The practical basics for a good shell quality

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Industry(ies): Laying Hens

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The economic performance of a laying hen farm is linked to many criteria: production, liveability, feed efficiency and the number of marketable eggs. For all egg producers, maximising the number of marketable eggs throughout the production cycle is essential. The quality of the shell is therefore a determining factor in the economic success of a flock of laying hens. There are several important points to consider in order to maintain a good shell quality until the end of the flock:


It is recognised that a quality pullet subject to light stimulation, i.e. at standard weight and in a homogeneous flock, is a determining factor in achieving a :

  • good laying peak,
  • high persistency,
  • but also good shell quality

This starting point is to be observed in order to optimise the performance of your batch. The brooding period is therefore the best time to invest in the future. By around 7-8 weeks, the chicks have already developed their structure as future layers, as such, early weight gains are essential. Indeed, a weight shortfall in the first few weeks impairs production performance. Most of the bone structure, muscles and organs are completed by 8 weeks of age.

Graph: Pullet growth development

If regular weekly growth is not ensured, there is the risk of an excessive accumulation of body fat and insufficient muscle mass and organs. It is recommended to concentrate on increasing the pullet’s body weight before 7-8 weeks of age to favour a good-quality layer right until the end of the flock.

Flock uniformity should also be measured, with a target of over 80%. A high uniformity favours a high laying peak and persistency as well as a good uniformity in the egg weight. (More information can be found in our article: Essential points to obtain a good layer pullet).


Once the pullets are ready to lay, it is possible to perform light stimulation. It should not take place at too low bodyweight, otherwise it will reduce the egg weight and also the quality of the shell at the end of the laying period. Effective stimulation involves increasing daylight length by at least 3 hours over a short period of 3 weeks.


It is important to optimise calcium intake to minimise the mobilisation of calcium from the medullary bone. The risk would be to tire the laying hen more rapidly at the end of the cycle. This must be supported by providing enough carbonate. In general, the coarse/fine carbonate distribution is approximately 60/40 in brown hens and 50/50 in white for a calcium intake of around 4 g minimum / hen / day. The feed should be chiefly ingested in the afternoon and just before night-time to promote good nocturnal calcification.

Graph. : Egg calcification process in laying hens

It is important not to wait for the quality of the shell deteriorate to act, because for some hens, it will be too late. Decreasing phosphorus often improves shell quality because it competes with calcium for absorption. It is possible to start gradually lowering it from 40 weeks. It also optimises feed costs. At the same time, add more calcium. With age, egg size naturally increase so there is more shell to be created. From 4 g per hen per day, this can be increased up to 4.5 g at the end of the laying period.


Manual or automatic intake of additional calcium, 1 to 2 g / hen / day in the afternoon improves shell quality in older hens. Marine origin shells are a good source of coarse calcium provided this raw material has good sanitary levels.


End-of-laying additives intended for shell quality can compensate for shortages occurring during the flock. This solution is often more expensive than investing in “basic” nutrients such as calcium, so it has to be timed properly. It is a last resort curative solution.


All flocks of laying hens have the potential to achieve good shell quality. Barring major incidents, such as a vitamin D deficiency for example, egg quality is easily maintained until mid of production. Then, flock fatigue, correlated to its aging, inevitably affects the quality of the shell.

It is possible to mitigate this aging-related effect, provided good management has been implemented before measuring its effects. Prevention is always more cost-effective than the cure. Investments in “basic” nutrients such as calcium, phosphorus and pullet feed can directly improve shell quality. It is also important to optimise feed consumption in relation to amount ingested and distribution times. Layer flock management and nutrition must work together to allow expression of the genetic potential and thus achieve the best performance.

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