Technological features of keeping laying hens in battery cages

Cage battery designs for laying hens

The choice of cage battery design determines the stocking density of the poultry and the overall efficiency of the poultry house utilization. Single-tier batteries facilitate mechanization and allow one worker to tend to more birds, but they utilize the room space inefficiently. To increase the efficiency of production facilities, poultry farmers use multi-tier designs of cage batteries.

The two-tier four-row automatic poultry line APL-2G consists of two paired single-tier batteries located one above the other. A manure floor is installed between the tiers, from where manure is removed by mechanical scrapers. Such a scheme allows for an average of 24–28 hens per 1 m² of the poultry house area.

The three-tier two-row K-21 battery has a length of up to 54 m. It is equipped with a chain feeder, nipple drinkers, and a scraper system for manure removal. The size of each cage is 400 x 500 mm; it is designed for four hens, and the egg collection on this line is performed manually.

Three-tier stepped batteries from "Big Dutchman" and "Diamond International" companies provide a high stocking density — up to 30 hens per 1 m² of the poultry house. The design is equipped with inclined manure floors on the second and third tiers, from which manure is cleaned by scrapers into the lower channel. This allows for reducing the width of the batteries and leaving narrow service aisles no more than 70 cm wide between them.

Depending on the cage size, it can house from three to nine layers. The equipment is supplied with chain feeders, nipple, cup, or trough drinkers, and eggs are collected by a conveyor made of jute or plastic belt. Stepped batteries are suitable for large industrial scales: they are used, for example, to equip poultry farms in the Moscow region with 300 thousand layers.

Growing technology and stocking rates for chicks

During the first two months of life, chicks grow very intensively, after which their development rate decreases significantly. In the first weeks of rearing, thermoregulation in young birds is still imperfect, so they are critically demanding of the temperature regime. To obtain good results, it is necessary to strictly observe the stocking density and the feeder space requirements. Overcrowding leads to growth retardation and mortality, while an excess of free space reduces the economic efficiency of the poultry house.

• Initial chick weight — 36–38 g
• Weight at the age of 2 months — 570–650 g
• Weight increase during the first 2 months — 15 times
• Weight of a replacement pullet at 5 months — 1400–1450 g
• Weight increase from 2 to 5 months — 2–2.5 times

When designing new facilities or re-equipping existing poultry houses, it is important to accurately calculate the cage area. Below are the standard parameters for stocking density and feeder space for young laying breeds by age periods. These data help to balance housing conditions and maintain the flock.

When rearing chicks in universal cages designed for long periods of housing (1–60 or 1–140 days), the density rate is taken according to the longest age interval. Accordingly, one should be guided by the indicators for the 31–60 or 61–140 day periods. This approach prevents overcrowding of birds as they grow.

Day-old chicks are sorted, preventing the placement of young birds that differ significantly in size and general condition in the same cage. If chicks are reared in multi-tier cages, the smaller and weaker ones are usually placed in the upper tier cages, where it is warmer and lighter. Chicks are also sorted when transferred from one age-group cage to another, for example from KBE-1 to KBM-2. However, it must be remembered that although sorting evens out groups of chicks in cages, which positively affects their subsequent condition, moving chicks to different conditions has an adverse effect on them. Therefore, rearing young birds in universal cage batteries has advantages compared to using age-specific cages that require frequent bird transfers. When comparing the two methods of rearing young birds (with transfers and without transfers), conducted at a poultry farm in the Moscow region, the following results were obtained: the yield of conditioned pullets when rearing with transfers was 85.9%, without transfers 92.7–93.7%; the cost of 1000 pullets was 2466 and 2226–2258 rubles, respectively. In addition, age-based bird transfers require significant labor costs.

Air temperature and humidity. If chicks are raised in heated cages, the air temperature is measured both in the cages and in the room; when using unheated cages, the temperature is measured in the middle of the room using a thermometer mounted at the level of the middle tier of the cage battery. For control purposes, it is desirable to have thermometers also at the beginning and at the end of the room.

The temperature inside unheated cages with chicks is approximately 2° higher than in the room.

Table 36. Air temperature for cage rearing of young poultry Air temperature (°C) Age of chicks (days) when reared in heated cages | when reared in unheated cages, in the room in the cage in the room 1—5 30—29 25—23 28—26 6—10 28—26 25—23 26—24 11—20 26—24 23—22 24—22 21—30 24—22 22—20 22—20 31—40 22—20 20—18 20—18 41 and more 20—18 18—16 18—16

It is necessary to monitor the air temperature not only by thermometer readings but also by the behavior of the chicks themselves. At an excessively high temperature, chicks drink a lot of water, crowd at the outer walls of the cages, and eat feed poorly. At an insufficiently high temperature, chicks chirp loudly and usually huddle in the back of the cage. At a normal temperature, the young birds, after feeding, settle down to rest evenly across the entire area of the cage. It should be remembered that sudden temperature fluctuations, both towards increase and decrease, are especially dangerous for poultry.

Air humidity during the first 15—20 days of the chicks' life is maintained within 65—70%, and subsequently, it is reduced to 55—60%. Humidity is regulated by means of a ventilation system; in case of insufficient humidity, as a last resort, spraying the floor in the room with warm water is permitted.

Lighting regime. The components of the lighting regime are the light source, illuminance, and the duration of lighting. The duration of lighting has the greatest influence on the development of young birds, which is obviously due to its natural regular changes and the dependence of poultry reproductive cycles on changes in the natural day length.

Illuminance, or light intensity, can vary within significant limits without having a substantial influence on the bird, which corresponds to large and irregular fluctuations of it in nature. For example, while in the shade of trees, a bird experiences an illuminance of several tens of lux; having stepped out into a sunlit space, it enters conditions of illuminance equal to several hundred and even thousands of lux. However, in cage housing, when the bird does not have the opportunity to choose a zone of optimal illuminance, the level of illuminance should be taken into account when regulating the lighting regime.

Changes in the duration of lighting, or the photoperiod, have a regular effect on young birds: an increasing or long photoperiod stimulates sexual maturation, while a decreasing or short photoperiod inhibits it. At the same time, a photoperiod increasing to a certain limit, for example, up to 18—20 hours, stimulates the sexual development of poultry to a greater extent than a stable photoperiod of that same duration (18—20 hours). Similarly, a photoperiod decreasing to 6—8 hours inhibits the sexual development of poultry more than a short, but stable photoperiod.

Excessively early sexual development of replacement pullets is undesirable, as it entails lower egg production, small eggs, especially in the first months of laying, and increased culling of layers. Therefore, it is recommended to raise chicks under a short stable photoperiod of 6—8 hours. In the first week of rearing, the photoperiod should be longer, namely: first week — 15 hours, second — 12, third week — 9 hours, and further until the bird is 5 months old — 6—8 hours. Such a gradual reduction in the duration of lighting is necessary so that all chicks get used to the housing conditions and the location of feeders and drinkers in the cages.

The specified lighting regime can be provided at any time of the year and in any geographic zone only in windowless buildings. If cage rearing of chicks in rooms with windows is necessary, lighting regimes are used that are compiled taking into account the month of hatching and the geographic latitude of the area. When compiling lighting regimes, the following conditions are followed: 1) increasing lighting duration during the chick rearing period must not be allowed; 2) the initial photoperiod for day-old chicks should be 8—12 hours longer than the photoperiod at the end of rearing; 3) the duration of lighting at the end of rearing should correspond to the natural day length at that time of year. It should be kept in mind that the second of these requirements cannot be fully met in some months and in some zones. For example, the end of rearing for chicks hatched at the latitude of the Moscow region in January falls in June with a day length of 17.5 hours. By taking the maximum initial lighting duration for day-old chicks as 24 hours, we get a difference between the final and initial photoperiod of only 6.5 hours.

When developing lighting regimens for poultry in buildings with windows, one should strive to make maximum use of natural light to save on electricity. When raising chicks hatched between May and August, supplemental electrical lighting may be unnecessary after just a few weeks, as the young poultry are raised under the natural decrease in day length.

At some poultry farms and in windowless buildings, a regimen of gradually decreasing daylight hours is used for chicks. At the Zhigulevskaya poultry farm in the Kuibyshev region, the daylight hours during the rearing period of young poultry are gradually reduced from 22 to 8 hours, and at the Noginsk poultry farm in the Moscow region, from 18 to 9 hours. Foreign companies producing hybrid young poultry recommend a short, stable light duration (6–8 hours) for some crosses, and a gradual reduction of daylight hours for others. Switching electrical lighting on and off in poultry houses should be done automatically using special devices (2-RVM, UPUS-1 apparatus, etc.).

It is necessary to remember that the lighting regimen during the rearing of replacement pullets has a very significant impact on their subsequent productivity. Errors made in regulating the lighting regimen during the pullet rearing period may prove to be irreparable during the egg-laying period.

Care of young poultry. Daily care of young poultry consists of a careful inspection of the birds and the removal of weak chicks. If the necessary culling and mortality of young poultry exceed the maximum permissible limits, it is necessary to determine the causes and notify veterinary staff accordingly.

To monitor the growth and development of young poultry, so-called control cages are set aside in each work area. The chicks in these cages are periodically weighed, the state of their juvenile molt is determined, and the obtained data are compared with standard values. At some poultry farms, zootechnical laboratories assess the condition of young poultry in more detail and conduct a monthly slaughter of several chicks that are average in development and live mass, determining the mass of their reproductive organs, vitamin A content in the liver, hematological indicators, etc.

Table 37. Live mass and molting status of egg-breed pullets

Age of bird (days) Live mass (g) Number of replaced primary feathers || Age of bird (days) Live mass (g) Number of replaced primary feathers 1 36—38 — 80 800—850 5.5—6.0 10 75—90 — 90 900—950 6.5—7.5 20 125—160 — 100 1000—1050 7.5— 7.8 30 210—260 0.5—0.6 110 1100—1150 8.0—8.3 40 320—370 1.5—1.7 120 1175—1225 8.5—8.8 50 440—500 2.5—2.8 130 1250—1300 9.0—9.2 60 570—650 3.5—4.0 140 1325—1375 9.3—9.4 70 700—750 4.5—5.0 150 1400—1450 9.5—9.6

Planning for rearing young poultry. The head count of young poultry to be accepted at day-old age for rearing is generally calculated based on 1000 5-month-old hens intended for flock replenishment. In doing so, the permissible mortality and culling of young poultry during the rearing process are taken into account. To transfer 1000 hens to the adult flock, one must accept approximately 1370 day-old pullets or 2740 unsexed chicks for rearing.

Table 38. Estimated calculation of the yield of 1000 replacement pullets for industrial hen flock replenishment

Rearing period (days) Indicators 1—30 | 31-60 | 61-150 | 1-150 Initial headcount 1370 1275 1150 1370 Mortality: % 2 2 1.5 5 head 27 25 18 70 Viability, % 98 98 98.5 95 Culling: % 5 8 11.5 22 head 68 100 132 300 Headcount at end of period 1275 1150 1000 1000

When these standards are followed, the yield of marketable pullets is 73% of the number of day-old pullets.