Full text of DOI:10.1093/japr/10.4.335

2001 Poultry Science Association, Inc.
E
FFECT OF
T
RANSPORT
ROILER IVE
EFECATION
C
AGE
HRINK
ATTERNS
H
EIGHT
ON
B
L
S
AND
D
P
N. L. TAYLOR, D. L. FLETCHER1, J. K. NORTHCUTT, and M. P. LACY
Department of Poultry Science, University of Georgia, Athens, GA 30602
Phone: (706) 542-2476
FAX: (706) 542-2475
e-mail: fletcher@arches.uga.edu
Primary Audience: Poultry Processors, Researchers
SUMMARY
A series of eight trials was conducted to determine the effect of transport cage height on broiler
defecation patterns during holding. Prior to treatment, broilers were held in pens with free access
to feed and water. In each trial, birds were randomly placed into nine experimental cages, allowing
a bird density of 447 cm2/bird. Cages were constructed of wire with perforated wooden tops set
at internal heights of 15.2 cm (short), 22.9 cm (normal), or 68.6 cm (tall). The “normal” height
was determined as an average for commercial broiler transport cages. Cages with broilers inside
were weighed, placed over preweighed manure catch pans, and held for 8 h at 26°C; the cages
and the pans were reweighed to determine live shrink and excreta weight. In the first two trials,
birds held in the short cages had a significantly greater live shrink than the broilers in the normal
or tall cages. However, observations that the cage designs might have adversely affected ventilation
led to a redesigning of the tops using wire fabric to improve ventilation. In the following six trials,
cage height had no significant effect on live shrink (4.2%) or excreta (1.8%). These results indicate
that transport cage height, relative to bird posture during transport, had no significant effects on
live shrink or defecation patterns of broilers.
Key words: Broiler live shrink, live bird holding, transport cage
2001 J. Appl. Poult. Res. 10:335–339
widely, with most companies scheduling broilers
D
ESCRIPTION OF
P
ROBLEM
for slaughter after 8 to 12 h of feed withdrawal;
however, these times are frequently shifted to
accommodate plant operations. In practice, feed
withdrawal begins in the grow-out house where
broilers have access to water but not feed for 2
to 5 h before catching and caging. The remaining
feed withdrawal time (3 to 10 h) is spent in
cages during transit or at the plant. Because of
the “zero tolerance” fecal requirement in the
USDA’s Pathogen Reduction, HACCP ruling,
which prohibits carcasses with visible fecal con-
Feed and water are routinely withdrawn from
market-aged broilers prior to slaughter to allow
sufficient time for voiding of the digestive tract
to minimize the potential for carcass fecal con-
tamination during evisceration. To be effective,
the feed withdrawal period should be long
enough for adequate intestinal emptying but
short enough to limit live weight loss, or broiler
“live shrink,” due to feed deprivation [1, 2, 3].
Commercial feed withdrawal schedules vary
1 To whom correspondence should be addressed.

336
JAPR: Research Report
tamination from entering immersion chillers,
poultry companies are re-examining feed with-
drawal programs on intestinal evacuation and
reduction of carcass contamination [4, 5].
ation could be limited during transportation be-
cause of the inability of birds to stand in the
transport coops. The objective of the present
study was to determine the effect of transport
cage height on broiler live shrink and defecation
patterns during holding. If the bird’s postures
during holding negatively affected defecation
then live shrink and the microbiological status
of the birds entering the processing plant could
also be affected.
Previous research has shown that environ-
mental conditions as well as length of feed with-
drawal can affect live shrink. Hale [6] described
a seasonal effect on live shrink. It was noted
that high environmental temperatures combined
with long holding times caused excessive live
shrink [6]. Shackleford et al. [7], Kettlewell [8],
and Hoxey et al. [9] also reported increased
weight losses due to high environmental temper-
atures. These environmental extremes, along
with other factors such as broiler health, feeding
programs, excitement during the withdrawal pe-
riod, light or dark conditions during feed with-
drawal, and length of time broilers are held in
cages before processing have been reported to
affect the rate of digestive tract clearance [5, 10,
11, 12, 13]. Because of these factors, the rate of
live shrink for market-aged broilers held without
feed for 8 to 24 h has been reported to vary
between 0.18 and 0.6% of the bird’s body weight
per h of feed withdrawal [1, 5, 13, 14].
Summers and Leeson [15] reported that
broilers held in cages during feed withdrawal
retained intestinal contents longer than broilers
left on litter with access to water. Farr [16] indi-
cated that the physiological stress on broilers
caused by catching and caging resulted in an
immediate halt in absorption of intestinal con-
tents by the broilers for several hours. Savage
[17] suggested that feed clears a broiler’s crop
and proventriculus within the first 4 to 5 h of
feed withdrawal, provided water is available.
These findings conflict with those of May and
Deaton [10] who compared intestinal contents
of broilers after feed withdrawal when birds
were held in cages, held on litter without water,
or held on litter with water available ad libitum.
It was reported that broilers held in cages had
more material in the crop after 2 and 4 h and
more material in the proventriculus and gizzard
after 6 h than broilers held on litter, irrespective
of water withdrawal [10].
M
ATERIALS AND
M
ETHODS
One hundred twenty, 5-wk-old male broilers
were obtained from each of two separate com-
mercial sources and were transported to the Uni-
versity of Georgia Research Facility. They were
held in litter-floored pens in an environmentally
controlled house using standard broiler manage-
ment procedures and with free access to feed
and water until they reached 6 wk of age. Each
broiler flock was used for four trials. During the
study, birds were completely randomized among
treatments and replicate trials. A minimum of 3
d between each experimental trial was used to
allow birds to partially recover from the stresses
associated with handling.
CAGES
Nine experimental transport cages were con-
structed using an open wire fabric (square mesh
approximately 2.5 cm × 2.5 cm). Each cage was
61 cm wide by 66 cm deep, allowing for a nine-
bird placement density of 447 cm2/bird. Cages
were constructed with false bottoms of the same
wire fabric and were fitted approximately 5 cm
over excreta catch pans. Three replicate cages
were used with the tops set to allow for internal
heights of 15.2 cm (short), 22.9 cm (normal),
and 68.6 cm (tall) for each treatment. The normal
height was estimated as an average height for
commercial broiler transport cages. The short
height was determined by observation to not
allow the bird to assume an upright or standing
posture but would allow limited movement. The
tall cages were set such that there was no limita-
tion to the birds’ standing or vertical postures.
In Trials 1 and 2, the cage tops were constructed
using perforated wood, and in Trials 3 through
8, the tops were constructed using the same wire
fabric as used for the cages to allow for better
ventilation.
Savage [17] indicated that birds often evacu-
ate while drinking water due to their posture
(standing with neck stretched upward). It has
also been noted by field personnel that excreta
often accumulates near the waterers [18]. Evacu-

TAYLOR ET AL.: TRANSPORT CAGE HEIGHT
EXPERIMENTAL TRIALS
337
can’s multiple-range option of the SAS/STAT
software [21].
For the trials, nine birds were randomly
placed into each of the nine cages. The cages
with the birds were weighed and placed over
preweighed excreta collection pans. Caged broil-
ers were held in the same temperature controlled,
enclosed rooms in which they were reared at
26°C for 8 h. At the end of the holding period,
the loaded cages and the excreta collection pans
were weighed. After weighing, the tops of the
cages were opened, allowing birds unlimited
ability to stand and move about freely in the
open cages, the cages were replaced over the
manure collection pans for an additional 10 min,
and the excreta pans were reweighed. This pro-
cedure was followed to determine if the posture
during holding caused decreased evacuation, co-
lon loading, and would result in compensatory
defecation. Each excreta catch pan was exam-
ined, and cecal plugs were enumerated.
R
ESULTS AND
D
ISCUSSION
Table 1 shows the results for bird weight,
live shrink, excreta, and excreta as a percentage
of total live shrink for Trials 1 through 8. As
expected, bird weights increased significantly
for the four trials within each flock as the birds
aged. There were no significant flock or trial
effects for percentage live shrink, percentage
excreta, or excreta as a percentage of total live
shrink. The results for treatments are shown in
Table 2. For Trials 1 and 2, the randomization
of birds appeared successful, as there were no
significant differences in bird weight by treat-
ment group and no treatment by replicate inter-
actions.
A significant difference in live shrink was
observed in Trials 1 and 2 (Table 2). Birds in
the short cages exhibited significantly more live
shrink (5.3%) compared to the birds in the nor-
mal height cages (4.3%) and the tall height cages
(4.5%). Although this significant difference in
live shrink was observed, no significant differ-
ences in the collectable excreta, excreta as a
percentage of live shrink, or presence of cecal
plugs in the excreta were observed for Trials 1
and 2. It was noted that during these initial trials,
the birds in the short cages, constrained by a
perforated wooden board top, were panting more
than those in the other treatments. It was con-
cluded that the increased weight loss of this
STATISTICAL ANALYSIS
The weight data were used to determine av-
erage bird weight, live shrink, collectable ex-
creta, collectable excreta weight as a percentage
of live shrink, and number of cecal plugs per
cage [19]. The experimental design consisted of
eight trials, three treatments (cage heights), three
replicate cages per treatment and trial, and nine
birds per cage (total cage observations = 72)
[20]. Data were analyzed using analysis of vari-
ance option of the general linear model (GLM)
procedure, and means were separated using Dun-
TABLE 1. Mean ( standard error of the mean) for average bird weight (cage weight/number of birds per cage),
percentage live shrink, percentage excreta, and excreta as a percentage of total shrink per cage for Trials 1 to 8
BIRD WEIGHT
(kg)
LIVE SHRINKA
(%)
EXCRETAB
(%)
EXCRETA %
OF SHRINKC
FLOCK
1
TRIAL
1
2
3
4
5
6
7
8
1.89g
2.50d
2.73b
3.03a
1.64h
2.00f
2.37e
2.59c
0.02
0.03
0.02
0.03
0.02
0.02
0.01
0.03
4.6
4.8
4.2
4.3
4.2
3.9
4.3
4.6
0.1
0.3
0.2
0.6
0.1
0.1
0.1
0.2
2.2
2.1
1.7
1.5
1.6
1.9
1.9
1.9
0.1
0.2
0.1
0.1
0.1
0.1
0.1
0.1
48.2
42.5
40.5
49.6
39.2
48.6
44.0
41.7
0.7
1.3
0.5
13.5
1.0
0.8
1.1
0.6
2
a–hMeans within a column followed by different superscript letters differ significantly (P < 0.05).
ALive shrink (%) = ((initial live bird cage weight − 8 h live bird cage weight)/initial live bird cage weight) × 100.
BExcreta (%) = (collected cage excreta weight/initial live bird cage weight) × 100.
CExcreta % of shrink = (cage excreta weight (g)/cage shrink weight (g)) × 100.

338
JAPR: Research Report
TABLE 2. The effect of transport cage height (short, normal, tall) on the mean ( standard error of the mean)
average bird weight (cage weight/number of birds per cage), live shrink, excreta, excreta percent of total shrink,
and presence of cecal plugs in Trials 1–2, and Trials 3–8
BIRD WEIGHT
(kg)
LIVE SHRINKA
(%)
EXCRETAB
(%)
EXCRETA %
OF SHRINKC
CECAL
TRIALS
1–2
TREATMENT
PLUGSD
Short
Normal
Tall
2.21
2.16
2.22
0.14
0.13
0.16
5.3a
4.3b
4.5b
0.3
0.1
0.1
2.4
1.9
2.1
0.2
0.1
0.1
44.6
44.7
46.8
2.0
1.7
1.6
0.3
3.3
3.0
0.3
1.5
1.0
P
0.940
0.012
0.132
0.618
0.161
3–8
Short
Normal
Tall
2.39
2.38
2.41
0.11
0.12
0.11
4.4
4.2
4.1
0.2
0.1
0.2
1.8
1.7
1.8
0.1
0.1
0.1
43.1
41.1
47.6
2.7
1.4
6.0
2.6
3.2
3.1
0.5
0.6
0.4
P
0.490
0.545
0.292
0.429
0.118
a,bMeans within a column followed by different superscript letters differ significantly (P < 0.05).
ALive shrink (%) = ((initial live bird cage weight − 8 h live bird cage weight)/initial live bird cage weight) × 100.
BExcreta (%) = (collected cage excreta weight/initial live bird cage weight) × 100.
CExcreta % of shrink = (cage excreta weight (g)/cage shrink weight (g)) × 100.
DCecal plugs = number of cecal plugs per cage.
treatment might have been due to evaporative
cooling due to inadequate ventilation. Holding
temperature has previously been shown to affect
live shrink [6, 7, 8, 9]. For this reason, the cage
tops were redesigned for Trials 3 through 8, with
the same wire mesh used for the cages, to allow
better ventilation.
After the tops were redesigned, no signifi-
cant cage height effects on any of the parameters
tested were observed in Trials 3 through 8 (Table
1). Birds averaged a body weight of 2.39 kg, a
live shrink of 4.2%, and 3 cecal plugs per cage.
The live shrink values we observed are consis-
tent with published live shrink values for this
period [22]. These data indicate that the posture
capability of birds during transport and holding
does not affect 8-h defecation or live shrink
profiles. Because birds of different ages and
weights are often transported in the same con-
tainers, the interactions between bird weight and
cage height should not influence live shrink or
defecation.
CONCLUSIONS AND
APPLICATIONS
1. Broiler transport cage height had no effect on defecation patterns, live shrink, or cecal shedding.
2. Cage ventilation, as a function of transport cage design (height, solid floors, dimensions, etc.),
may have more of an effect on broiler live shrink than cage height on bird behavior.
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ACKNOWLEDGMENT
This research was supported in part by stat and Hatch funds
allocated to the Georgia Agricultural Experiment Station. The authors
express appreciation to Reg Smith, Meihua Qiao, David McNeal,
and Erica Fletcher for their technical assistance.
18. Savage, S.I., 2936 Summer Rd., Moultrie, GA 31768. Per-
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