Poultry International - February 2018 - 32
32 ❙ PoultryInternational
HOW BROILER PHYSIOLOGY IMPACTS POULTRY YIELDS
ditioning to remove the build-up of heat and prevent birds
from dying from heat stress.
While at the birds are held in this area, it should be
possible to see whether there has been an adequate feed
withdrawal. This can be judged simply by looking for residues of mucosa or subintestinal mucosa that will have a red
appearance. Should this be evident, the receiving area supervisor can inform the head of evisceration, who will then
know the risk of fecal or feed contamination will be higher.
Taking proper account of broiler
physiology can help to ensure
maximum output of Grade A
the feeders and
drinkers in their panic to escape. Skin may also become
scratched. Should birds become particularly stressed, then
the fragile bones of the thorax may break.
All of the above can lead to carcasses being rejected at
the processing plant.
The head should be first part of the broiler to come into
contact with electricity if the stun is to be effective. If wings
or the breast touch the dampened ramp leading to the water
bath, they will receive an electric shock. The broiler will
struggle and lift its head and this may lead to it not entering
the water and the bird not being stunned. This will have an
impact on slaughter and bleed out, or the bird may enter the
scalder still alive.
Birds must be captured with care. Broilers should be
firmly held with their wings pressed to the body to prevent
flapping, but not so firmly as to impede breathing.
Care must also be taken as they are placed into crates,
to minimize aggression from birds that have already been
If stacked trays are used, they should be filled from the
top down to avoid harming animals as they are put into the
metal framework. If filled from the bottom upwards, the
risks of birds being knocked increases.
It is common that two different sizes and weights of
broilers are processed within a single shift. To accommodate this, the height of the water bath can be adjusted, along
with the voltage and amperage.
However, despite such adjustments, at times even if a
new batch of birds has the same average weight as the preceding batch, birds may enter the bleed tunnel with their
When this occurs, the exit from the last plucker should
be checked to see whether the birds in the batch had full
crops. Chickens do not have diaphragms and, for this reason, when hung by the legs, should the feed withdrawal
period have been too short, feed will pass back through
the esophagus, placing pressure on the trachea and making breathing difficult. It is this sensation of drowning that
cause the birds to move their body and wings. ■
Once birds are caged or in containers, the temperature
within the container will rise. This temperature will rise
further still once the crates are loaded onto the trucks, and
if the trailer is not properly ventilated or air-conditioned,
the birds will suffocate.
At the processing plant
The receiving area should also have adequate air con-
Eduardo Cervantes López is an international consultant
based in Colombia. He can be contacted at icproave@
hotmail.com or via www.icproave.com.
www.WATTAgNet.com ❙ February 2018