Eggshell disorders can be a recurrent problem in poultry farms

Eggs are currently one of the most widely consumed foods in the world thanks to their multiple benefits. On the one hand, it is considered one of the most nutritious food products available. Secondly, it is the most accessible and economical animal protein in many countries. Third, it is one of the most important sources of direct and indirect employment in developing countries and contributes to world food security.

To meet the high demand for eggs in the food market, poultry producers and farms have been researching and implementing improvements of all kinds for decades. Among these developments, perhaps the two most important are related to genetic selection and poultry nutrition. In addition, these two have a close relationship with intestinal welfare and disease prevention in poultry.

Among the diseases affecting poultry production, there are infectious and non-infectious causes. Some of these can directly affect egg production, especially the eggshell. These shell alterations are a consequence of the disease processes that the poultry face. However, these signs also help to determine a diagnostic of a pathology that may be affecting a poultry farm.

Eggshell formation

Laying hens start egg production around week 20 of the production cycle. At this time, their reproductive system has matured sufficiently to start producing eggs.

Several physiological, hormonal, and metabolic processes are involved in the egg formation process. Shell formation is the last stage of this process and occurs in the uterus or eggshell gland. In this portion of the reproductive system, minerals that will form the eggshell are fixed.

The eggshell formation process is the most time-consuming stage of egg development. It takes 20 hours approximately. In the uterus, the egg begins to be coated by a calcium carbonate structure that precipitates to form the shell.

Importance of intestinal welfare in eggshell formation

The eggshell formation is a process that includes calcium homeostasis as a key factor. This mineral is the main mineral deposited in the shell formation process in the form of calcium carbonate. Therefore, poultry must obtain calcium from different sources.

One of the sources of calcium for shell formation comes from the bird’s bones. This source of the mineral is utilized thanks to hormones such as a parathyroid hormone. However, it is not entirely beneficial for this to be the main source as it could lead to bone decalcification.

The second source of calcium in poultry is obtained through the feed. During the production stage in laying hens, it is advisable to supplement with calcium sources. However, the physiology of the digestive system must be working properly to ensure the absorption of this mineral. Therefore, intestinal welfare plays a key role in regulating calcium levels that will become eggshells.

Finally, renal elimination of calcium also plays a key role. The kidney is one of the main organs regulating homeostasis in poultry, including minerals such as calcium.

Factors affecting shell quality

In addition to the direct causes that affect eggshells such as diseases, other factors must be considered in these disorders.

1. Older hens: older hens in the final stage of production may have a higher incidence of fragile eggshells because the egg is larger and shell mineralization is less efficient.
2. Juvenile poultry: in this age group, eggs can be produced as fragile because the eggshell mineralization process is not yet fully efficient.
3. Animal welfare: high levels of stress affect multiple metabolic systems and processes, including those that regulate the egg formation and laying process. In poultry with low animal welfare standards, fragile eggs, predisposition to eggshell breakage, egg retention, hypercalcified eggs, dirty or blood-stained eggs can occur.
4. Feed: the levels of amino acids and minerals supplied in the diet should supplement the needs of laying poultry. Proper egg and shell formation depend largely on the poultry’s nutrition. Under conditions of inadequate nutrition, weak eggs with thin shells can be found.

Infectious diseases causing eggshell disorders

Among the causes of eggshell, disorders are infectious pathogens that have multiple clinical signs. These diseases can affect specific organs but can also cause disturbances in the laying process.

1. Avian infectious bronchitis: Avian coronavirus is one of the main infectious causes of eggshell disorders. The course of the disease is usually severe and acute, including mainly respiratory signs. However, weak, wrinkled, and deformed eggshells are also a classic effect.
2. Mycoplasmosis: this bacterial disease is caused by Mycobacterium gallisepticum. This pathology has respiratory and digestive signs and causes alterations in the eggshell. As a result, the eggs may be weak, broken, or in farrowing.
3. Laryngotracheitis: this viral disease usually has a mainly respiratory course that leads animals to high morbidity. It also generates shell alterations such as weak, broken, or farrowed eggs.
4. Newcastle disease: this viral disease causes the eggs of this poultry to be weak or cracked and thin-shelled.
5. Egg drop syndrome: this pathology is caused by an adenovirus that generates a significant reduction in egg-laying. In addition, the shells are soft and may break.

Main eggshell disorders

Cracked or broken eggs

Eggs of this type can arise from stressful processes such as excessive heat, nutritional mineral deficiencies, excess salts in water, or fungal infections.

Eggs without shells

The eggs of this type of disorder don’t have a shell, instead, they are only covered by the outer membrane. The causes are multiple and include calcium and other mineral deficiencies, mycotoxins, or stress.

Irregular eggs

Egg shapes can vary markedly in symmetry or size. They may have these shapes due to immaturity of the uterus or viral infectious diseases.

Asymmetrical or lumpy eggs

Eggs that rupture during their formation are repaired by the poultry’s reproductive system by re-depositing calcium to cover the crack. As a result, lumps are noticed on the eggshell. This is associated with poor management of poultry house lighting or overcrowding stress.

Wrinkled eggs

These eggs have a thin shell that generates wrinkles. This is a product of double ovulation, and the shell formation is disturbed. This process is associated with oversized eggs, viral diseases, the use of antibiotics, or excess calcium.

Depigmented shell

The shell can suffer depigmentation due to multiple causes: poor nutrition, internal parasites, drugs such as Nicarbazin or tetracyclines, age of the poultry, among others.

Prevention strategies for shell disorders

To face all the causes that generate eggshell disorders and prevent eggshell damage, there are multiple alternatives. These options can improve the welfare of the poultry from several perspectives to obtain high-quality eggs.

1. Feed supplements: supplements with minerals and vitamins such as Alquerfeed Ovoponedoras allow improving eggshell quality in layers. This product have positive effect in conditions of heat stress or situations of insufficient calcium absorption since it prevents bone demineralization in laying hens.
2. Intestinal conditioner and optimizer pronutrients: the product Alquernat Nebsui, which contains intestinal conditioners pronutrients, is ideal to promote enterocyte regeneration in laying hens. This improves nutrient absorption and optimizes the digestive processes essential for egg formation. In addition, Alquernat Nebsui can replace antibiotic growth promoters.
   On the other hand, Alquernat Zycox contains pronutrients that optimize the intestinal mucosa and enhances the local immune system. Thanks to this, the poultry’s immunity improves to prevent pathological processes such as those caused by coccidiosis and avoids mucosal damage. Therefore, it allows replacing coccidiostats such as Nicarbazin.

3. Vaccination programs: Sanitary immunization programs are an excellent tool to prevent the impact of infectious diseases that affect poultry houses.
4. Biosecurity: Good biosecurity practices are a key factor in reducing the incidence of pathologies in layer farms.
5. Good practices: management plays an important role in the prevention of processes such as overcrowding stress or heat stress, which avoids alterations in the eggshell.

Conclusions

Egg production is one of the most developed industries in the livestock sector in the world today. Therefore, multiple advances have been made to improve the efficiency of laying hens. However, in the egg formation process, there can be problems that alter the eggshell.

The shell is a fundamental part of the egg for its protection. It is the stage that takes more time to complete in the bird’s reproductive tract. To achieve this, the poultry’s intestinal welfare needs to allow a correct shell formation. However, some factors can affect its quality. In addition, this process can be affected by pathogens.

For these reasons, it is necessary to consider prevention strategies for shell disorders. These include the use of feed supplements, administration of intestinal conditioner and optimizer pronutrients, improved sanitary and biosecurity programs, as well as improved management.

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