Cages for laying hens are an essential element in poultry facilities to ensure their profitability. They must comply with the standards established to maintain animal welfare and optimize production parameters.

In poultry production, laying hens are especially important since the eggs has become an important food worldwide. According to FAO data, egg production grew 152% between 1983 and 2013. In other words, in 1983, 29,3 tons were produced and in 2013, 73,8 tons. Regarding the type of export, it was recognized that 83% is made up of whole eggs of hens, 14% as liquid egg and 3% as dehydrated egg.

The previous data highlight the importance of egg in world nutrition. For this reason, the poultry sector, and specifically laying hens, has investigated and developed housing systems that guarantee the welfare of the birds while maintaining production parameters.

In this article we will detail the most important aspects of laying hens cages, reviewing topics such as their importance, density of birds per cage and characteristics.

Importance of the facilities in the welfare of laying hens

Facilities of any poultry production must fulfill two fundamental functions: to allow a suitable organization of the flock and to provide a friendly environment that allows optimal performance while guaranteeing animal welfare.

Laying hen cages have evolved throughout the history of poultry farming. Currently, there are smart cages for chickens that allow obtaining various parameters of the shed through sensors. This system measures and registers important variables for any poultry farm such as 1) temperature, whose variation has a rapid and direct impact on the behavior, performance and welfare of the birds; 2) ammonia levels, which are a key guide and tool when monitoring shed moisture and population density; 3) wind speed and light, which are environmental factors that can affect birds; among other variables that can be measured. If this system is not available for the farmer, the same variables can be registered with the conventional methods separately.

It is extremely important to keep a record of the mentioned parameters since they may have an impact on the poultry farm. These parameters must be evaluated both from the point of view of veterinary medicine (health and comfort effects) and zootechnics (effects on production and behavior). Its constant review by both professional fields is key in the prevention, monitoring, and solution of problems generated by alterations in temperature, ammonia levels, or environmental elements (light, heat, humidity, wind).

In addition, cages for laying birds must be complemented with welfare measures such as:

• Access to a healthy and nutritious diet based on the zootechnical recommendation that will be reflected in the egg quality (size and weight, yolk color, nutrients).
• Appropriate and friendly environmental design that promotes comfort.
• Permanent and responsible care of the animals. Staff must be trained.
• Handling, transport, and slaughter should be done according to ethical and legal considerations in all its stages.
• Balanced environmental conditions that avoid problems such as heat stress, strong winds, or excessive humidity.
• Daily cleaning of fecal matter and food waste collection systems.
• Control of insects (disease vectors) and rodents and wild birds (disease reservoirs).

How should the cages for laying hens be?

The cages for laying hens must have certain specific characteristics. Some basic ones are:

• Egg-producing hens must have an available area of ​​450 cm² inside the cage to guarantee their comfort and movement.
• Chicken cages must have a feeder that can be available at all times to provide adequate feeding. Channel-type feeders are recommended, which must provide a space of 10 linear cm for each bird housed in the cage.
• Chicken cages must guarantee the birds a supply of clean and available water. The use of automatic drinkers that lead to two nozzles per cage is recommended; Another alternative is to use 10 linear cm containers for each bird housed.
• Battery cages for chickens should have an ideal height of 40 cm, this height should be present in 65% of the total cage.
• The floor of chicken cages should be strong enough to safely support each leg. Its inclination should not exceed 8 degrees, otherwise, it will cause discomfort to the birds, by generating slips when they want to move or stand. Cage floors are regularly made of materials such as:
  • 14-gauge welded wire
  • Perforated paper sheets
  • Plastic: used alone or as wire covering.
• The floor of the cages should be of a grid size that is large enough to allow the free fall of feces through the holes. At the same time, the grid of the floor should prevent the legs of the hens from coming out or getting caught in them. Their status should be checked frequently to avoid foot injuries that generate infections and thus cause a drop in egg production.

The density of chicken cages: essential

Birds, like other homeothermic animals, produce heat, humidity, and carbon dioxide as a product of their metabolic processes. These factors have a direct impact when deciding the population density, that is, how many birds we will keep in each cage.

An article by Nicodemus et al. of 2012 mentions several studies on the ideal density in production birds. Most of them point out that a low density (4 hens per cage) has had better results in terms of the number of eggs produced and their weight. Other studies obtained better results with high densities (5 birds per cage), but they associate it with external conditions such as nutrition, genetics, and others. However, the stress generated by the lack of space can lead to behaviors such as cannibalism or pecking among birds. In addition, animal welfare guidelines of most countries recommend reducing the density to guarantee more freedom of movement for the birds housed there.

Thus, we must understand that managing a good population density will bring benefits such as the following:

• Less cannibalism and harmful feather pecking among laying hens: birds in comfort will not have pecking behaviors among themselves
• Good thermoregulation: an adequate density will avoid high temperatures in the birds that generate stress and affect egg production.
• Access to water and food: if the number of birds per cage is ideal, they will be able to freely consume water and food, which is essential for optimal posture.
• Better yields in egg production and egg weight in some geographical areas (take into account other aspects such as nutrition, genetics, etc.).

Is it advisable to use cages for laying hens?

The use of laying cages for commercial egg production has become popular for its efficiency. However, we must recognize that they may have advantages and disadvantages that we will detail below:

Among its benefits we can mention:

• Birds are less exposed to environmental pollutants and circulating infectious pathogens.
• The eggs do not come into contact with the chickens or their feces avoiding their waste by pecking and their contamination.
• There are no predation problems for laying hens
• Food waste is reduced.
• The problem of dampness in soft litters, which has veterinary repercussions on birds (irritation of mucous membranes), is avoided.
• Nesting behavior is avoided.
• The appearance of fractures produced in the flight of birds from medium heights or by traumatic landings are avoided.
• Eggs from hens in a cage have the same amount of fat and protein as eggs from hens in other housing systems.

Among its disadvantages we can list:

• Initial investment in the purchase of batteries and their adequacy
• Poor management of the population density of birds, which can be penalized.
• Manure management can be a problem.
• Hens housed in cages lay fewer eggs than hens that are on the floor.
• Investment per hen is usually higher than in flat production.
• There is a slightly higher percentage of blood spots on the eggs.
• Eggs from free-range chickens have higher levels of fatty acids and vitamins

At present, there are various types of cages for laying hens, with variations in their size, type of floor, and arrangement of the grids that compose them. Cage systems are categorized according to density. There are cage systems with only one bird, with multiple birds (3 or 4), and colonial cages that house between 20 and 30 hens.

The arrangement of chicken cages will help us to conserve and use space more efficiently and reduce investment in the house.

This has led to the following general classification of cage arrangement:

• Single-floor: has a row of cages; it is simple and practical in temperate climates in open houses.
• Double-decked – Popular because the upper deck is balanced and allows evacuations to fall through the wire mesh of the house floor without touching the bottom floor of the cage. This system is also referred to as a “ladder rung”.
• Triple or Quadruple Story: To further conserve space, use three or four stories.
• Flat floor: although they are simple cage installations, they are placed together without a service corridor. The type of handling is employing an automatic narrow channel that moves back and forth over the cages.

Conclusions

Chicken eggs are one of the most important sources of animal protein worldwide, due to its low price and high nutritional value. The increase in the demand for food has led animal production to be more efficient in its processes. Regarding poultry housing, the laying hen cage system has been the most important lately and it is necessary to know it to guarantee the welfare of the laying hens housed.

REFERENCES:

• FAO, 2013. El huevo en cifras. Disponible online en: http://www.fao.org/assets/infographics/FAO-Infographic-egg-facts-es.pdf
• Nicodemus, N., Callejo, A., Blanco, D., & Buxadé, C. (2012). Efecto de la densidad de gallinas por jaula y de la estirpe sobre la producción y la calidad del huevo. Proc. V Reunión Anual de la Asociación de Especialistas Avícolas del Centro de México (AECACEM), 391-406.
• Taylor Preciado, A., Taylor Preciado, J. D. J., De la Rosa Figueroa, A., & Olmedo Sánchez, J. A. (2018). Conceptos básicos del bienestar animal en aves.
• SAG (2018). Guía de Buenas Prácticas sobre Bienestar Animal en los diferentes Sistemas de Producción de Huevos.1ª edición. Ministerio de Agricultura. Servicio Agrícola y Ganadero. Santiago de Chile. 48p. Disponible online en: https://www.sag.gob.cl/sites/default/files/gbp-ba_produccion_huevos_oct-2018.pdf
• Nicol, C. J., & Davies, A. (2013). Bienestar de las aves de corral en los países en desarrollo. Revisión del desarrollo agrícola. Organización de las Naciones Unidas para la Alimentación y la Agricultura(FAO). Disponible en: http://www.fao.org/3/al720s/al720s00.pdf

*Article expanded by Jerson Andrés Cuéllar Sáenz