The older a hen gets the more likely there will be egg quality issues and fewer eggs laid; this is quite normal.
In the commercial world eggs must meet strict guidelines and grading to ensure eggs of only the highest quality reach the consumer. There are various organisations which monitor this and you may wish to have a look at www.britegg.co.uk. The shell reflects the bird’s harmony with its internal and external environment.
Egg shell colour will vary between breeds and generally the colour will be white, tinted, a shade of brown, blue or green. It may well be a good idea to check what colour your particular breed lay to avoid any concern regarding shell colour when they come into lay!
Firstly, it is important to have a system of knowing how old the eggs are from your birds; so marking with a date in pencil or storing in labelled boxes is a good idea to avoid eating old or stale eggs, or even worse giving them to someone else! A fresh egg should have no smell, a firm, round yolk and a thick white which appears raised if cracked onto a plate. As the egg ages the yolk absorbs the white and the white gets thin and runny. Eggs should be stored in a cool room around 10 degrees.
The eggs above show how there can be variation in size and shape when a pullet comes into lay; the 1st egg which is laid is often misshapen or very small, then as time goes on they generally become more uniform. Eggs are not necessarily laid every day, but a succession of eggs before the bird ceases laying for a time is called a clutch.
Common Problems
Cracks
Problem
Large cracks, hairline cracks, star cracks or holes which result in a broken shell membrane
Cause
- Incorrect nutrition – especially regarding vit D3 & Calcium.
- Infectious Bronchitis.
- Egg eating by the birds.
- High shed temperatures.
- Flock age.
Control
- Feed correct rations for age and class of bird.
- Give supplement of D3, as advised by vet.
- Follow an effective vaccination programme.
- Collect eggs frequently, use roll out trays to remove eggs as soon as laid.
- Give adequate ventilation.
- Replace aged birds with pullets if is an option.
Thin shelled or shell-less eggs
Problem
Eggs which are laid with no shell, just the membrane like an egg in a bag.
Cause
- Often laid by pullets coming into lay, particularly if matured early and the shell gland has not yet developed.
- Defective shell gland.
- Stress.
- Infectious Bronchitis.
Control
- Controlled feeding on approach to point of lay.
- Correct nutrition for age and class of bird.
- Cull birds which persistently produce such eggs as there is no cure.
- Reduce disturbances in poultry houses –good management.
- practices as eggs can be laid prematurely without the shell.
- Follow an effective vaccination programme.
Rough Shells
Problem
Shells with rough patches or areas, often which can be rubbed off. Common in early lay as a result of double ovulation, which produces one shell-less egg and another with extra shell deposits.
Cause
- Defective shell gland disturbances at time of lay can cause egg to be held over for another day.
- Diseases such as Infectious Bronchitis, Infectious Laryngotracheitis or Avian Encephalomyelitis.
- Lighting Pattern changes.
- Water depravation.
Control
- Reduce any stress to birds in or around the poultry house, or access by other livestock and vermin.
- Follow an effective vaccination programme.
- If using artificial light to prolong day length, ensure there are no sudden increases in day length as pullets come into lay or other sudden lighting changes during lay.
- Check daily that water is in place and drinkers are functioning properly.
Misshapen Eggs
Problem
Where shells differ from the normal smooth ovular shape; flat sides, lumps, wobbles etc. Common when pullets come into lay or with hens late in lay—mature birds.
Cause
- Immature shell gland.
- Defective shell gland.
- Infectious Bronchitis.
- Stress.
Control
- Controlled feeding on approach to point of lay, to offset sexual maturity by a couple of weeks.
- Cull birds which persistently lay such eggs, as there is no cure.
- Follow an effective vaccination programme.
- Reduce any stress such as overcrowding and disturbances in or around the poultry house.
Mottled or Glassy Shells
Problem
Parts of the shell appear translucent or glassy giving a mottled effect. Often thin shelled.
Cause
- Overcrowding.
- Disease.
- High Humidity in layer house.
Control
- Avoid overstocking of the poultry house.
- If possible ensure that the layer stock come from apparent stock vaccinated for Infectious Bursal Disease (Gumboro/IBD).
- Ensure good ventilation is implemented.
Stained Eggs
Problem
Shell is mottled or striped with blood or faeces.
Cause
- Blood from prolapsed cloaca, cannibalism or vent pecking.
- Blood spots or stripes.
- Faecal contamination.
Control
- Avoid getting pullets too fat as they have difficulty laying the egg as the incidence of prolapsed will therefore increase.
- Red mite infestation. As the egg is laid into the nest box the red mites get squashed and therefore leave deposits on the shell surface.
- Keep nest boxes clean, collect eggs frequently, use roll away nest boxes. Loose droppings will cause contamination, ensure birds are not producing them due to a feed imbalance or an enteric problem.