Chick Processing

Chick Temperature

The chicks are now hatched and ready to be processed. But even a good hatch can still be spoiled. Hygiene, careful chick handling and attention to the chicks are essential for maintaining the best quality. The chicks tell you by their behaviour and noise if they feel good or not. If they do not, the problem should be investigated and solved.

Scientific trials as well as hatchery and brooding practise have shown, that the body temperature of a chick is one indicator for its well being. Occasionally measuring the rectal temperature of a representative sample of chicks can help to identify weak points in the process and by this contribute to safeguard chick quality. The rectal temperature of a day-old-chick measured by an infrared ear thermometer should be preferably in a range between 39.5 and 40 °C.

Checking the chick temperature directly after chick pull gives information about the conditions in the hatcher. This can be used to adapt the temperature profile if necessary for the next hatch. It is normal that the chick temperature drops temporarily during sexing and vaccination. After the processing is completed and the chicks stay in boxes in the holding room the body temperature should be back in the optimal range.

Chick Take-off and Sexing

All H&N International varieties on the commercial level are either colour or feather-sexable. If the breed allows for colour sexing, it is usually done directly at chick take-off, whereas the gender sorting of the other breeds is done as a second process. Those readers who are interested in getting more information about the sexing are referred to the appendix of this guide.

To achieve optimal conditions during takeoff one should consider the following recommendations.

  • There should be a separate chick take-off room to keep the fluff away from chick vaccination.
  • From a hygienic point of view taking out the chicks by hand is preferred to the use of a separator.
  • Do not pull too many trolleys at once. It is a common finding that chicks overheat when chick trolleys are waiting in an aisle or other holding areas with insufficient air movement.


Day-old-chick Vaccination

Chicks can be vaccinated in the hatchery by injection, spray or eye drop. Regardless of the route of administration there are three different factors that influence the success of the vaccination:

  • 1. Physical factors – needle damage/ chilling/ spray particle size
  • 2. Contamination
  • 3. Under/over dosage (inappropriate vaccine strain)

Every layer chick is vaccinated by injection against Marek’s disease. There are several vaccines from different producers available. Check requirements in your country.

The Mareks vaccine virus is cell-associated. That means that the virus is grown in tissue culture and the live cells are harvested and frozen in liquid nitrogen to be able to store them. The viability of these cells must be maintained throughout the preparation and injection to maintain the right vaccine titre. If the cells get killed because of wrong temperature or rough handling (squeezing through small needles) the titre will drop and the chicks will not get the necessary vaccination dosage.

Some practical guidelines are listed below:

  • There should be dedicated clothes for people working in the vaccine preparation room
  • Regular control of the nitrogen tank and record in a logbook is necessary
  • Do not take the entire can out of the tank
  • Expose only the ampoule(s) to be used
  • Thaw ampoules in 27 °C water bath by gently swirling
  • Best use distilled water in the bath (or clean fresh tap), change it daily
  • Once vaccine has become liquid, remove ampoule from the water bath
  • Use new sterile syringe with a new needle (18 Gauge)
  • Maximum of 5 – 6 ampoules should be prepared at a time
  • Dry ampoule before opening
  • Never refreeze thawed vaccine
  • Diluent should be clear, not cloudy
  • Gently draw up vaccine from the ampoule and add to the diluent bag
  • Complete process (thawing + adding to the diluent) in 90 sec or less
  • Gently swirl and invert the diluent bag several times
  • Record the time of preparation on diluent bag
  • Keep the ready prepared bags at a temperature of 15 – 25 °C

During the application of the vaccine it is important to:

  • Use sterile infusion kits.
  • Use the vaccine within 2 hours after preparation.
  • Not allow contaminated air to enter the vaccine bags. Use air inlet filters.
  • Keep the vaccination equipment clean throughout the hatch day.
  • Change needles frequently (every hour).

Beside the vaccination against Marek’s disease, often a spray vaccination against Infectious Bronchitis is done at the hatchery. Prior to use, the vaccine is dissolved in water, after which it expires within hours. Therefore it must be used immediately after preparation. The water serves as a transport medium for the live virus to the chicks.

  • Once sprayed the virus will attach to the mucosa cells of the chicks’ eyes and upper respiratory tract. The cleaning of the feathers with the beak will optimise the uptake.
  • When using spray vaccination it is important that the droplet size is not too small (at least 100 – 150 microns).
  • The spray must not look like a steam. Such small droplets will be inhaled too deeply, which can results in post-vaccination reactions.

When preparing the vaccine it is important that there is dedicated equipment only for this purpose. Any disinfectant present can kill the virus. Make sure that the water is of good quality (no chlorine, low mineral content) and that all the chicks are sprayed evenly.

Chick Holding and Transport

The behaviour of the chicks is the best indicator of the climate conditions during chick holding and transport. Under optimal conditions the chicks are mostly quiet, breathe calmly through the nostrils and are evenly spread within the boxes. If it is too hot the chicks will start panting, which leads to increased moisture loss and dehydration. If it is too cold the chicks will huddle together. Chilling is likely if wet chicks (pulled early, vaccinated by spray) are placed in a store with high air speed or too cold temperature.

In general an air temperature between the boxes of 25–27 °C (77–80 °F) and a relative humidity of 50–60 % is recommended. However not the room temperature, but the temperature inside of the boxes is crucial for the well being of the chicks. Usually it should be 33–35 °C (91–95 °F). So the optimal room temperature differs depending on the air movement in the room, the type of the boxes, the way of stacking and the number of chicks per box. In order to give the chicks a good rest the holding room should be kept dark. Light should be only provided if the chicks received feed.

It is a good practise to check the conditions during holding and transport with a data logger.

If the chicks are scheduled for a long journey they benefit from extra moisture, that can be given during vaccination without extra handling. When applying the injection subcutaneously the diluent volume can be increased to 0.5 ml. Of course the vaccine

dosage should stay the same. Therefore a different size of diluent bag has to be used. The volume for an intramuscular injection should not be bigger than 0.2 ml to avoid tissue damage.

Do the basics right

  • 1. Always pay attention to the behaviour of the chicks. It is the best indicator for their well being.
  • 2. Prepare the vaccine in a separate, clean room.
  • 3. Don’t allow unfiltered air to enter the vaccine bags or bottles.
  • 4. Keep the vaccination equipment clean throughout the hatch day. Change needles regularly.
  • 5. Temperature of the chick processing and holding room should be approximately 25 °C (77 °F).