Egg shell quality

Egg shell quality

Good egg shell quality is very important for every layer farmer. Numerous factors affect the functional quality of the egg shell, mostly prior to the egg is laid. But also poor housing, high ambient temperature or rough handling of the eggs can affect the eggshell quality.
There are various reasons why egg shells can be weaker:
Bird strain
Check the strain of the birds you are using: Eggs with a dark brown egg shell have a higher shell quality than lighter brown or white eggs. Some strains of the birds may be able to deposit calcium for the egg shell at a faster rate than others, resulting in better deposition.  In the management guide from the strain you are using is displayed what the egg shell strength should be for this breed. For example: Optimum Novogen Brown egg shell strength is 40 Newton. To measure the shell strength of eggs, a meter can be used (image 1).

Image 1 - Egg shell strength meter (example from Futura)

Is there any sign of disease amongst your birds? Diseases like infectious bronchitis (IB), Newcastle disease (ND), avian influenza (AI), Mycoplasmosis and egg drop syndrome (EDS) affect the shell quality. IB virus causes soft/rough shelled eggs, discolouration and wrinkling of the shell, see image 2. EDS virus affects only the shell gland but with ND or IB, every portion of the reproductive tract can be affected. When birds are suffering from mycoplasmosis you will find eggs with a weak and glass-like top (image 3). You can check for diseases using ELISA tests in the blood of the birds. If the titer (the amount of antibodies in the bird) is elevated (more than the elevation caused by vaccination), the disease can be the cause of the bad egg shell quality. 


What is the ‘route’ for the egg from the chicken to the egg packing? Check the way your workers are handling the eggs, or if you have an automatic egg handling machine, check if there is no rough handling involved. This can be checked in the machine by using an electronic egg (image 4).


Age of the bird 
Older flocks lay larger eggs and the thickness of the shell usually declines. The hen is genetically capable of placing only a finite amount of calcium in the shell. Secondly, the hen looses some of her ability to mobilize calcium from the bone, and is less able to produce the needed calcium carbonate. The absorption and mobilization of calcium decreases to less than 50% of normal after 40 weeks of age. In older hens therefore, it can be useful to add extra calcium (Keprofoscal Oral) and vitamin D (Vitamin AD3E 50/20/20 Oral) to the drinking water. Read more about these products at the end of this newsletter. 

Administering drugs can have an influence on egg shell quality. For example, sulfa drugs affect the eggshell quality, whereas tetracyclines have some beneficial effects. 

The egg shell is formed by the activity of cells lying in the oviduct and uterus. Under stress, the secretions of these cells become acidic and the cells can be damaged or destroyed. In extreme cases, stress induced effects can result in eggshells that have excess deposits of calcium - a sort of powdery "flour" - on the surface and result in misshapen eggs (image 6). In times of stress, supplementation of calcium (Keprofoscal Oral) and vitamin D (Vitamin AD3E 50/20/20 Oral) can be useful.

Image 6 - Eggshell with excess deposits of calcium

Environmental temperature 
Egg shell quality is somewhat compromised during summer months. Temporary thinning of the egg shell may occur during periods of high ambient temperature (above 25ºC) since feed intake is reduced. The shells quickly regain normal thickness when temperatures are reduced and feed intake increases. In times of heat stress, supplementation of calcium (Keprofoscal Oral) and vitamin D (Vitamin AD3E 50/20/20 Oral) can be useful. Anti Stress Forte wsp can be added to the drinking water to increase the resistance to heat stress.

Water quality
The quality of the drinking water for your layers can have an adverse effect on eggshell quality. It has little effect on feed intake, egg production or egg weight. Read more about water quality in this previous newsletter.

Diagnosing and treatment
If you investigate the causes of bad egg shell quality on a farm, your investigation starts with ruling out the following possible causes: 

- Bird strain
- Diseases
- Rough egg handling
- The age of the bird 
- The use of drugs 
- Stress 
- High environmental temperature 
- Bad water quality

If you were able to rule out all of these possible causes, you can conclude that your egg shell problem is caused by the diet formulation. Please note that water quality can still have a negative effect on your egg shell quality if the water quality seems good, but has a negative saturation index. If you want to know more about this, please contact us.

Diet formulation
As described above, when all possible causes of egg shell problems can be ruled out, the problem lies in the diet formulation. Either a deficiency of Vitamin D3 or an excess or deficiency of calcium can be the cause. If you suspect this could be the case, it is important to investigate the feed of the birds, whether this contains enough vitamin D3, calcium and phosphorus. Layer...

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