Hatchery and Hatchery Hygiene

PAGE 11

Hatchery and Hatchery Hygiene

S. T. MOUBARAK

The most important goal of all hatcheries is the production of high numbers of good quality chicks. Maximum production of the best quality chicks depends on five main factors:

1-Quality eggs.

2-Careful handling of eggs.

3- Precise incubation.

4- Correct chick handling.

5-Efficient management of the operation from collection of eggs on the farm to despatch of chicks from the hatchery.

Hatchery design and construction

Points to consider when planning a new hatchery:

1-Location of the breeder farm supplying the eggs and the growing farm which receive the chicks.

2-Access via roads, rail and even air (exporting chicks)

3- The cost of the land on which the hatchery will be built.

4-The availability of labour for the hatchery.

5-Provision of electrical and water services.6- Means by which hatchery waste can be safely and effectively disposed.

7- The likely incidence of poultry diseases in the local area.

8- Possible expansion of the hatchery in the future.

Hatchery Size and Location:Modem hatcheries are designed with many variables to consider such as building costs, equipment costs and access but the primary concern should be the movement of eggs and chicks through the building. There should be a positive flow of eggs, people and air from the "clean" to the "dirty" areas. Fresh eggs should not come into contact with chicks or hatch debris.

In locating a new hatchery, a balance has to be struck between the access to good roads, disease risk from other poultry, availability of labour and proximity of breeder and grower farms. A hatchery should be designed to permit a work flow which avoids cross contamination by ensuring that eggs, people and air all move in the same direction. The hatchery should be situated at least 150 m from poultry houses and the hatchery area should be considered a separate unit with its own entrance and exit.

Determining the size of the hatchery:

The size of the hatchery can be estimated in various ways:

- Egg capacity of the incubators.-Number of eggs that can be set each week or each setting.

-Number of chicks that can be hatched each week or each setting.

There are two systems for hatching eggs:

1- Single stage system. 2- Multistage system.

Single stage system (single stage setters)

The setters contain eggs of only one age. Setters are loaded with one batch of eggs which are all removed at transfer. Hence, the name "All in - All out". To get the best from single stage setters the set point temperature has to change with the developmental age of the eggs. At the start of incubation eggs need a higher temperature than they do near the end of incubation. In addition, the humidity setting can be changed to match the porosity characteristics of individual batches of eggs.

Advantages of single stage incubation:

1-Ease of operation.

2- Variety of different capacity machines.

3- Ability to change temperature and humidity settings to match the requirements of the eggs.

4- Best possible hygiene status, cross contamination reduced to minimum.

5- Better chances to maximize hatchability and chick quality from "problem eggs" e.g. eggs from a flock near the end of lay.

Disadvantages of single stage incubation:

1- The cost of machines is relatively high compared with multistage setters (except when large machines are used).

2- Management of single stage machines is more critical and errors can have severe effects compared with multistage machines.

Multistage system (multistage setters):

Multistage incubation involves having eggs of different developmental stages in the same incubator. Hence, eggs that are freshly laid are placed in a machine with eggs that have been incubated for a number of days. Three, four, six or eight stages can be present within the same machine depending upon the bird concerned. There is only one set point temperature and one humidity setting for all of the eggs in the machine.

Advantages of multi-stage incubation:

1- Ease of operation.

2- Relatively low cost for large capacity machines.

3- Using trolley-based setters with a central passage there is access for cleaning and sanitation.

4- Trolley-based setters allow easy and quick setting of eggs.

Disadvantages of multi-stage incubation:

1- Unlike multistage trolley systems, fixed-rack setters are very difficult to keep clean and are labour intensive to operate.2- Temperature settings are set as an average for all eggs irrespective of origin or age.

Example of multistage system:

3 setters + 1 hatcher

Capacity of setter = 38400 eggs

Capacity of hatcher = 19200 chicks i.e. 1/2 capacity of the setter.

Eggs are incubated in the setter until 18 days then transferred to the hatcher. Every 3 days let in 19200 eggs.

Hatchery floors:

1- It is essential that the floor area below and adjacent to the machine be as smooth and level as possible to ensure ease of drainage and efficient operation of the machines.

2- Floors should be smooth and hardwearing to allow easy movement of trolleys and dollies for a long period of time.

3- Floors should be sealed with an epoxy resin type product so as to be resistant to sanitizing chemicals and to prevent occurrence of cracks which will then harbour dirt and microbial contamination.

4- The run off to floor drains should be unobstructed avoiding areas where water can collect.

5-1% overall floor slope is required for easy flow to the drains.

6- Floor drains should be easy to clean and of sufficient size (at least 15 cm wide and 15 cm deep) to take maximum possible run off of water.Hatchery Work Flow:

As with eggs and chicks, movement of people through the hatchery should be from "clean" egg areas to "dirty" egg areas and not vice versa.

Preferably, corridors should be present which allow people to bypass rooms if necessary. Workflow must be monitored and controlled. The use of one-way doors assures a one-way flow of traffic. Hatchery employees should not be allowed to walk freely from one work area to another without taking proper sanitation precautions. A simple example of hatchery workflow is given below:

Hatchery Work Flow

Egg Receiving Area

Egg Holding Area

Egg Cooler

Setters

Hatcher RoomTray ' Wash Room

Tray Dumping

Chick Processing Area

Chick Holding Area

Chick Loading Area

The environmental requirements of the different hatchery rooms

RoomAir Temp. CRelative Humidity %Fresh Air IntakeVentilation Requirement.

Egg store15-1875

Exhaust air from machines must be ducted from the room and excessfresh supplied air must pass freely through to exhaust duct.

Setter Room24 - 28*

600.14 cm\m per1000 chicken eggs or 750 turkey or duck eggs or40 ostrich eggs.

TransferRoom24 - 28*600.34 cm\m per 1000 chicken eggs or 750turkey or duck eggs or 40 ostrich eggs.

HatcherRoom24 - 28*600.28 cm\m per 1000 chicken eggs or 750

turkey or duck eggs or 40 ostrich eggs.Exhaust air from machines must be ducted from the room and excess fresh supplied air must pass freely through to exhaust duct.

Chick take-off andloadingroom24 - 28*60-700.34 cm\m per 1000chicks or 750 turkey poults or ducklings eggs or 40 ostrich chicks.

*24-26 C in tropical countries, 26-28 C in temperate countries.Structure of the egg:

Composition of the ideal egg:

By weight: 12 % shell and shell membranes.

32 % yolk.

56 % albumen.

Which eggs should be considered cull eggs?

1-Cracked eggs.

2- Improperly washed eggs.

3- Misshapen eggs with shells which have ridges, spiral grooves, flat sides or sandpaper like surfaces.

4- Mottled appearance.

5- Rough or chalky shells.

6- Floor and other heavily contaminated eggs.

7- Very small or very large eggs.How is an egg formed?

1- The female sex cell (ovum) on the yolk is fertilized in the top of oviduct.

2- The yolk moves down.

3- In the infundibulum, layers of albumen proteins are deposited on the yolk surface.

4- In the magnum, the shell membranes are laid down on top of the albumen.

5- In the shell gland, the calcium carbonate layer of the shell is deposited and the egg expands due to water and salts being pumped into the albumen proteins which swell.

6- The complete egg waits in the vagina before being expelled through the cloaca.

Events before egg laving:

1- Fertilization of the ovum by the sperm.

2- Division and growth of cells.

3- Organization of cell types into groups (gastrulation).

4- When the egg is laid the embryo is composed of 60 000 cells.

Hatching egg testing and its significance: See practical course.

Factors affecting hatchability and hygienic requirements of

successful hatchery practice:

Hatchability:

1- The number of chicks hatched as a percentage of all eggs set.

2- The number of chicks hatched as a percentage of fertile eggs set.

The factors may be discussed under two main groups:

A- Environmental control (In setters and hatchers):

- Temperature.

- Relative humidity.

- Aeration.

- Egg storage, position and turning.

B- Other (non- environmental control) factors:

- Fertility.

- Sex of chicks.

- Maternal diet and health.

- Weather.

Non environmental control factors:

1- Fertility:

Fertility is the result of laying (breeder house) management i.e. healthy and normal breeder males and females.

Fertility is determined by "egg candling" after few days of incubation and this is called the crude method. True fertility can be only determined by egg breaking.

Both fertility and hatchability are influenced by hereditary factors.2-Sex of chicks:

It is impossible to predetermine sex before the egg hatches.

Sex ratio: ratio of males to females.

Primary sex ratio: at the time of fertilization : nearly equal.

Secondary sex ratio: at the time of hatching, is influenced by many factors e.g. genetic, lethal factors, time of egg laying (production, time of the day, season) for example, greater numbers of males are produced in hot weather.

3- Maternal diet and Health:

How does maternal diet or health affect egg quality?

1- Poor maternal diet can cause an imbalance of proteins, fats and vitamins in the yolk and albumen reducing embryonic viability.

2- Poor breeder diet can cause poor eggshell quality, which can reduce hatchability.

3- Diseases of the laying birds (e.g. ND and IB) can lead to poor quality of the egg contents and shell.

4- Infection of the oviduct can lead to direct infection of the yolk or albumen.

5- Weather:

Continuous days of hot or cold weather cause drop in hatchability.Environmental control (In setters, hatchers and during transfer):

A- Environment of the setter:

The followoing should be considered:

- Temperature

- Relative humidity

- Adequate ventilation and gas change

- Egg turning

1- Temperature:

Temperature determines the metabolic rate of the developing embryo.

-Temperature is adjusted to 37.5 - 37.7 C.

- In single stage, the temperature is slightly higher at the beginning of the incubation and then decreased gradually to 37.1C at the time of transfer (to avoid overheating of the embryos near the end of incubation).

What are the results of too high a temperature?

1- Death of the embryo.

2- Reduction in viability, so the embryo cannot develop and hatch normally.

3- Adverse effects on the normal absorption of the yolk contents.

4- Excessive drying of the egg contents during hatching.

5- Chicks with short down, pale-legs and poor pigmentation.

6- Small chicks with unhealed navels which have a delayed hatch even though some chicks hatched early.7- Embryos are usually killed by short periods of high temperature (39 C and above) and will not regain normal rate of development when returned to normal temperature.

What are the results of too low temperature?1- Low hatchability associated with delayed hatches.

2- Slow embryonic development.

3- Embryos are not usually killed by short periods of low temperature and can regain normal rate of development when returned to normal temperatures.

Does the egg temperature remain the same during incubation?

1- From setting to transfer the egg shows an increase in temperature such that it can be 1.5 - 2 C higher than that of the surronding air.

2- The additional heat is produced by the embryo's metabolism.

How can overheating of embryos near the end of incubation period be prevented?

1- Excellent ventilation allows the highest amount of heat exchange with the air.

2- Good cooling systems of the setters to remove heat from the air.

3- In multi-stage setters, cool eggs can be located next to old, warm eggs.

4- In single stage incubators the set point can be reduced. .

2-Relative humidity:

During incubation, the egg content must evaporate at a specific rate. A weight loss of 11 -12 % of initial egg to transfer mass (i.e. 1 - 9 days) is recommended for most bird eggs. This water loss is regulated through the following:

1- The egg shell has numerous pores which allow the diffusion of gases in and out of the egg.

2- The number and length of the pores determine the porosity of the shell.3- The relative humidity outside of the egg works in conjunction with shell porosity to regulate loss of water vapour.

4- For a given shell porosity the higher the ambient humidity the lower the weight loss will be.

Humidity inside setters is adjusted to 60 % through the use of humidifiers to raise the humidity of the incoming air (40 - 45 %). What is the result of too high a humidity in the setter?

1- Insufficient weight loss.

2- The small air space and excessive water result in the embryo not being able to orientate itself in the egg.

3- The volume of the air space may not be sufficient to allow the proper expansion of the lungs and airsac to initiate normal breathing.4- Malpositions because the embryo is unable to move its head under the wing.

5- Malabsorption of the albumen leading to sticky chicks.

6- Retention of free fluid in the egg near hatching.

What the result of too low a humidity in the setter?

1- High water loss and dehydration of the eggs.

2- Small chicks with short down and lack of pigment.

3- Adequate ventilation and gas change:

Importance of ventilation:

1- Oxygen supply for the developing embryo.

2- Removal of carbon dioxide.

3- Removal of extra humidity.

4- Removal of extra heat from the machines.

What are the proper levels for oxygen and carbon dioxide in incubators:

1- Oxygen is difficult and expensive to measure accurately, so CO2 is usually measured in incubators.

2- High CO2 levels indicate low oxygen levels.

3- CO2 levels in the setters should be between 0.1% and 0.4 %.

4-Above 1% C02 is too high and indicates poor ventilation.

Fresh air requirements: 0.14 cm\m\ 1000 hatching eggs .........

4- Egg turning:

Hatching eggs should be set large end up because the air cell invariably forms at the blunt end of the egg and the embryo always orientates itself to the top of the egg. If the egg is upside down in the setting tray, the chick's head will be away from the air space. Some chicks can hatch from the small end of the egg but most invariably die.

The importance of egg turning:

1- To prevent the adhesion of the embryonic membranes to the shell membranes.

2- To maximise growth of the extra-embryonic membranes.

3- To maximise formation of extra-embryonic fluids, especially the transfer of water from the albumen to the subembryonic fluid.

4- To ensure embryo access to albumen proteins.

In the setter, eggs in trays are automatically turned (tilting) by 45 once\hour. B- Transfer process:

The process of transferring hatching eggs from setters on day 18 to the hatchers. Eggs are removed from setting trays and placed flat (to permit pipping) in the hatcher trays (baskets). This process must be carried out as quick and smooth as possible to minimize egg cooling.

C- Hatcher environment:

1- Temperature:

From 36.1 -37.2 C (usually 0.5 C lower than the setter).

2- Relative Humidity:

In the hatcher relative humidity is adjusted to 70 % i.e. higher than the setter.

Why is humidity kept high in the hatcher?

1- During the hatching process the shell is broken which exposes the shell membranes to the air. If the ambient humidity is low then the membranes can dry out too quickly and effectively trap the hatching chick in the egg.

2- High humidity in the hatcher prevents dehydration of the chick during hatching.

3- High humidity helps to keep those chicks which have already hatched in good condition.

3- Ventilation:

- Carbon dioxide level: around 0.5 %.

- Fresh air requirements: 0.23 - 0.28 cm\m\1000 eggs.