887
Effects of different cooling interventions on stationary livestock trailers at a commercial packing plant
The objective was to determine effects of different cooling interventions on trailer temperature (T), relative humidity (RH), and transport losses over 20 minutes prior to unloading. Three treatments included: 1. Control (no water or fans), 2. Fan (20 min in front of a bank of fans), and 3. Shower+Fan (5 minutes of showering using the internal trailer system followed by 20 min in front of a bank of fans). Data was collected using HOBO data loggers placed inside the trailer upon arrival at the packing plant on 150 trailers in blocks where all 3 treatments were represented with 60 min of each other. Data was summarized at time points 0, 5, 10, 15, and 20 min and was analyzed with proc mixed in SAS using block as a random effect. Results on trailer T (Table 1) indicate that the Control treatment increased numerically over time, the Fan treatment prevented a rise in T, and the Fan+Shower treatment was the coolest (P<0.05) at all time points. RH inside the trailers was similar (P>0.05) in the Control and Fan treatment, but higher (P<0.05) in the Shower+Fan treatment at all time points (Table 2). No differences were determined on the incidence of dead on arrivals (P=0.87) or fatigued animals (P=.077). Further investigation of the data revealed an interaction (P=0.02) between treatment and environmental temperature where the temperature differences between treatments become greater at higher environmental temperatures.
Table 1. LSMeans of the Difference Between Trailer and Environmental1 Temperatures (⁰C) During the 20 Min Prior to Unloading by Treatment |
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Time Interval |
Control |
|
Fan |
|
Fan+Shower |
|
SEM |
P-value |
0 |
0.30 |
a |
0.82 |
a |
-0.78 |
b |
0.28 |
<.0001 |
5 |
1.04 |
a |
0.65 |
a |
-0.86 |
b |
0.23 |
<.0001 |
10 |
1.52 |
a |
0.43 |
b |
-0.61 |
c |
0.20 |
<.0001 |
15 |
1.77 |
a |
0.38 |
b |
-0.43 |
c |
0.20 |
<.0001 |
20 |
2.11 |
a |
0.52 |
b |
-0.25 |
c |
0.21 |
<.0001 |
1Average environmental placment temperature was 27.53⁰C |
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abcmeans within a row lacking common superscripts are different (P<0.05) |
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Table 2. LSMeans of Relative Humidity (%) by Treatment |
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Time Interval |
Control |
|
Fan |
|
Fan+Shower |
|
SEM |
P-value |
0 |
56.51 |
a |
56.27 |
a |
69.52 |
b |
2.43 |
<.0001 |
5 |
59.15 |
a |
56.46 |
a |
64.76 |
b |
2.58 |
<.0001 |
10 |
57.93 |
a |
57.32 |
a |
63.23 |
b |
2.59 |
0.0006 |
15 |
57.63 |
a |
57.50 |
a |
62.07 |
b |
2.65 |
0.0044 |
20 |
57.58 |
a |
57.43 |
a |
60.60 |
b |
2.67 |
0.0319 |
abcmeans within a row lacking common superscripts are different (P<0.05) |
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Keywords: Swine, Trailer, Cooling, Fans