hens for a second laying season, because they will not lay any small eggs in the second laying season.
Also, if there has been a lot of Marek's disease this will have been mostly in young birds.
Chickens more than one year old are less likely to die from Marek's disease.
8.3 Housing layers
Layers can either be housed on deep litter or be allowed to run outside.
If they are fed properly, you can to keep them on deep litter.
If they outside they may be killed by dogs or infested with worm internal parasites that lower their production and affect their health.
On a commercial poultry farm, keep the chickens on a deep litter floor.
Management of the laying hens is very easy if they are on deep litter, because you only have to feed and water them daily.
Keep the feed and water troughs clean.
Rake over the deep litter material twice a week.
Collect the eggs twice daily, at 11.00 a.m. and 3.00 p.m. so there will be fewer broken eggs and the hens will be less likely to start eating their own eggs.
If you see any sick birds, remove them immediately from the house.
The hen prefers a comfortable and relatively dark place with sawdust, coffee skins or soft grass in the nest to lay her eggs on.
Provide one nest for every 4 birds.
The nest should be placed about 45 cm above the ground.
Use a four-gallon kerosene tin with half the top cut out to make a nest.
Find a hen that will soon hatch out her chickens or has just done so.
Find the place the hen chooses for making a nest.
Look for nesting places that hens have chosen.
Hens like the nesting place to be a little dark.
They do not like too much light.
They like places with a small entrance and more room inside.
They do not mind if they have to push through some leaves or grass to get inside the nest.
They like to have some cover over their heads when they sit on the nest.
They do not like strong sun shining on them or rain falling on the nest.
Hens like the nesting place to be a private and that they cannot be seen easily.
Hens like nests that are low down or right on the ground and are comfortable with soft litter in the nest.
Make a place where hens can pick up small pieces of stick or grass or feathers.
They like to pick up these things in their beaks and put them on their backs.
If you are making a nest, then you can put some of these small things around the nest.
It must be in a dry place.
If the ground is in a hollow or low place, then the level of the soil can be built up.
To make the hen go broody, put a nest egg in the nest.
When hens they are looking for a place to make a nest they like isolation, darkness, head cover, small entrance, low level, small pieces to pick up and dryness.
8.4 Point of lay
1. The first eggs laid by pullets are usually very small, but larger eggs will soon be laid.
There may be no small eggs laid if the chickens have not been given all the food they need.
Restricted feeding is sometimes used to help stop Marek's disease.
The chickens start laying later than 22 weeks, but the first eggs are usually big.
2. Record the age of the pullets when they started laying.
3. Hens cackle after laying an egg, so this the sign that they have laid.
It is also a sign to any roosters that they are again ready to mate.
4. Record the clutch length of a hen.
Mark a certain hen and record the times when she lays an egg on two successive days.
Usually the second egg will be laid about 26 hours after the first egg.
Then calculate the clutch length, because no eggs will be laid after 3.00 p.m.
5. Collect and record the eggs taken from each nest.
8.5 Laying hens
Laying hens require 0. 25 m2 of floor space if kept in a deep litter pen.
Provide roosts, egg nests and clean water.
Feed green feed once a day.
Provide a box of crushed coral or shell grit for the chickens to peck, so that they get plenty of calcium to make the egg shells strong.
Also, provide hard grit or very small stones in a separate box for the birds.
Poultry do not have teeth so they eat hard grit held in the gizzard to help grind the feed.
The chickens are fed a 16% layer ration in a self-feeder once a week.
As with chickens and growers, turn the deep litter material once a week.
The nests must have clean grass or coffee hulls in them to be changed every two weeks.
If you see clucky or broody hens, i.e. chickens that sit on the eggs to hatch them, put them in a separate wire cage for three days.
Good layer management requires the following:
1. Give correct feed.
Use a creep to give food to small chickens.
2. Make clean water available at all times.
3. Make green feed available once a day.
4. Make shell grit and hard grit available in separate boxes.
5. Houses must be waterproof and free of draughts.
6. Plenty of roosting space and nests are necessary.
7. Turn deep litter once a week.
8. Nesting material must always be clean to keep eggs clean.
9. Collect eggs twice a day.
10. Cull layers at 18 months of age.
Commercial producers may cull between 100 to 130 weeks of age, when their egg productivity starts to decline.
11. Keep the layer house away from the young stock shed.
12. Clean houses out thoroughly before putting in new stock and rest for three weeks.
8.8 Nests for layers
At about 20 weeks of age, provide nests for the pullets to start laying.
Hens like nests to have the following features:
The nests are:
1. dry,
2. a little dark, with a small entrance,
3. with head cover,
4. isolated from other objects in the house,
5. low down,
6. soft, so that a hole can be scratched in the middle of the nest,
7. near small pieces of grass, feathers or sticks, close to the nest that the hen can pick up in her beak,
8. and have a hole at the back to give air flow through the nest.
Sometimes you can help a pullet to start laying if you put in the nest a china egg or a round stone about the size of an egg.
Place the nests up against the wall of the house in a corner.
Never use steel or iron drums for making a nest, because they get too hot on hot days.
Provide one nest for every 4 or 5 hens.
So for 12 pullets, you need 3 nests in the corner of the house.
Three types of nest:
1. Take out one of the narrow side boards of a wooden box.
Cut apiece off it and put it back to make a support to hold the nest material in place.
Use wood to cover up half the open side and make a small entrance.
Cover any gaps between the boards that let in light with using bags to make the inside darker.
Put soft grass material inside the box and small pieces of grass just outside the nest.
Make a small hole in the back so that cooling air can flow through the nest.
2. Use a cardboard carton from a store.
Cut away part of a side.
Make a hole in the back for ventilation also.
3. Use 4 strong sticks about 60 cm long.
Sharpen the ends and drive them into the ground close to the wall so that their tops are close together.
Tie the tops together firmly with string.
Put a cover over the sticks, but leave two holes:
1. a big hole on one side for the hen to enter and
2. a small hole on the other side for air flow.
To cover the sticks, use thatch, paper, cardboard or woven wall materials.
8.7 Modern egg laying chickens
The White Leghorn breed is all white and has a small body, with a big red comb.
Some may have patches of black or red colour and white, because they are crossbreed hybrid laying chickens.
These chickens can lay many eggs when they grow bigger, but they must have good food and good care.
They need much more care than the village chickens.
They will need their own house with a roof and fence, a brooder, feeders and drinkers, a creep, nests, good food.
When the little chickens arrive, give them food, water and shelter.
Imported chick food is expensive, but makes the chickens grow quickly.
The chickens will arrive in a box but you have no hen to care for them.
So make a brooder where the chickens will be warm and be cared for during the first 10 days.
After the chickens leave the brooder, they must grow to a big enough size before they can start to lay eggs.
You may need to care for them for 20 weeks before they are ready to start laying.
In places where the difference between the length of the day in winter and in summer is large, the hens start to lay best in the spring when the length of the days is getting longer.
However, in tropical countries the length of the day does not change very much and pullets will start to lay any time.
8.9 Roosters
Roosters are not necessary for hens to lay eggs.
They are only necessary only if you want to breed chickens.
If the chickens are kept only to sell their eggs, then they will lay more eggs if no rooster is kept with them.
Male birds of a laying breed are usually not used for meat production, so are usually culled at the hatchery.
Fertilized eggs will stay fresh for only three days, but unfertilized eggs will stay fresh for at least a week.
Roosters are used for illegal cock fighting in undeveloped countries, by attaching a gablock, a spur, to the heel of the fighting cock.
8.6 Management and feeding of laying hens
The laying hen requires a 16% protein food and a well balanced ration called a layer ration.
The following are some of the suitable feed mixes:
1. Feed mix: Grain (wheat, rice, corn i.e. maize, or sorghum), mixed with poultry concentrate.
All the necessary minerals, vitamins, proteins and carbohydrates are balanced when poultry concentrate is used, but it costs more than if you grow the feed plants.
Rations using imported concentrate and locally produced grains
Table 17.1
-
 Starter / broiler
ration (20%)		 Grower
ration (15%)		 Layer
ration (16%)
Grain 70 kg 80 kg 71 kg
Poultry concentrate 30 kg 20 kg 29 kg
Total feed 100 kg 100 kg 100 kg

2. Feed mix
Use home-grown soybeans and grain
The vitamin supplements are usually not expensive.
Rations using locally grown feeds
Table 17.2
-
 Starter / broiler
ration		 Grower
ration		 Layer
ration
Soybeans 30 kg 10 kg 20 kg
Meat meal 10 kg 10 kg 9 kg
Grain 60 kg 80 kg 71 kg
Vitamin
supplement		 40 g 40 g 40 g
Salt 225 g 225 g 225 g

3. Feed mix
Grow sweet potato and mix it with poultry concentrate
Sweet potato is very low in protein and the chickens will not grow or lay eggs if fed sweet potato only.
Feed needs for one chicken for the different ages:
Concentrate / sweet potato rations for different ages of poultry
The figure in the concentrate and sweet potato column is the amount of feed each chicken will eat for that period of its life.
Table 17.3
Age of bird Concentrate
(kg)		 Sweet potato
(kg)		 Total
(kg)
0-6 weeks
(+ broiler ration)		 0.30 1.50 1.80
6-26 weeks 1.90 17.10 19.00
6-18 months 8.60 77.50 86.10

4. How much feed to give to ten chickens each day.
The sweet potato is cooked and then mixed with the protein concentrate.
Feed needs for a 10 hen layer enterprise feeding concentrate and sweet potato
Table 17.4
Age of Bird Concentrate Sweet Potato Total
0-6 weeks (+ broiler ration) 70 g 340 g 410 g
6-26 weeks 160 g 1.43 kg 1.59 kg
26-78 weeks 2.30 g 2.13 kg 2.36 kg

5. Feed consumption rates for grain rations 1
Table 17.5
Week after hatching 100 chickens will eat
1st week
2nd week
3rd week
4th week		 4.50 kg feed
9.0 kg feed
13.5 kg feed
8.0 kg feed

6. Feed consumption rates for grain rations 2
Table 17.6
Total Feed Consumption 100 chickens will eat
To 4th week
To 6th week
To 8th week
To 12th week
To 24th week
 45.4 kg feed
95.3 kg feed
163.4 kg feed
345.0 kg feed
908.0 kg feed

7. Spaces and roosts
Table 17.7
_
 0-4 weeks
 4-10 weeks
 10-20 weeks
 Adult chicken
Floor space
(m2 per bird)		 0.05 0.1 0.25 0.4
Feeding space
(m per 100 birds)		 1.8 3.0 4.26 6.0
Water space
(m per 100 birds)		 0.6 0.9 1.8 2.4
Roosts
(m per 100 birds)		 -
 9.0 15.3 18.0

Modern chicken rations contain every kind of food needed by the birds:
1. Energy food, e.g. wheat meal.
2. Protein food, e.g. fishmeal or meat meal.
They may also contain extra parts of proteins called amino acids, e.g. lysine.
3. Vitamins, including vitamin D if the chickens cannot get sunshine.
4. Minerals.
5. Medicated rations, e.g. drugs to prevent coccidiosis disease.
5.1 "Chicken starter" for very young chickens contains a good energy food and about 21% protein for meat chickens or 20% protein for egg breed chickens.
Chicken starter is so rich in protein that it is the most expensive to buy, but it can be used for only the first four weeks then changed to "chicken finisher", or "grower ration".
5.2 "Chicken finisher", or "grower ration" is used for growing meat chickens, called broilers.
The protein percentage is about 18%.
It can also be given to laying pullets, but they are usually given a ration with less protein, e.g. 17%.
5.3 "Laying ration" is for laying hens and contains at least 16% of protein.
5.4 If buying modern chicken rations for the first time, buy a small quantity of chicken starter to give the chickens a good start then change to local rations at 4 weeks of age.
The starter ration should be medicated to prevent coccidiosis disease.
8.10 Timing of replacement stock
Cull, i.e. sell or dispose of, the laying stock at 18 months of age, after they have been laying eggs for 12 months.
If chickens are kept longer than 18 months, it will cost more to feed them than the money received from the sale of eggs.
Time the replacement of laying stock so that they will start laying eggs when the layers have reached 18 months of age.
As it takes a chicken 6 months, i.e. from day old to 26 weeks, to be raised before it starts to lay eggs.
So the replacement stock must be bought as day old chickens, when the laying stock on the chicken farm are 12 months of age.
The replacement chickens will start to lay eggs just as the older layers turn 18 months of age, so cash income will not be interrupted.
See from the table how to time the replacement stock to replace the old layers, without interrupting egg supply.
Table 8.10
* Start batch 1, Day old chickens * 6 Months, Start laying * 12 Months, Buy replacements, Start laying, Start batch 2 * 18 months, Cull layers * Start batch 2, Day old chickens