2. DOC Vaccination
Spray vaccination is the preferred method for
administering respiratory vaccines, eg. for Newcastle
Disease (ND) or Infectious Bronchitis (IB), especially
when vaccinating birds for the first time.
3. Spray vaccination can be undertaken either in the
hatchery or immediately after reception at the farm,
while the chicks are still in boxes.
Vaccinating in the hatchery is generally considered
more effective, as the process is automated and
therefore more controlled than the hand-spraying
that tends to occur on the farm.
Hatchery automated methods include either the use
of a spray cabinet that is triggered each time a box of
chicks is placed inside, or a spray vaccinator
mounted over the conveyor line for chick boxes.
4. Vaccines suitable for spray delivery are live vaccines,
produced by growing the required virus in incubated
eggs or tissues cultures. After attenuation (=weakening),
the viruses are freeze-dried and appear as a pellet in a
glass vial containing 1,000 - 10,000 doses.
This allows the vaccines to be stored under controlled
conditions for several months until expiry date.
Prior to use, the vaccine is dissolved in water, after which
it expires within hours and therefore must be used
immediately. The water serves as a transport medium for
the live virus to the day-old-chicks. Once sprayed, the
vaccine will attach to the mucosa cells of the chicks’ eyes
and upper respiratory tract.
5. Preening (= cleaning feathers with beak) optimises
uptake. Once in the body, the virus will multiply inside
the mucosal cells, to develop good local immunity in the
respiratory tract.
When administering vaccines by this method, it is
important that the spray is ‘coarse’, ie. that droplets are
at least 100 - 150 microns in size. Any smaller and the
vaccine will be inhaled too deeply into the respiratory
tract, resulting in an excessive post-vaccination reaction.
This presents as mild disease symptoms in the flock 3- 5
days after vaccination - and will have a negative effect on
production.
6. Sexing of DOC
There are different methods for sexing in DOC
Instrument sexing
Vent sexing
Auto sexing
Color sexing
Feather sexing
7. Instrument sexing
Instrument sexing is done with an optical instrument
(Keeler Instrument). An optical tube is inserted into
the large intestine of chicks and the gonads observed
directly through the intestinal wall.
Male chicks have two testicles while females usually
have only one ovary which is located on the left side.
This method requires considerable training and can
result in injury to more chicks than does the vent
sexing method.
8. Vent sexing
Vent sexing was originally developed by the
Japanese and involves visual examination of the
cloaca of the chick with the sex being distinguished
according to minute anatomical differences.
This method requires extensive training over several
months for mastery, but is quite accurate and rapid
once considerable experience is gained.
9. Auto Sexing
Auto-sexing is the use of an easily observable sex-
linked characteristic to distinguish the sex of the
chick. Because there is a rather limited number of
sex-linked characteristics which can be used, and
these are present in only a few breeds of chickens, it
is necessary to utilize the carrier breeds or to
introduce the sex-linked gene into the desired breed
or strain.
10. It is important to note that in birds, the male has XX
and the female has XY sex chromosomes.
This is the opposite of mammals where the female is
XX and the male is XY. In sex-linked crosses, the
gene in question is carried on the X-chromosome.
11. Color Sexing
Another method for sexing DOC is color sexing
In broiler crosses, day-old female chicks are gold or
buff-colored while the male chicks are light yellow or
white.
12. Feather Sexing
In this case, the sex of the chick is determined
according to the length of the wing feathers
(primaries and secondaries) at hatching.
The males have relatively shorter wing feathers than
the females. In the female, the covert feathers are
always shorter than the primary feathers. In the
male, the covert feathers are always as long as, or
longer, than the primary feathers.
13.
14. Chick Transport
Specially designed vehicles must be used to control the
chicks’ environment throughout the journey from
hatchery to growing farm
The minimum ventilation rate needed to satisfy
adequate oxygen is 20 CFM (34 m3 /hr) per 1000
chicks during winter weather, and twice this amount
during hot weather.
The vehicle should be equipped with an auxiliary
heating system but may use fresh ambient air for
cooling.
If summer air temperatures exceed 86 °F (30 °C),
cooling equipment is required.
15. The vehicle cab should have a display showing the
temperature within the load to enable the driver to
adjust air vents for cooling.
Chicks should be held at an in-box temperature of
about 90 °F (32 °C) that can usually be achieved by
a vehicle air temperature of 75 °F (24 °C) with
plastic boxes or 71 °F (20 °C) with cardboard boxes.
16. Chicks delivered in plastic boxes require greater
care to prevent overheating or chilling than those
in cardboard.
Ensure the vehicle has adequate heating and
cooling to handle plastic boxes.
Boxes must be correctly stacked and spaced to
allow free air movement around them.
Each row of boxes should be locked with a bar
running the full width of the vehicle to prevent any
movement during the journey.
17. The vehicles can be provided with a rear plastic
curtain to help retain heat while chicks are being
unloaded.
Chick delivery drivers must be well trained and
conscientious. Each driver should start the day
with clean clothing and should change into fresh
coveralls/footwear for each delivery.
It is preferable for drivers not to enter the poultry
house.
18. Power wash delivery vehicles with
detergent/disinfectant on each return to the
hatchery.
Vehicles should carry a disinfectant spray so that the
wheels can be cleaned between farms if delivering to
more than one location in a day.
Chick boxes returning to the hatchery represent a
high health risk.
They must be kept separate and thoroughly washed
and disinfected before re-use.
