School Science Lessons
(ProjChick2)
2024-08-28
Chicken Project 2 Chicken diseases
See: Websites Chickens
Contents
10.0 Chicken diseases
17.0 Chicken egg, (Experiments)
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
1.16 Records
10.0 Chicken diseases
10.1 Baccillary white disease
10.2 Botulism or food poisoning
10.3 Chronic Respiratory Disease (CRD) (mycoplasmosis)
10.4 Coccidiosis
10.5 Fatty liver of laying hens
10.6 Fowl cholera
10.7 Fowl pox
10.8 Lymphoid leucosis
10.9 Marek's disease
10.10 Vitamin deficiencies
11.0 Chicken hatching
11.1 Cardboard box incubator
11.2 Care for chickens
11.3 Castrated capon raising the chicks as a eunuch mother
11.4 Development of chicken embryo
11.5 Development of hatched chickens
11.6 Find the sex of the chickens
11.7 Hatching an egg
11.8 Incubators, brooders
11.9 Measure eggs
11.10 Study the development of the hatched chickens
11.11 Styrofoam cool box incubator
11.12 Unfertilized chicken egg
11.13 Warm brooder
15.0 Killing chickens
15.01 Killing chickens
15.1 Killing by the neck chop method
15.2 Killing by neck dislocation
15.3 Eviscerating the carcass
12.0 Prepare chickens for food
Domestic fowls used for food are called poultry, e.g. chickens, ducks, geese, turkeys.
12.1 Receiving poultry supply and thawing
12.2 Grading and packaging poultry
12.3 Poultry grades
12.4 Poultry composition
12.5 Poultry structure
12.6 Preparation prior to cooking poultry
12.7 Cooking poultry
12.8 Quality points of poultry
12.9 Drawing a chicken
12.10 Trussing a chicken
12.11 Jointing a chicken
12.12 Chopping a chicken Chinese style
12.13 Boning a whole chicken breast
12.14 Carving a chicken
13.0 Prepare eggs for food
13.1 Boiled eggs
13.2 Cholesterol and fat in eggs
13.3 Contamination by bacteria
13.4 Egg allergy
13.5 Egg grades
13.6 Egg sizes
13.7 Enjoy eggs every day!
13.8 Float eggs in water
13.9 Food labels, eggs
13.10 GMOs and chicken feed
13.12 Nutritional value of eggs
Poaching
16.3.8 Prepare egg recipes
17.0, Chicken egg, (Experiments)
Catch an egg in a sheet: 17.6.1.6, (Physics)
Chemical egg peeler: 12.3.9.0
Dilute acids with carbonates, common carbonates: 12.3.9.0
Dilute tartaric acid with egg shell, soil, wood ash: 12.3.9.4
Egg in a bottle: 12.3.27, (Physics)
Egg in a candle flame: 8.1.12, (Physics)
Eggs cooked in a microwave oven: 19.3.5.4, (See: 5. Eggs...)
Egg shells, Calcium carbonate
Egg white
Egg yolk
Prepare egg recipes: 16.3.8
Elevation of boiling points, ebullioscopic constant, kB: 7.5.1, (Boil an egg, Experiment)
Ethanoic acid, CH3COOH, acetic acid: 12.3.0.6, (See: 2. The bouncy egg experiment)
Household, Stain removal: 19.4.2.1, (Egg)
Osmosis with a chicken egg: 9.171
Prepare eggs for food: 23.0, (Chicken project)
Rotten egg gas, hydrogen sulfide, H2S
Secret writing inks, 3.2.5.1, (See: 2.)
Spinning eggs, forces with a fresh egg and hard-boiled egg: 16.3.25
Egg white
Albumen (egg white) and egg yolk: 16.7.10
Colloidal nature of egg white: 9.172
Egg white: 9.6
Fibrous and globular proteins: 16.3.6.0.2, (See: 3.)
Kjeldahl method for determining nitrogen content: 16.6.9, (See: 2.)
Leavening agents: 19.1.6.0, (See: 1.)
Prepare Meyer's albumen solution: 2.3
Prepare protein solutions: 16.5.1
Use egg white beaten solution to make leather upholstery look like new!
Egg yolk
Choline: 16.7.21.1
Egg in a cake mix: 16.7.10.2
Egg yolk: 9.5
Astaxanthin, C40H52O4
Colloids in food: 19.2.0.1
Prepare mayonnaise and salad dressing emulsions: 16.7.12
Phospholipids: 16.3.3.0.1
Rotten egg gas, Hydrogen sulfide, H2S
Acids with salts: 12.3.15
Float eggs in water: 13.8
Hair straightening: 19.5.6
Heat iron with sulfur: 12.2.2.1
Hydrogen sulfide, hazards: 3.8.7
Prepare hydrogen sulfide: 3.43.0
11.7 Hatching an egg
See diagram 50.6.10: Parts of an egg
Keep records of the egg during the 21 days to hatching.
Measure and record the weight and length of the egg on days 3, 7, 14 and 21.
Use a strong light to see the developing chick.
They call this candling, because formerly people used a candle to see if the chicks were alive and developing properly.
Note the heart of the developing chick already beating by day 7.
Note the change in the weight of the egg, but no change in the length of the egg.
The mass changed, because reserve materials were broken down into carbon dioxide and water by respiration.
The carbon dioxide and water vapour could diffuse though tiny pores in the shell causing the loss of weight.
11.9 Measure eggs
See diagram 50.6.9: Egg calipers
See diagram 50.6.10: Parts of an egg
1. Keep records of the eggs during the 21 days to hatching.
Each day do the following:
* weigh the fertilized eggs
* measure the length of the egg with a pair of calipers
* Record the measurement in a table.
Examine the tables and note whether the weight and length change.
Weight is lost when food is broken down during respiration to carbon dioxide and water that can both diffuse out through the egg
membranes and the shell.
2. Weigh a fertilized egg and record in a table.
Measure the length of the egg with a pair of caliper and record in the table.
Record the weight and length of the egg each day.
Note whether the weight changes and whether the length changes.
Weight decreases how is it lost?
Food is broken down during respiration to carbon dioxide and water, which can both diffuse through the egg membranes and the shell to cause weight loss.
At the end of three days remove one egg and crack it carefully.
Put the contents into a shallow saucer.
A three day embryo will usually show the heart already beating.
It may continue to beat for half an hour.
Remove an egg at day 7, day 14 and day 20 to study the development of the embryo.
Leave eggs for 21 days to hatch.
When the first cracks in the egg appear at day 21, the chicken is about to hatch.
The chicken cracks the egg with its egg tooth, a hard lump on its beak.
Find the egg tooth in a day 20 chicken.
11.8 Incubators, brooders
1. Make a cardboard box incubator
See diagram 50.6.3.2: Simple incubator
Use a large and small cardboard box.
Cut one end from the small box.
Cut a 15 cm2 window in a side of the large box.
Cut a slit in the top of the smaller box and suspend an electric lamp in it by a long electric cord.
Put the small box inside the larger box and pack newspaper between them.
The open end of the small box must fit against the side of the large box in which you cut the window.
Put a thermometer in the box so that you can read it through the glass window.
2. Make a Styrofoam cool box incubator
See diagram 50.6.3.4: Warm brooder, electric incubator
See diagram 50.6.3.3: Brooder drinker, feeder box
Make a hole in the side of a Styrofoam box to fit a 40 watt light bulb socket.
Put aluminium foil on the bottom of the box.
Put a piece of wire mesh across the box.
Make air holes in the sides and in the lid of the incubator.
Also, make a hole in the Styrofoam for a thermometer.
Maintain a constant temperature of 38oC in the incubator for 21 days.
Use different sized bulbs and change the newspaper to regulate the temperature.
Put a dish of water in the incubator.
Put 12 fertile eggs in the incubator.
After three days, remove one egg and carefully crack it open into a dish.
Study the beating heart.
It may continue to beat for half an hour.
Remove an egg every three days and observe the development of the embryo.
Leave eggs for 21 days to hatch.
11.4 Development of chicken embryo
1. Use fertile eggs from a chicken or from a poultry farmer with roosters in their flocks.
Immediately put the eggs on their sides inside the incubator at a temperature that should always be close to 38oC.
Eggs sold in stores or supermarkets are usually infertile.
The relative humidity should be 55% so put a pan of water or a wet sponge in the incubator.
2. Turn the eggs three times a day until day 18 to stop the yolk sticking to the shell.
Put a pencilled cross on the egg each time you turn it and move the eggs to different places.
3. Monitor the development of the chicks by "candling".
Hold the large end of the egg up to an electric light in a dark room after the 4th day of incubation.
The egg contents are pink when the embryo is developing properly.
As the embryo grows, it occupies more of the space within the shell until near hatching it occupies all of the space except for the air cell.
4. Remove the eggs if they appear clear (infertile eggs), or if they do not show much development at 10 days (dead embryos).
The air cell increases in size during incubation depending on temperature and humidity as moisture evaporates from the egg.
5. Note the heart of the developing chick already beating by day 7.
6. After three days, remove one egg and crack it open carefully.
Put the contents into a shallow saucer.
A three-day embryo will usually show the heart already beating.
It may continue to beat for half an hour.
7. Remove an egg at day 7 and day 10 to study the development of the embryo.
Leave the remainder of the eggs for 21 days to hatch.
Listen to the eggs during the final 3 days.
8. When cracks or a little hole appears at day 21, the chicken is about to hatch.
Do NOT try to help the chick out of the shell even if it takes a day to get out.
The chick cracks the egg with its egg tooth, a hard lump on its beak.
Find the egg tooth in a chick.
When the chicks have dried and become fluffy, remove them from the incubator.
9. Hold a light close to the egg so that you can see through it.
As the chicken develops, see its outline or shadow.
Put the egg inside the incubator and close the lid.
The temperature should be 40oC.
Roll the eggs every 12 hours to stop the yolk sticking to the shell.
10. Study an unfertilized egg.
Put a flat dish or Petri dish on black paper.
Break open a hen's egg.
Note the yellow yolk and the clear part.
Note the clear part, commonly called the "white" of an egg, because it turns white when cooked.
On the yolk see a small white patch.
In the centre of this white patch, too small to see with the eyes, is a nucleus.
This is where the chicken starts to develop.
1. Development of the chick in the egg
Before egg laying:
Fertilization
Division and growth of living cells
Segregation of cells into groups of tissues
Between laying and incubation: No growth, stage of inactive embryonic life
During incubation:
First day:
16 hours: First sign of resemblance to a chick embryo
18 hours: Appearance of alimentary tract
20 hours: Appearance of vertebral column
21 hours: Beginning of formation of nervous system
22 hours: Beginning of formation of head
24 hours: Beginning of formation of eye
Second day:
25 hours: Beginning of formation of heart
35 hours: Beginning of formation of ear
42 hours: Heart begins to beat
Third day:
60 hours: Beginning of formation of nose
62 hours: Beginning of formation of legs
64 hours: Beginning of formation of wings
Fourth Day:
Beginning of formation of tongue
Fifth Day:
Formation of reproductive organs and differentiation of sex
Sixth Day:
Beginning of formation of beak
Eighth Day:
Beginning of formation of feathers
Tenth Day:
Beginning of hardening of beak
Thirteenth Day:
Appearance of scales and claws
Fourteenth Day:
Embryo gets position suitable for breaking the shell
Sixteenth Day:
Scales, claws, and beak becoming firm and horny
Seventeenth Day:
Beak turns towards the air cell
Nineteenth Day:
The yolk sac begins to enter the body cavity
Twentieth Day:
Yolk sac completely drawn into body cavity
Twenty-first Day:
Hatching of chick.
11.10 Study the development of the hatched chickens
Be careful! Use safety glasses and thick gloves when handling the chickens
See diagram 50.6.7: Feathering record: Record the feathering by drawing feathers on the outlines of the chickens
See diagram 50.6.8: Feathers: A contour feather, B flying feather, C down
feather, D pin feather, E shaft F vane
Keep a chicken diary to record the weight, height and behaviour of the chicken each day for the first three weeks.
1. Weigh a newly hatched chicken and record the weight in a table.
Plot a graph of the changes in weight.
2. Use calipers to measure the height of the chicken from the top of its head to its feet.
3. Describe the change in colour, shape and development of its feathers.
4. Describe how the chicken walks when it first hatches and how this walk changes later.
5. Describe its "cheep" cry when newly hatched and how its voice changes later.
6. Describe how it pecks at its food, and drinks its water.
7. Record any other observations about the chicken.
8. Record changes in the mass of the chicken from day 1 to day 20.
9. Plot a graph of the changes in weight of the chicken.
10. Plot a graph for the changes in the height of the chicken.
11.6 Find the sex of the chickens
Be careful! Use safety glasses and thick gloves when handling the chickens.
For "sexing the chickens", turn the chicken over in the palm of the hand with its head pointing towards you.
Try to find the opening underneath its tail.
Use the thumbs to fold down the feathers.
Fold the skin down around the opening, but do not press too hard.
If the chicken is a male, see the penis like a small piece of thread.
The chicken is a female if the penis cannot be seen.
11.2 Care for chickens
See diagram 50.6.3.2: Warm brooder
A hen sitting on eggs keeps them warm.
When the chickens hatch, they huddle under the hen for warmth and protection.
If no mother hen, keep the chickens warm with a heater in a brooder.
This is a box with a heater or light.
The heater or light keeps the chickens warm.
Give the chickens food and clean water.
Use shallow dishes for the food and water.
At first give the chickens a handful of chicken mash.
Each day, add more food to the dish each day and provide clean water.
11.3 Castrate capon raising the chicks as a eunuch mother
A cock can be a mother.
In a village in the north of Anhui Province in China they ran an enterprise for raising chicks.
The peasants could use the castrated capon to protect and raise the chicks.
People bought the chicks from the hatchery.
They gave rice liquor to the castrated capon and the chicks in the same roost.
Later, the chicks, which had never seen their mother, were getting impressions of the image, movement, sound and temperature of the castrated capon.
The chicks jostled forcefully under the wings of the castrated capon as if in their mother's bosom.
The castrated capon clucked like a hen.
Later it protected the chicks and taught them to peck, call, defence themselves and preserve heat.
The effect was better than a hen.
Peasants sum up their experience and think it had three merits:
1. The castrated capon not only has large body and many feathers, but also can raise 40 to 50 chicks, as many as two hens do.
2. It can raise chickens for a long time.
A hen raises the chicks only for a month, but the castrated capon can do it for half a year until the chicks grow up and weigh 1 to 2 kg.
3. The castrated capon is more daring, fiercer and more thoughtful than cats and will not let cats get close to the chicks.
They can even wrestle with an eagle so they can raise the chicks' survival rate.
13.8 Float eggs in water
See diagram 11.285: Floating egg
1. After the egg is laid and it starts to cool, the air cell forms.
In a fresh egg the air cell is quite small and the egg sinks to the bottom of a container of clean water.
A fresh egg has a thick white that does nor spread out far in the pan and the yolk stands up.
As the egg gets older it loses water by evaporation.
The water is replaced by air so the egg decreases in weight and starts to stand up, smaller end down.
Later the egg starts to rise to the surface of the water.
2. Place an egg in a glass of tap water.
Add salt to the water to increase the relative density of the water make the egg float.
Ships float higher in salt water than in fresh water, because salt water is more dense than fresh water.
3. A floating egg to be used for cooking may be bad, so it should be opened in a separate container and discarded if any bad smell can be detected.
The bad smell comes from hydrogen sulfide, H2S (rotten egg gas), produced by the decomposition of proteins in a rotten egg.
Such an egg may contain the dangerous Salmonella bacteria that can cause sickness and death.
So some people never use floating eggs for cooking!
11.5 Development of hatched chickens
Be careful! safety glasses and thick gloves when handling the chickens
See diagram 50.6.8: Feathers
See diagram 50.6.7: Feathering record
Keep a chicken diary to record the weight, height and behaviour of the chicken each day for the first three weeks.
1. Weigh a newly hatched chicken and record the weight in a table.
Plot a graph of the changes in weight.
2. Use calipers to measure the height of the chicken from the top of its head to its feet.
3. Describe the change in colour, shape and development of its feathers.
4. Describe how the chicken walks when it first hatches and how this walk changes later.
5. Describe its "cheep" cry when newly hatched and how its voice changes later.
6. Describe how it pecks at its food, and drinks its water.
10.4 Coccidiosis
Coccidiosis is caused by single celled parasites that live in the gut wall.
It is spread when one chicken eats faecal material, droppings, from an infected chicken, which contains small egg-like bodies called oocysts.
Oocysts can remain alive in poultry sheds for more than a year.
It is impossible to prevent this spread unless chickens are housed so that they have no contact with faeces.
Affected chickens become depressed, lose condition and are very pale.
The feathers are ruffled and the wings droop.
There is usually diarrhoea and blood in the droppings.
They may not eat very much and very often they die.
The coccidiosis parasite needs moisture to become infectious so the litter must be kept dry, ventilation must be good and chickens should not be overcrowded.
Effective live vaccines and drugs called coccidiostats are available.
Coccidiosis may occur if coccidiostat level in the feed is too low, or is withdrawn too early before immunity has developed or if the chickens not eating enough.
Put a coccidiostat in the drinking water for 4 to 6 weeks and watch the chickens in case a lot of blood appears in the droppings, then the disease has started again.
Marek's disease
It is caused by a herpes virus that may result in death or severe production loss in both layer and meat chickens.
Vaccination will reduce the losses.
It causes changes in nerves and tumours in the major internal organs.
It is shed from the feather follicles and spreads in fluff and dust, gaining entry when the chicken breathes infected dust particles.
Once present in a flock, it spreads rapidly to unvaccinated poultry.
Chickens between 10 and 24 weeks of age are the most susceptible.
In the nervous form the chickens are unable to stand, become paralysed, waste away from lack of food and water and become blind.
In the visceral form grey-white tumours are found in the ovaries and other organs.
The chickens may show signs of depression, paralysis, loss of appetite, loss of weight, anaemia (pale combs), dehydration (shrunken combs).
Treatment is not effective.
Diseased chickens should be removed from the flock and destroyed.
Protection is obtained by buying chickens vaccinated either at day old or into 18-19 day old embryonated eggs (before hatching).
Isolate vaccinated chicks during their first two weeks of life so that their immunity will develop.
Rear chicks separately so that they are free from the infected fluff and dust of older birds.
Have a thorough clean out and disinfection of sheds and equipment between batches of chicks with a disinfectant effective against bacteria and viruses.
Exposure of the sheds and runs to sunlight helps the disinfection process.
10.3 Chronic respiratory disease (CRD) (mycoplasmosis)
It occurs when chickens infected with Mycoplasma gallisepticum are stressed.
The subsequent invasion by secondary bacteria causes the major damage to the bird.
Outbreaks occur at times of stress, e.g. moving, chilling, vaccinating, beak trimming, worming, poor ventilation, damp litter and ammonia build up.
The disease is introduced by infected carrier chickens or transport by persons who have handled CRD-infected birds.
The chickens show sniffing, rattling, sneezing, coughing and wet noses with retarded growth in growing chickens and a production loss in hens, but deaths are few.
Similar diseases are Coryza, Infectious bronchitis, and Fowl cholera.
Antibiotics will help control the disease and minimize secondary bacterial complications, but do not control the disease completely.
Suppliers of point of lay pullets can provide vaccinated pullets.
Mycoplasmosis, is caused by very small micro-organisms called mycoplasma.
These are breathed out into the air by diseased chickens and are breathed in by healthy chickens.
Control this disease by keeping very young chickens apart from older birds.
Then the microbes cannot reach them.
If the chickens catch this disease, it will quickly go from one to the others.
When the chickens have left this house, you must clean out the house and leave it empty for two weeks before you put any more chickens into it.
This disease does not kill chickens very often, but it causes them to lay fewer eggs and to grow slowly.
10.8 Lymphoid leucosis
It also causes tumours in organs, but does not cause paralysis.
It is usually seen in chickens over 16 weeks of age and is a disease of the nervous system.
It occurs more in older stock and growing pullets than in young birds.
There is no cure for Leucosis.
A vaccine has been developed that will lower the incidence of the disease.
The chickens should be vaccinated by hatcheries at day old.
The chickens appear quite healthy, but will have lost control and use of their legs.
You can eat these chickens as the meat is not affected.
Chickens that get Leucosis will not recover and should be destroyed.
10.7 Fowl pox
It is spread by mosquitoes.
It occurs mostly in chickens from 1 week to 10 weeks of age.
The eyes, beak and head will be covered with scabs.
Most of the chickens will recover from the disease, but their growth rate slows.
Chickens bought from a hatchery should be vaccinated against fowl pox as vaccination is the only cure.
There is no drug treatment.
10.10 Vitamin deficiencies
These deficiencies rarely occur in chickens that are free ranged or fed a balanced ration.
However, if the feed is very old then some of the vitamins such as Vitamin A may be deficient.
You can feed only fresh bought feed, add 40 g /100 kg of feed of a vitamin supplement to the ration and allow the chickens to free range for 1-2 hours per day or add fresh green feed to the chicken ration.
Mineral deficiencies will rarely occur in chickens that are free ranging and chickens that are fed a balanced ration.
If calcium deficiency in laying hens occurs, put crushed seashells or coral or limestone in a feed box in the corner of the chicken shed.
Protein deficiencies are common if there are no natural high protein grain or plants available.
The deficiencies cause a very slow growth rate of young chickens and sometimes death.
In older birds, the breastbone is very pronounced and the chickens are very thin.
Later the chicken becomes very lazy and weak, walks with great difficulty and will die.
Feed a high protein feed, such as meat meal, or poultry concentrate with the sweet potato or other energy type feed being fed.
Also, you can boil some fish and mix with the other feeds.
If soybeans, peanuts, mung beans and snake beans are available, mix these grains with the other feed.
10.2 Botulism or food poisoning
It usually occurs more with ducks than chickens.
It is caused by bacteria growing in stale wet feed that has gone putrid.
The chickens will sit down and extend their necks out as far as possible and will be very drowsy.
Death occurs in 1-4 days.
If the chickens are fed outside, thoroughly clean out feed troughs after every feeding.
Change the site of feeding regularly, so that the ground under the feed trough doesn't become saturated with feed.
There is no cure.
10.5 Fatty liver of laying hens
It occurs only to chickens confined to laying cages.
The chickens are confined to a small area and so get very little exercise.
High producing hybrid chickens are more prone to fatty liver than pure bred stock, e.g. Rhode Island Red.
There is very little that can be done for fatty liver as the first thing that the farmer knows about it is the chicken has died.
10.1 Baccillary white disease
Baccillary white disease, pullorum disease, is a contagious disease in young chickens, caused by the bacterium Salmonella pullorum.
The disease is often fatal and infected birds pass watery white faeces, stop eating and stand with their heads tucked and their wings hanging down.
The disease is transmitted to young chickens by infected hens through their eggs.
14.0 Profits, costs, returns
If people keep some village hens or modern hens so they can sell the eggs, then they must know if they have made a profit.
1. Costs
The two kinds of costs are establishment costs and production costs.
1.1 Establishment costs
These are costs you pay for things that will last for years.
It would not be a good idea to take all these costs away from the returns for one year.
Instead you can make a guess at how many years these things will last, say 5 years, and then divide the cost by 5 for working out one year's costs.
Establishment costs for egg project:
Costs of squared timber for cages $9.00
Cost of lock and key for door $1.10
Cost of oil drum for feeder $1.00
Total establishment costs = $11.10.
1.2 Production costs
These are costs that you must pay each year.
For example, each year you must pay for some Amprolium or other drug to stop coccidiosis.
Production costs for one year:
$9.40 for 500 grams of Sulfaquinoxiline drug (enough for 5 years) = $1.80
Twelve hybrid layer chickens at 70 cents each = $8.40
Freight costs = $2.00
25 kg. of chicken starter feed at $14 per 50 kg. = $7.00
Total production costs = $19.20.
2. Returns
This is the money received when you sell eggs in a market.
Always keep a record of the returns so you know how much money you have received.
Sold 27 dozen eggs at $1.10 per dozen = $29.70.
3. Profit
1. Total establishment costs / 5 = $11.10 / 5 = $2.22
2. Total production costs = $19.20
Total costs = $21.42
Profit = (Returns - Total costs)
Profit for first year = ($29.70 - $21.42) = $8.28
Working out profit in this way may indicate:
1. Profits increase more hens are bought and more eggs are sold.
2. No profit is possible if less than 200 eggs are sold.
10.6 Fowl cholera
Queensland researchers are using advanced genomics and bioinformatics technologies to help egg farmers better identify and protect against fowl cholera.
This highly-contagious disease, caused by the bacterium Pasteurella multocida, is particularly problematic in free range systems, where it progresses and spreads rapidly and can cause high mortalities of up to 20 per cent.
Prevention by using fowl cholera vaccines can be more effective than medicating birds once infected.
Currently vaccines for the disease are either a killed product (either off the shelf or specific for a farm) or a live vaccine.
For the killed vaccines, the critical component of the vaccine is the lipopolysaccharide (LPS) molecule component of the bacteria.
The complication for researchers and farmers is that the P. multocida bacteria causing fowl cholera has at least 16 known LPS molecules and, when used in a killed vaccine, these will only work when they identically match the strain causing the infection in the hen.
The University of Queensland (UQ) Alliance for Agriculture and Food Innovation (QAAFI) Postdoctoral Research Fellow Dr Lida Omaleki says even a small change in the LPS structure, such as removing a single sugar to create a different sub-type, renders the vaccine ineffective.
Previous industry research has found a molecular tool that can recognise eight genetic LPS types for this disease, but the key is to find the LPS sub-types to use in vaccines.
Dr Omaleki says the new project will use whole genome sequencing and bioinformatics analysis to create a better system for analysing whole genomes and the components linked to LPS type and LPS sub-type.
She says through an Australian Eggs and Agrifutures funded project, a team from UQ aims to be among the first in the world to develop a practical diagnostic technology for rapid and cost effective identification of the LPS type and/or sub-type affecting farms during an outbreak.
This will lead to choosing a more suitable strain(s) to be used in killed vaccines against fowl cholera.
“Our overriding goal is to be able to advise industry, especially egg farmers, on the best fowl cholera vaccine to use,” she says.
The UQ study includes a comprehensive set of 125 isolates of P. multocida bacteria derived from outbreaks of fowl cholera in an organic chicken meat flock and a free-range layer flock.
“Already we are seeing wide genetic variation, across time, in the fowl cholera challenge strains that are present on these farms, which clearly complicates selection of an appropriate and effective vaccine,” Dr Omaleki says.
“By better understanding the DNA sequences linked to the LPS sub-types, we hope to identify the best vaccine strain or strains for optimum disease protection.
“This should lead to better advice about what vaccines should be used, which field strains of bacteria should go into farm-specific vaccines and which strains should be removed from a farm-specific vaccine.”
Contact: Dr Lida Omaleki, Research Officer, QAAFI Centre for Animal Science, E. l.omaleki@uq.edu.au
Original article published: EGGSTRA! Egg Industry Matters
12.1 Receiving poultry supply and thawing
Poultry is supplied dressed or ready-to-cook, i.e. plucked and eviscerated (innards removed), and without head or feet.
Use fresh poultry as soon as possible or be held for not longer than 3 days in a refrigerator at 1oC.
Take care that poultry is not left out at room temperature when delivered.
Thaw frozen poultry at -1oC.
Remove it from the freezer 18 to 24 hours before it is required for food.
Thaw it in a refrigerator.
However, you can thaw it at room temperature for 6 hours, but not in warm water.
If the poultry has been wrapped in plastic, do not remove it before thawing, but remove poultry from shipping cartons and spread out for easier thawing.
Place the poultry on trays to catch the melt and use the birds within 24 hours.
Never re-freeze poultry so it can be eaten later.
Never buy partially-thawed poultry or fresh poultry that is "sticky".
Refrigerate eggs, use them within two weeks, cook them thoroughly, and never consume raw eggs.
12.2 Grading and packaging poultry
Poultry is usually sold by numbers related to the weight of the bird and rise in steps of 100 grams, e.g. No. 10 weighs 1 kg and No. 11 weighs 1.1 kg (1100 g).
The size of the bird chosen for eating depends on how it is to be used on the menu.
Larger birds have more meat in relation to the carcass than smaller birds, i.e. greater proportion of meat compared with the weight of the bones.
12.3 Poultry grades
Grade 1.
Roasting chickens, broilers, are the best quality chickens and are 7 to 9 weeks old.
The skin is unbroken and the birds are packed without feet or giblets.
Grade 2a.
Catering grade chickens are similar in quality and tenderness to roasting chickens, but the skin is broken during processing.
Broken wing tips and minor bruising to form small red patches may be seen.
Grade 2b.
Chicken pieces may be cut from the poultry and sold.
Pieces may also be cut from the best parts of birds that have broken bones or severe bruising during processing.
Pieces may be bone-in or boneless and may include all parts of the bird or as specified, i.e. chicken breast, chicken wings, chicken thighs (drumsticks).
Boiling fowls are:
* Layer hens weighing about 1.3 kg formerly used in egg production
* Meat breeder hens up to 65 weeks old and weighing 2 to 3 kg.
Boiling fowls are suitable for poaching and for dishes where only the flesh is required.
12.4 Poultry composition
The edible meat consists of muscle surrounded by connective tissues and fat deposits.
Bone supports this muscle structure.
The skin of poultry is edible, but some people are offended if served cooked poultry skin.
Poultry meat may be dark meat and light meat.
Chicken breasts from young birds have a higher niacin content than lean meat.
Dark meat is a better source of riboflavin and thiamine than white meat.
The differences in food value between dark meat and white meat are not important, but some people prefer to eat light or dark meat male or female poultry, particular parts of the carcass.
Poultry fat deposited on the muscle and under the skin makes the meat more tender and more juicy.
The fats improves meat flavour unless it is old poultry with excessive fat.
Older female birds have more fat and fuller breasts than males.
12.5 Poultry structure
Connective tissue surrounds the meat muscle fibre and holds it together.
Older birds and more active birds (village birds and roaming birds), have more connective tissue, and less tender meat.
However, some people prefer the taste of "free range" birds.
Breast meat has connective tissue than leg muscles so it cooks faster than the leg meat.
However, breast meat has less fat than leg meat and will become dry from long cooking, unless the moisture lost during cooking is replaced by basting, or using methods to retain moisture,
e.g. aluminium foil over the breast.
Limited exercise helps to fatten the birds and they become ready for eating at an earlier age.
They attain desirable market weights in a relatively short period of time and possess characteristically tender, fleshy muscles.
12.6 Preparation prior to cooking poultry
Ready to cook poultry should not require picking of pin-feathers, or similar types of cleaning.
Pin feathers are soft feather buds protruding from the skin.
When selecting meat birds for killing, leave chickens with pin feathers to be killed later. when the pin feathers have grown big enough to be plucked easily.
However, some breeds of chicken always have pin feathers at any mature age.
To inspect all poultry after thawing and remove any spongy red lung tissue inside the back, loose membranes, pin-feathers, and skin defects.
Remove these, inspect and rinse any necks and giblets wrapped and packed in the body cavity of chickens, turkeys and ducks.
Wash poultry inside and out under cold running water and leave to drain.
Chickens to be used for deep fat frying must be thoroughly dry.
Keep to a minimum, the time the cut parts are exposed to open air at room temperatures.
Refrigerate all cooked chicken that must be held for any time before serving.
12.7 Cooking poultry
Dry heat methods include pan frying and roasting.
If roasting, thoroughly cook poultry with low temperature.
Under-cooked poultry is very prone to attack from bacteria.
Thighs (drumsticks), require longer cooking than breasts.
While the thighs complete cooking, the breast and skin have a tendency to become dry.
Therefore, the technique known as basting is used in poultry cooking.
Basting adds moisture to the skin and breasts and facilitates the browning and roasting process.
Prepare thawed and cleaned chickens, turkeys and ducks for roasting by rubbing with salt and pepper.
Spread over the entire inner and outer surfaces.
Really excellent seasonings that are not cooked Inside the birds can be prepared.
Roasting with stuffing requires longer cooking periods.
Prior to roasting, poultry should be trussed by folding the wing tip under the wing stick and locking in place against the back of the bird.
Legs, too, must be secured in place.
Place birds into roasting pans and pour over melted dripping.
Do not pour melted dripping over ducks as these birds are rich in fat.
Baste frequently while cooking.
Cooking times and temperatures: 30 to 40 minutes per kg at 163oC.
Hot chicken soup is a folk medicine for the common cold.
It may increase the movement of mucus and generally soothe the patient, but it is not a specific cure for colds.
12.8 Quality points of poultry
* The breast of the bird should be plump.
* The vent end of the breast-bone must be pliable.
* The flesh should be firm.
* The skin to be white, unbroken and with a faint bluish tinge.
* Any blue discoloration with an attendant stickiness and smell is a sign of deterioration in quality.
Boiling fowls usually show marked signs of toughness, the end of the breast bone is firm and hard, and the skin shows an many long hairs before singeing.
The legs are covered with large shiny, hard scales.
12.9 Drawing a chicken
Singe the bird with a flame.
Make an incision down the length of the neck.
Pull out the windpipe and crop.
Cut the neck off close to the body, pulling the skin to one side and leaving a piece to fold over the back.
Place the bird on its back.
Enlarge the vent opening and remove the remaining organs and through this opening, i.e. the gizzard, intestines, heart and liver with the gall bladder attached to it.
Do not break the gall bladder.
Remove the lungs, the spongy masses lying between the ribs in the hollows of the backbone.
Take out the kidneys.
Open and clean the gizzard, heart, neck and liver in cold water.
12.10 Trussing a chicken
See diagram 50.13.1: Trussing a chicken
Trussing is often omitted when preparing poultry for cooking as the bird's shape is set to some extent during processing.
However, trussing is desirable as an aid to the presentation of whole birds and for poaching.
Cut off the first joint of the legs and press them down close to the sides of the chicken.
Fasten with a skewer or tie with string.
Secure the wings by running a skewer through the joint of one wing right through the body to the other wing,
or tie close to the body with fine string,
or fold wings underneath the back.
To truss a fowl for boiling, cut off the whole leg except for the thigh, the end bones of which tuck into the apron.
Tie the wings with string close to the body.
A trussing needle is not necessary if the following procedure is adopted.
1. Open the carcass at the vent and remove the fat adhering to the inside near the "parson's nose", (fleshy protuberance. uropygium).
Take out the neck (if any), and make sure the cavity is empty.
2. Open out the skin of the neck and remove the wishbone using the fingers and a small knife.
3. Fold the skin of the neck under and turn the wing tips underneath the bird to hold the neck skin in place.
4. Place the bird on the bench and press the legs down into the body.
5. Pass a string under the bird and cross the ends over bringing them out under the drumsticks so that the strings lie in the creases along the breast.
6. Turn the bird over and bring the strips up from under the wings.
7. Tie off the ends across the backbone.
7.1 When trussing by this method the knuckle joints should be left on but must be removed prior to serving.
7.2 Removal of the wishbone assists in carving the breast and also avoids the risk of small splinter bones if the bird is to be cut up.
12.11 Jointing a chicken
To joint a raw chicken slit the skin round the junction of leg and body and remove the legs.
Cut off the wings together with a piece of breast close to the joint.
Then cut the breast from the back and cut it in half lengthways through the bone.
If it is a large chicken, cut it in half again crossways.
Trim the back and cut in half.
Cut the legs again at the joint.
1. Remove the legs.
Place the chicken breast side up, pull one leg away from the body and cut through the skin between the body and the thigh, then cut between the ball and socket.
Bend the leg firmly outwards and cut through between the joint, thus giving the thigh and drumstick.
The leg may also be left in one piece, which is known as the Maryland.
Repeat this procedure with the other leg.
2. Remove the wings.
Press one wing against the body, making both parts of the shoulder joint visible beneath the skin.
Cut between the ball and socket of the joint, then pull the wing outwards and cut down through the skin at the base of the wing.
Repeat this procedure with the other wing.
3. Remove the breast from the carcass.
Place the blade of the knife inside the cavity and pierce one side between the shoulder joint and the rib cage.
Cut parallel to the backbone and through the rib cage.
Repeat this procedure on the other side.
Pull the breast away from the back to expose the shoulder bones.
Cut between the shoulder bones to detach the breast.
The back may be cut into two or left whole and used for making stock.
4. Cut the breast in half.
Place the breast skin side up and cut into two lengthways.
If the bird is large the breast may be cut again across the width yield 4 to 6 breast portions.
12.12 Chopping a chicken, Chinese style
1. Place the chicken, breast side up, on a wooden chopping board.
With a cleaver cut through the centre of the chicken, just to one side of the breast bone.
The chicken should now be divided Into two equal portions.
2. Take one side of the chicken, cut in half, between the thigh and wing section.
3. Remove wing, by pulling back and cutting through the joint, cut into two pieces.
4. Cut the breast section (after the wing has been removed), into three equal pieces.
5. Remove leg, by pulling back and cutting through the joint, cut into 3 equal pieces.
6. Cut the thigh section (after the leg has been removed), into 3 equal pieces.
7. Repeat with second side.
The chicken should now be cut into twenty-two pieces.
8. Chinese cooks cut the chicken in this manner for two reasons:
8.1 The chicken is cut into small pieces, which allows it to be eaten with chop sticks.
8.2. The chicken can be re-assembled into chicken shape on the serving platter.
12.13 Boning a whole chicken breast
See diagram 50.13.2: Boning a chicken breast
Lay chicken breast skin side down on a wooden board.
Using a sharp, short-bladed knife, cut into flesh close to outer edge of central breast bone, easing it away from the bone without cutting through the skin.
With the left hand, take a firm grip on outer end of breast bone, holding remaining breast with right hand.
Bend bone firmly until it snaps at the joint and carefully pull it out, working from joint end.
Remove remaining bones using one of the following methods:
1. Using the knife, and working from top to bottom, carefully cut away flesh from rib bones.
Insert point of knife into flesh at base of wishbone, cutting along either side of the bone until It can easily be removed.
Repeat with remaining bones.
2. Holding the breast with left hand, use the fingers of the right hand to ease ribs gently away from the flesh.
3. The remaining bones, except the wishbone, can be removed with the fingers by pulling on each bone with one hand and pushing the flesh away with the other.
Use a knife if the bone is difficult to remove at the joint end.
4. Cut along both sides of the wishbone, push flesh away to base, twist firmly and pull out.
12.14 Carving a chicken
Remove the legs by pressing them outwards and downwards and cutting them off.
Remove the wings by cutting down through the joints together with a portion of breast.
Cut the breast into several thin slices lengthways, leaving a piece of skin attached to each slice.
Divide a smaller bird into 4 pieces, the two legs and the halved breast and wings, without the back.
13.7 Enjoy eggs every day!
1. Eggs have a high nutrient density, because they provide top quality protein and a wide range of vitamins and minerals in proportion to their calorie count.
One large egg, 50 g, contains 310 kJ / 75 Kcal.
2. Egg protein quality is so high that scientists often use eggs as the standard by which they measure the protein quality of other foods.
Eggs add protein to the diet, as well as various other nutrients.
Eggs supply all the essential amino acids, vitamins and minerals, vitamin A, riboflavin, folic acid, vitamin B6, vitamin B12, choline, Fe, Ca, P, and K.
Eggs are one of the few foods that contain Vitamin D.
A large egg yolk contains about 250 kJ.
The egg white (albumen), contains about 60 kJ.
A large yolk contains more than two thirds of the recommended daily intake of 300 mg of cholesterol.
About 33% of the liquid weight of the egg is the yolk that contains all of the fat, about half the protein, and most of the other nutrients.
The yolk contains choline, about half the recommended daily intake.
3. One egg equals one ounce of lean meat, fish or poultry.
4. Besides protein, eggs also contain small to significant amounts of 13 vitamins and 13 minerals.
Eggs do not contain vitamin C, but serving eggs with orange juice, tomatoes or broccoli easily remedies this.
5. For most healthy people, an egg yolk a day is okay and will not increase risk of heart disease.
Apparently, there is no difference in relative heart disease risk, between those who ate less than one egg a week and those who ate more than one egg a day.
6. Research has found that dietary fat, especially saturated fat, is the real culprit in raising blood cholesterol levels.
The ratio of an egg's fat content equates closely with recommended ratio of a dietary fat intake: 2/3 mono and polyunsaturated fats and 1/3 third saturated fats.
For a 50 g large egg yolk
1.5 g (37.5%) = saturated fat
1.9 g (46%) = monounsaturated fats
0.68 g (16.5%) = polyunsaturated fats.
7. All of the fat and cholesterol of an egg are found in the yolk, including all of the egg's vitamins A, D and E, almost all of the vitamins B3 and B12, choline and folic acid, 93% of the
vitamin B6, 90% of the thiamine, 76% of the biotin, 73% of the inositol, 50% of the niacin, 42% of the riboflavin, 44% of the protein and substantialportions of the mineral content of the egg.
8. Eggs are one of the most versatile foods.
They can be used to make a soufflé rise and a custard set.
Also, they can be scrambled, fried, pickled, hard-boiled, soft-boiled, poached, cooked in the shell, baked and refrigerated.
The proteins in egg white (albumen), allow it to form foams and aerated dishes, e.g. meringues, angel food cakes.
Mechanical leavening agents includes whisking egg whites to make air foams for sponge cakes batters and meringues.
Egg white is 90% water and 10% proteins, hydrophilic and hydrophobic proteins.
Beating unfurls the proteins to form clumps to become networks around air bubbles.
However, oils as in the yolk, stop the amino acids intereacting so foam does not form.
Prolonged beating causes loss of water from the foam as the forces between the amino acids becomes stronger and the foam collapses.
Addition of lemon or cream of tartar lowers the pH and may stop the collapse of foam.
Egg yolks are an emulsifier and are used to enrich cakes, emulsify creamy sauces and thicken pie fillings.
Eggs can be eaten raw, as in Japanese sukiyaki dishes and the "Prairie Oyster" (one raw egg + Worcestershire sauce + pepper sauce) a supposed hangover cure.
However, raw eggs are not a suitable food for old people or pregnant women, because of the danger of Salmonella infection.
In general, raw eggs should be avoided as a food.
Egg yolks are one of the few foods that contain vitamin D, which enhances the work that calcium performs.
Egg yolks can provide about 6% of your daily requirement of folate, (vitamin B9).
10. Lutein, C40H56O2, xanthophyll pigment
Lutein and zeaxanthin, found in egg yolks and carrots and spinach, have been shown to protect against a serious age-related eye disease, macular degeneration.
Carotenoids may be better absorbed through egg yolks than through vegetables due to the fats present in egg yolks.
11. Egg shell colour is caused by pigment deposition during egg formation in the oviduct.
It can vary according to species and breed from the more common white or brown to pink or speckled blue-green.
Chicken breeds with white ear lobes lay white eggs.
Chickens with red ear lobes lay brown eggs.
There is no link between shell colour and nutritional value.
In the United States, chicken eggs are usually white.
In the United Kingdom, chicken eggs are usually light brown.
In other countries other colours of eggs may be preferred.
12. Cephalosporin resistance in humans may be caused by the use of the drug n poultry production.
13.10 Genetically modified organisms (GMOs), and chicken feed
Some raw materials that are incorporated into stock feed may have been derived from genetically modified plants or microbes.
These raw materials are indistinguishable from equivalent products that have come from not been genetically modified plants and do not affect the end product.
> Stock feed ingredients that may have been derived from genetically modified plants or microbes that could currently be in use are as follows:
1. Soybean meal and maize, imported from the USA
2. Cottonseed and cottonseed meal imported from the USA
3. Possibly some amino acids
4. Some feed enzymes
5. Vitamins.
Soon, canola and canola meal can probably be added to this list of GMO-derived stock feed ingredients.
In considering the GMO foods issue as a whole, it is important to recognize the difference between primary and secondary ingestion of GMO foods by humans.
Primary human ingestion occurs via direct consumption of GMO foods, for example GMO-derived soybeans or tofu, from GMO-derived soybeans.
Secondary human ingestion occurs via consumption of animal food products such as meat, eggs and milk from animals fed GMO-derived stock feed ingredients.
To date, community discussion and debate regarding consumption and labelling of GMO foods has centred largely around primary human ingestion.
Animals ingest millions of genes every day from all the food that they eat, but these genes are not incorporated in their own genetic make up.
13.5 Egg grades
1. The US Department of Agriculture egg grading uses the interior quality of the egg and the appearance and condition of the egg shell.
So eggs of any quality grade may differ in weight or size.
Grade AA and Grade A eggs are used for frying and poaching where appearance is important.
US Grade AA eggs have thick and firm whites, high and round yolks, almost free from defects, clean, unbroken shells.
US Grade A eggs are the same as Grade AA eggs, but the whites are "reasonably" firm.
This is the usual quality sold in shops.
US Grade B eggs have thinner whites and wider or flatter yolks.
Shells must be unbroken, but may show stains.
This quality is used to make liquid, frozen, and dried egg products and other products containing eggs.
As eggs age, carbon dioxide diffuses out through the shell and is replaced by air, increasing the pH of the egg white and destabilising links between albumin and lysozyme proteins, which dissolve to make the white runny, called "loose whites".
Older eggs are more buoyant, because air has replaced carbon dioxide.
2. The Haugh unit, HU, describes egg freshness, based on the thickness of the albumen (Raymond Haugh, 1937).
Note the temperature, weigh the egg and break the egg onto a flat plate.
Use a M-shaped tripod micrometer to measure the height of the albumen midway between the yolk and the edge of the albumen.
Compare the height with the weight of the egg to give a whole number score between 20 and 100.
Scores above 90 for excellent, 70 for acceptable, and reject eggs below 60.
In United States egg grades, AA grade eggs score 72 HU or higher, A grade, 60 - 72 HU, and B grade, lower than 60 HU.
The Haugh unit is a correlation between egg weight and the height of the thick albumen.
The cumbersome calculation is weighted for a 56.7g large size egg.
HU = 100 log(h-.01*5.6745(30w^.37-100) + 1.9)
h = observed height of the albumen in millimetres
w = weight of egg in grams.
3. In other countries, eggs can also be graded as coming from free range hens, hens in barns and hens in battery cages.
4. In common language, an "addled egg" is a rotten egg.
13.6 Egg sizes
1. USA
Extra Large (XL) > 64 g, 56 mL
Large (L) > 57 g, 46 mL
Medium (M) > 50 g, 43 mL
Small (S) > 43 g.
2. Europe
Very Large 73 g and over
Large 63-73 g
Medium 53-63 g
Small 53 g and under.
3. Australia
Jumbo 68 g
Extra Large 60 g
Large 52 g
Medium 43 g.
13.1 Boiled eggs
If boiled eggs that are difficult to peel are usually too fresh.
Fresh eggs have a lower pH, and this does not allow the shell to separate easily from the underlying albumen.
If overcooked, a greenish ring may appear around egg yolk from the iron and sulfur compounds in the egg or when there is excess iron in the water.
Although the green ring does not affect the taste of the egg, overcooking may harm the quality of the food protein.
If you chill the egg for a few minutes in cold water until the egg is completely cooled, the greenish ring does not form on the surface of the yolk.
To cook an egg from room temperature, 20oC, in boiling water, 100oC, to have a perfectly cooked, but soft yoke, cook a small egg 47 g, for 2.9.minutes, a medium egg, 57g, for 3.3 minutes and a
large egg, 67 g, for 3.7 minutes. Some cooks say that eggs taken from refrigerator will be difficult to peel if not rested to room temperature before putting in boiling water
Experiment
Boil an egg
Put two same size eggs in the same volume of water in same size saucepans.
Add 1 teaspoon of salt to one saucepan.
While heating the saucepans for four minutes for semi-firm yolks and hard whites, insert thermometers and compare the temperatures of the water.
If the cooking eggs are stirred clockwise the yolks are supposed to remain in the centre.
The differences in temperature are negligible.
After 4 minutes take out the eggs, open them and compare the taste and firmness of the contents.
However a cook advises: Place the pot on the stove and bring to a boil.
Cover the pot and remove from heat and let sit for 13 minutes.
Drain the eggs and immediately place in an ice bath to avoid green yolks until completely cooled.
The green colour of yolks is caused by iron in the yolk combining with the sulfur in the white of the egg.
The longer the egg is cooked the more likely a green ring is seen in the yolk from the formation of green-grey ferrous sulfide and hydrogen sulfide gas.
To test whether an egg is cooked spin the egg on its side on the table.
An uncooked egg wobbles when spun.
Some cooks add salt to the water to denature the protein and solidify any of the white that may leak from a crack in the egg shell so that the egg does not shoot out a streamer of white.
Very fresh eggs are more acidic and more difficult to peel.
13.12 Nutritional value of eggs
One large egg is 50 g.
Chicken egg, whole, hard-boiled Nutritional value per 100 g
Energy 150 kcal 650 kJ Carbohydrates 1.12 g Fat 10.6 g Protein 12.6 g
. Tryptophan 0.153 g Threonine 0.604 g Isoleucine 0.686 g Leucine 1.075 g Lysine 0.904 g Methionine 0.392 g Cystine 0.292 g Phenylalanine 0.668 g Tyrosine 0.513 g Valine 0.767 g
. Arginine 0.755 g Histidine 0.298 g Alanine 0.700 g Aspartic acid 1.264 g Glutamic acid 1.644 g Glycine 0.423 g Proline 0.501 g Serine 0.936 g
. Water 75 g
. Vitamin A equiv. 140 μg 16% Thiamine (Vitamin B1) 0.066 mg 5% Riboflavin (Vitamin B2) 0.5 mg 33% Pantothenic acid (B5) 1.4 mg 28% Folate (Vitamin B9) 44 μg 11%
. Calcium 50 mg 5% Iron 1.2 mg 10% Magnesium 10 mg 3% Phosphorus 172 mg 25% Potassium 126 mg 3% Zinc 1.0 mg 10% Choline 225 mg Cholesterol 424 mg For edible portion only.
Shell: 12%
Source: USDA, Queensland, Nutrient database.
13.2 Cholesterol and fat in eggs
Eggs contain a high level of cholesterol, which can be dangerous for people suffering from hypercholesterolemia and certain gene disorders.
Some studies have shown an increase in negative effects between Type II diabetes patients and excessive egg consumption.
People on a low cholesterol diet may need to reduce egg consumption.
However, recent research showed no correlation between consumption of 6 eggs per week and cardiovascular disease or strokes, except in diabetic patients.
13.3 Contamination by bacteria
Pathogenic bacteria, e.g. Salmonella enteritis, can contaminate eggs as they pass through the cloaca of the hen.
So the egg shell should not be contaminated with chicken faeces, but be washed with a sanitizing solution as soon as possible.
Although Salmonella infection is rarely caused by eating eggs, infections by Salmonella enteritis and Salmonella typhimurium may
occur if egg shells are broken by careless handling or if laid by unhealthy chickens.
13.4 Egg allergy
Infants may have an egg food allergy usually against egg whites (albumen) rather than egg yolks, but they usually grow out of it.
Adults may experience a food intolerance to egg whites.
13.9 Food labels, eggs
Foods containing eggs should have an allergen alert on the labels, e.g. for the wine industry in Australia:
"PRODUCED WITH THE AID OF EGG AND MILK PRODUCTS AND TRACES MAY REMAIN".
11.12 Unfertilized chicken egg
See diagram 50.6.10: Parts of an egg
Put a flat transparent dish on black paper.
Break open a hen's egg.
Note the yellow yolk and the clear part called the "white" of an egg because it turns white when cooked.
Find a small white patch on the yolk.
In the centre of this white patch, too small to see with the eyes, is the germinal disc, the blastoderm, a sheet of cells that becomes the embryo chicken.
The yolk is a food store, mainly protein and fat.
The yoke is enclosed in a yolk membrane.
The albumen, "egg white", is a solution of mainly the protein albumen.
It is a store of water and protein.
The chalaza is one of a pair of twisted cords of albumen at each end of the egg.
It supports the yolk centrally within the shell.
The shell membrane consists of two membranes that prevent evaporation of water.
At one end of the egg the two layers separate to form the air sac, that allows the baby chick to take its first breath before it breaks open the shell.
The shell is mainly spongy calcium carbonate.
11.1.0 Cardboard box incubator
See diagram 50.6.3.1: Simple electric incubator
Use a large and small cardboard box.
Cut one end from the small box.
Cut a 15 cm2 window in a side of the large box.
Cut a slit in the top of the smaller box and suspend an electric lamp in it by a long electric cord.
Put the small box inside the larger box and pack newspaper between them.
The open end of the small box must fit against the side of the large box with the window.
Put a thermometer in the box where it can be read through the glass window.
11.11 Styrofoam cool box incubator
See diagram 50.6.3.4: Electric incubator
Punch a hole in the side of a Styrofoam box to fit a 40-watt light bulb socket.
Be careful! The light bulb socket is an electrical and fire hazard.
Keep the incubator away from liquids or wet areas and out of direct sunlight.
Put aluminium foil on the bottom of the box.
Put a piece of wire mesh across the box.
Be careful! Use safety glasses and thick gloves when handling wire mesh.
Make air holes in the sides and in the lid of the incubator.
Also, make a hole in the Styrofoam for a thermometer.
Maintain a constant temperature of 38oC in the incubator for 21 days.
Use different sizes of light bulbs and change the lining newspaper to regulate the temperature.
Put a dish of water in the incubator to keep the relative humidity at 55%.
11.13 Warm brooder
See diagram 50.6.3.2: Warm brooder
See diagram 9.16: A. Correct height for feeders and drinkers, B. How to hold a chick
A hen sits on eggs keeps them warm.
When the chickens hatch, they huddle under the hen for warmth and protection.
If there is no mother hen, keep the chickens warm with a 100 watt bulb in a brooder.
Do not let the chickens touch the light bulb.
Reduce the temperature each week by 3oC from 37oC to 21oC.
Give the chickens food and clean water.
Use shallow dishes for the food and water.
Put sawdust or straw in the brooder to absorb droppings.
At first give the chickens a handful of chicken mash.
Add more food to the dish each day and always provide clean water.
Keep the brooder clean.
15.01 Killing chickens
1. Do not allow young children to witness the killing of chickens, especially hens.
Most young children will become stressed by the sight of killing, especially killing by the neck chop method.
Children may become friendly to certain hens, treat them as pets and give certain chickens pet names, e.g. 'Henny Penny".
2. If the teacher is not experienced in killing chickens, it should be done by an experienced farm worker.
3. After selecting the chicken to be killed, to make later evisceration easier, isolate it for 12-24 hours with water, but no food.
15.1 Killing by the neck chop method
See diagram 50.6.13.1: Neck chop method
Use a sharp axe or hatchet and a stable wooden chopping block.
Instructions for right-handed people.
With the left hand:
Hold the chicken around the feathers and tail and push down so that the neck is against the chopping block.
The chicken will push its head up against its body to keep its beak horizontal.
With the right hand.
Strike the neck with a firm, fast chop.
Keep hanging on to the feathers and legs to prevent reflex fluttering and to allow bleeding of the carcass without spattering.
If plucking without scalding, start plucking as soon as possible, before the feathers become set in the dead skin.
Pull out only a few feathers at a time to avoid pulling off skin.
Start with plucking the wings, then the legs, then the body.
Keep a bucket of water nearby to clean the hands.
Plucking by scalding requires dipping the carcass in water at about 50oC for about 30 seconds before plucking.
Remove pin feathers one by one with the thumb against a small knife.
15.2 Killing by neck dislocation
See diagram 50.6.13.2: Neck dislocation method
This method requires a strong person who can move the arms quickly.
Instruction for right-handed people.
Hold the legs with the left hand and use the heel of the palm of the right hand to cup the head.
The beak should push out between the first two fingers.
Stand up and hold the chicken at waist height diagonally across the body.
While firmly holding with the left hand, jerk the right hand down and pull the left hand up to separate the head and neck.
The click sound of dislocation may be heard.
15.3 Eviscerating the carcass
See diagram 50.6.13.3: Cutting the carcass
Cut off the head.
Invert the carcass and cut the skin from the base of the neck to the breastbone.
Cut out the crop, hang the carcass by the legs and cut around the cloaca to make a circular hole.
Cut from the cloaca to the beginning of the underside, before the bone, insert the hand and pull all the innards towards the rear.
Wash the carcass and cut off the legs.
16.0 Keeping chickens at home
Chickens are fantastic for teaching children about routine and responsibility, and how to care for animals.
In an urban residential area you may need a permit to keep chickens at home.
Roosters are not typically permitted in urban residential areas.
Fee ranging chickens can also help with pest control, because they search for beetles, grasshoppers, insects and grubs they eat.
While doing so, they will naturally scratch your soil and turn it over, potentially depositing manure at the same time.
If you have laying hens, you will also have access to regular, fresh eggs at home.
Both Australia’s national free range egg standard and the RSPCA chicken guidelines recommend a minimum space of 1m2 per chicken.
Sunshine is great for chickens and they need the vitamin D as one of their key nutrients to produce high quality eggs.
If it gets very hot in summer, make sure the chickens have some good shade available throughout the day.
Choosing or constructing a good chicken coop is essential.
Have a structure that helps the chickens carry out their natural behaviours.
Provide elevation so the chickens sleep above the ground.
Nesting boxes are very important.
Without them, you may find they lay on the ground, and then you will have floor eggs covered in manure.
Laying boxes that open to the outside, making it easy to collect your eggs without entering the coop.
Choosing your chickens
The popular breeds of chickens for backyard pets are ISA Browns and White Leghorns.
Have a few different breeds in your brood.
If you want around 20 to 25 eggs per week, you will need about four or five chickens in your backyard.
Each hen will lay four to five eggs per week, on average.
Hens that may live for quite a while longer than they are producing eggs.
Providing food and water for your chickens
An adult female chicken eats about 4 kg per month.
Of this, between 2kg to 3kg should be specially purchased layer feed, which provides a balanced and healthy diet for your chickens and 1kg to 2kg per month can be recycled food waste.
Within that food waste, there needs to be at least 50% vegetable or green waste, while the rest can be pasta, bread and other carbs.
Chickens will forage for their own insects and bugs.
You will need a reliable water source, which is topped up daily.
Automatic water top-ups are useful if you are going away for a few nights.
Common duckweed, Lemna aequinoctialis, is protein-rich, as well as containing essential nutrients including vitamin A and beta carotene, which gives the yolks their beautiful orange colour.
Keeping your chickens safe
Foxes and big lizards and snakes can also be a problem.
Keep your coop as clean as possible and making sure you collect any eggs that are laid daily and not attract pests.
Do not overfeed your chickens, and leave lots of food scraps lying around.
Chickens can suffer from a range of parasite and infectious diseases.
Backyard chickens have been linked to Salmonella infections.
Enjoy having chickens at home! Poaching
Poaching eggs is cooking by simmering in water
Unlike boiling, the water temperature is kept below boiling point.
Eggs are commonly poached.
16.3.8 Prepare egg recipes
1. Scrambled eggs
The white of an egg, the albumen, contains globular proteins called albumin proteins, which also carry substances in the human blood. The texture of egg yolk and egg white, albumen, is because of the dissolved globular proteins with outer electrical charges that attract water molecules and prevent other proteins from clumping them together.
However, when egg are heated, as in making scrambled eggs, the globular proteins unravel, denature, exposing the inner charges on the proteins causing the S-H groups on the amino acid cysteine to oxidize and form covalent disulfide bonds, disulfide bridges.
So the scrambled egg becomes hard and loses water.
2. An eggbeater forms foam better at room temperature than when chilled.
If beaten too much, the foam breaks and becomes liquid.
Add sugar and cream of tartar to stabilize the egg foam.
Add fat to cause the foam to collapse.
3. Heat the white albumen of an egg.
Observe how it turns from slimy watery white to chalk white in a firmly cooked egg.
The protein loses surrounding water and shrinks.
The reaction is irreversible.
You cannot dissolve the solid egg white in water.
4. Proteins can be denatured by heat or weak acid solutions that destroy the hydrogen bonds and cause tertiary proteins to uncoil, e.g. vinegar, acetic acid, can "cook" an egg white, albumen, without heat.
5. Egg in a cake mix
Use a cake recipe that requires use of one egg.
Use the same recipe for making four cakes, but with no egg, one egg, two eggs and three eggs.
Eat the four cakes and describe the taste and texture of each cake.
6. Make custard
Whisk together 2 egg yolks, 2tsp cornflour and 2tbsp sugar until well combined. Heat 1 cup of the milk and 1/2 tsp vanilla until warm, but not hot. Remove from the heat and add the milk to the egg mixture. Tip the mixture back into the warming saucepan and whisk constantly until boiling. Take off the heat and whisk until the custard is thick enough to coat the back of a spoon. If you cook custard at too high or too low a temperature it becomes either watery or curdled.
7. Mix oil and water then shake.
The oil and water separates and settles according to the different densities.
Add a surfactant and shake.
An emulsion forms.
If the surfactant is egg yolk, i.e. lecithin, the emulsion is salad dressing.
Beat the mixture hard to obtain small droplets so that the emulsion becomes mayonnaise.
8. Beat an egg yolk until it becomes thick.
Add lemon juice or vinegar.
Slowly add olive oil while stirring.
A stable emulsion forms.
9. Lemon juice does not dissolve fat, but lemon juice can hydrolyse tough fibres in meat to make it more tender.