WATT PoultryUSA - January 2018 - 27
still evident, suggesting this method
may not be perfect for welfare.
When using tunnel systems that
immerse birds directly into a readymixed single concentration of
gas, the birds should ideally reach
that gas concentration as soon as
possible, and ideally within 10
seconds to minimize the duration
of any discomfort from the CO2
Within sections of the gas machine where birds are conscious,
air humidity should be at least 60
percent to help reduce any negative effects of CO2 on birds' respiratory tract mucus membranes.
Temperature should be as close as
possible to ambient.
Visual and audio alarms must
be obvious enough to easily alert
staff when there is deviation from
program settings, and machines
can also be programmed to stop
loading when gas concentrations
are inappropriate for stunning.
Another type of controlled
atmosphere stunning has emerged
in recent years -- low atmosphere
pressure (LAPS) -- which performs
a slow, controlled decompression
that mimics ascent to high altitude.
LAPS appears to induce loss
of consciousness more slowly than
gas-induced stunning. Research
has shown that birds are unconscious before convulsions begin,
which is important from a welfare perspective. However, there
are some behaviors with LAPS
January 2018 ❙ www.WATTAgNet.com
that are indicative of respiratory
effect, such as open bill breathing and head shaking, but these
are no more than what would be
seen with anoxic or inert gases.
However, given that time to loss of
consciousness can be longer with
LAPS, wherever birds are experiencing these effects for longer
needs to be considered. ■
Visit us at IPPE, booth C3223