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Humane Transport of Broilers in Western Canada
Hank Classen and Tennille Knezacek
Department of Animal and Poultry Science
University of Saskatchewan
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ABSTRACT/SUMMARY
Pre-slaughter management of broiler chickens under Western Canadian
climatic conditions was studied, with emphasis on the transportation
of broilers from farm to slaughtering plant. Data collection included
evaluation of the barn environment and bird condition prior to loading,
temperature and relative humidity on the trailer during transport,
death during the trip, and bird condition upon arrival at the slaughtering
plant. A total of 31 trips were monitored over an ambient temperature
range of -27.2°C to 21.9°C
INTRODUCTION
Managing the last day of a broilerís life is a major challenge
to the broiler industry. It involves feed and water withdrawal,
catching, vehicular transportation to the slaughtering plant, lairage
before slaughter, shackling and finally killing. The overall impact
on broilers is dependent on the cumulative effects of these events
as well as the condition of the birds at the end of the flock cycle.
Despite the importance of all of the above, transportation represents
one of the major factors affecting bird welfare and economical losses
primarily due to bird death.
Transportation of animals to slaughter is an essential component
of an intensive and geographically dispersed industry where large
numbers of birds must be transported from diverse locations to a
central slaughter facility. In transit, birds are exposed to a variety
of potential stressors including temperature, moisture, acceleration,
vibration, motion, impacts, fasting, withdrawal of water, social
disruption and noise. As a result, live haul and associated problems
are major determinants of the efficiency of broiler production by
affecting factors such as death on arrival (DOA), trim at slaughtering
and meat quality. Despite the importance of transportation at this
critical stage of the broiler production cycle, it has received
little research attention. Most work in this area has been completed
in the United Kingdom under the direction of Malcolm Mitchell and
Peter Kettlewell. Despite the quality of their work, it is impossible
to extrapolate their results to the harsh winter conditions of the
Canadian prairies. Research completed as a M.Sc. project by Tennille
Knezacek provides an indication of the temperature conditions during
transport in Saskatchewan and serves as the basis for this report.
The research helps us understand biological changes affecting birds
during transportation, and will hopefully allow for modifications
to reduce financial losses and improve the welfare of birds between
farms and the processing plant.
Experimental Details
A total of 31 trips were monitored with four used to help define
the principal research strategy and the remaining 27 to characterize
vehicle environmental conditions over a wide range of ambient temperature.
Data collection included an evaluation of the barn environment and
bird condition prior to loading, temperature and relative humidity
conditions on the transport vehicle during transport, death during
the trip, and bird condition upon arrival at the slaughtering plant.
The transportation system employed in Saskatchewan utilizes Anglia
Autoflow modules (Wortham Ling, Diss, Norfolk, England IP22 1SR)
that are loaded by forklift onto a trailer unit. The modules span
the width of the trailer and contain 12 or 15 crates, each holding
20 to 26 birds. The modules, which are stacked in pairs, were labeled
alphabetically and the crates within the modules were numbered.
Data loggers were placed in modules during loading and then the
transport vehicle was followed to Wynyard where the trailer unit
was driven into the live receiving area. Modules were immediately
removed from the trailer and each crate was inspected. Bird condition
was assessed and dead birds (DOA - dead on arrival) were removed
and identified for necropsy. After processing, the plant reports
were obtained for additional information, including the number of
birds that died during the lairage period (DOS - dead on shackling).
For cold weather transportation (winter, early spring and late
fall), both tarps on the trailer unit were lowered and vents running
midline through the roof of the trailer were adjusted according
to ambient conditions to provide air circulation. Under warmer conditions,
either one or both tarps were raised, and in summer, vents on the
front and rear of the trailer were occasionally opened.
Results
The four preliminary trips completed in winter demonstrated that
passive ventilation on tightly tarped transport trailers, while
allowing birds in the core of the trailer to maintain body temperature,
produced a heterogeneous distribution of temperate and humidity
conditions that were less than optimum. The results demonstrated
the potential for cold stress near air entry points and heat stress
in poorly ventilated areas. Because the data loggers were not placed
near the extreme outside of the trailer, it is probable that birds
were exposed to colder temperatures than outlined above. Therefore,
it was deemed essential to acquire a more complete picture of the
temperature variability in subsequent research.
In the principle study, the primary focus was to comprehensively
investigate horizontal and vertical temperature and humidity gradients
on the trailer through continuous monitoring with data loggers.
Journey length in the principle study varied from 140 to 240 minutes.
The range of ambient temperatures was -27.2°C to 21.9°C.
Ambient temperature affected the mean crate temperatures on the
transport vehicle. The linear relationship between ambient temperature
and mean temperature of the crates was stronger when the tarps were
raised (r2 = 0.91; y = 0.69x + 8.54) in comparison to when they
were lowered (r2 = 0.64; y = 0.35x + 11.29). This is a reflection
of the variable vent configuration and the impact of imperfect sealing
of the tarps at the lower temperatures, in contrast to the more
uniform and un-restrictive ventilation configurations at higher
temperatures. Some general temperature trends were obvious for most
trips. Within a row of crates, the middle crate was warmer than
those from the driver and passenger sides of the trailer. Under
cold conditions, temperatures at the floor of the trailer for all
stack locations were low. Similarly, temperatures were low at the
back of the trailer (roof, centre, floor). The tarps used for the
sides of the trailers are difficult to seal in these areas and as
a consequence cold air infiltrates the load. The highest temperatures
were found in the middle and upper front sections of the trailer.
This appears to be due to the distance from areas of air infiltration
and the natural forward movement of air on the load.
The open roof vent area affected temperature lift when the tarps
were down. As open vent area increased from 0.18 m2 to 2.0 m2, there
was a strong negative relationship between vent area and temperature
lift (crate temperature minus ambient temperature); but once the
vent area exceeded 2.0 m2, the degree of temperature lift remained
constant. This information indicates that air exchange can be controlled
somewhat by the area of vent opening, particularly when adjustments
are made to the front roof vents.
The degree of temperature lift was affected by tarp configuration
for trips with an ambient temperature above 6°C. Temperature
lifts of 3.3, 5.7 and 9.6°C were recorded when both tarps were
raised, one tarp was raised and both tarps were lowered, respectively.
With tarps raised, closed or open front and rear vent configuration
had little effect on the mean crate temperature and mean temperature
lift values.
Apparent Equivalent Temperature (AET) was used as an integrated
index that combined dry-bulb temperature and relative humidity to
give an indication of the effective bird temperature. This index
revealed that cold ambient temperatures resulted in potentially
dangerous conditions as a result of both cold and warm on-board
temperatures in combination with high relative humidity (Table 1).
Observations of wet birds, particularly in the middle of the modules
and core of the trailer, suggests that the moisture produced from
bird respiration, and the low ventilation rate are the primary factors
responsible for the high humidity conditions in the core of the
trailer. At intermediate temperatures, the majority of conditions
on the trailer are satisfactory. This was also true for warmer conditions
although the possibility of high temperature/relative humidity conditions
needs to be monitored particularly when the vehicle is stationary.
The level of death loss during 26 monitored trips was very low
with a mean of 0.13% and a range of 0.05 to 0.52%. These values,
associated with bird death occurring during the transportation period
only, are lower than the Canadian average for 2000 (0.40%) and the
average value found in a study from the UK (0.22%). However, the
DOA data from this research did not include death losses occurring
during the holding period prior to processing. Dead birds were categorized
according to the major factors judged to be associated with death.
These were transportation itself (34%), catching trauma (29.2%),
farm-related death (31.9%), death as a result of our data collection
(3.2%) and other reasons not readily associated (1.4%). It must
be emphasized that transportation may have contributed to death
occurring in all categories but that other factors made the birds
susceptible to dying. Ambient temperature affected the incidence
of birds dying during transport with the incidence of DOA broilers
being higher when the ambient temperature was < -16°C (0.27
vs 0.12%). Variability even within this temperature grouping suggested
that factors such as farm management and specific management of
the trailer units can affect this characteristic and that cold temperatures
do not automatically translate to elevated death loss. Examination
of incidence of dead on shackling on the monitored trips demonstrated
that bird lairage plays an important role in pre-slaughter bird
death (mean = 0.27%). Overall, the barns visited in this study were
well managed and contained birds in good condition. This may have
played a role in the low levels of death loss observed.
Conclusions
Winter transportation of broilers in Saskatchewan presents a considerable
challenge in terms of protecting birds from the cold and yet providing
adequate trailer ventilation. Although roof vents can be used to
control air exchange to some degree, passive air flow of this type
is variable because of the influence of vent location, truck speed,
prevailing winds, bird stocking density, etc. Similarly, air does
not enter the trailer in a planned fashion since there are no planned
inlets. Air enters primarily at the edges of the tarps (rear, bottom
and front) as they are difficult to seal, through unintentional
openings (poorly sealed front vents) or through roof vents. Ventilation
efficacy is further reduced by modules containing broilers that
block air flow and thereby influence the degree of ventilation that
occurs in various sections of the trailer. The above factors result
in heterogeneous temperature distribution from very cold near air
inlets to quite warm in poorly ventilated areas.
Overall, the industry is doing a reasonable job operating a broiler
transport system that allows little control besides the adjustment
of roof vents and trailer tarps, but does this research indicate
that we do not have a welfare concern during winter transport conditions?
Death losses during transport were low but trips were not monitored
under the most severe conditions that can occur in prairie winters.
In addition, low Apparent Equivalent Temperatures during winter
conditions are probably unacceptable. "Disasters" do occur
and the industry must strive to prevent their occurrence. Such losses
represent an economic loss to the entire broiler industry but more
importantly are not acceptable to Canadian consumers and should
not be acceptable to the broiler industry. Therefore we believe
that improvements to transport vehicles should be explored. We are
continuing research on this topic at the University of Saskatchewan
and our initial assessment is that passive ventilation will not
prove to be satisfactory. Therefore we are examining the potential
of using power ventilated transport vehicles which should provide
a uniform and suitable temperature and relative humidity environment
during transport.
The transport vehicle is central to pre-slaughter broiler management
and animal welfare, but farm management that produces healthy, dry
birds will minimize the negative effect of stress during this period
of time. Similarly the length of lairage and the quality of the
lairage environment affect animal welfare and economic loss prior
to slaughter.
Acknowledgements
Collaborators included G.P. Audren1, S. Stephens2
T. Crowe3, E.M. Barber3,4, Myles Bantle3,
A. A. Olkowski1, M.A. Mitchell5 and P.J. Kettlewell6.
1Department of Animal and Poultry Science,
University of Saskatchewan, Saskatoon, SK S7N 5A8; 2Department
of Veterinary Pathology, University of Saskatchewan,Saskatoon, SK
S7N 5B4; 3Department of Agricultural and Bioresource
Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9;
4Dean of Agriculture, University of Saskatchewan, Saskatoon,
SK S7N 5A8; 5Roslin Insitute, Roslin, Midlothian EH25
9PS, Scotland; 6Silsoe Research Institute, Wrest Park,
Silsoe, Bedfordshire MK45 4HS, UK.
The Chicken Farmers of Saskatchewan and Saskatchewan Agriculture
and Food Agricultural Development Fund for research funding.
Drs. B. Althouse, D.S. Derow and L. Belanger of the Canadian Food
Inspection Agency for DOA and DOS necropsy.
Lilydale Poultry for their cooperation and assistance.
Lilydale Poultry personnel: C. Gudmundson, M. Karakochuk and truck
drivers, including B. Bell, W. Bodnarchuk, A. Bucko, G. Gelech,
W. Jackson and R. Karakochuk.
Broiler catching crews.
Producers participating in the study: A. Buhler, Grand Slam/Shay
Don, H. Huizinga, JCJ Poultry, N. Keet, T. Kleinsasser, N. Langelaar,
D. Neufeld, M. Pickard, L. Regehr, P. Regehr, N. Sloboshan, W. Sloboshan,
A. Wohlgemuth, M. Wohlgemuth.
Technical assistance provided by Robert Gonda, Karen Schwean and
Dawn Abbott of the University of Saskatchewan.
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