APSS 2013 Proceedings - The University of Sydney

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Aust. Poult. Sci. Symp. 2013.....24 Once the heaps were formed, 10 iButton temperature data loggers (Maxim Integrated, San Jose, CA, USA) were inserted in each heap at five depths (0 cm, 5 cm, 10 cm 25 cm and 50 cm) so that each depth was replicated. Time of insertion and the location of each iButton were recorded. All iButtons were set to record temperature hourly. Six heaps, two from each moisture level, were covered with large polypropylene tarpaulin covering the entire heap to ground level. At day 7 of the experiment, all iButtons were collected and temperature data retrieved for analysis. A representative sample from each heap was also collected at the beginning (day 0) and end (day 7) of the experiment to determine moisture content. Experiment 2 was a simpler 2×2 factorial study with two levels of moisture, no added water (M0) and 10% added water (M10) and two levels of cover (with or without). iButtons were placed inside the heaps as in experiment 1 and temperature was recorded hourly for seven days. Litter samples were collected at the beginning and end of the experiment for the determination of moisture content. Data were analysed using analysis of variance to test the main effects (moisture, cover and depth) and their interactions. Significance of differences between levels within an effect were tested using student’s T test. Least squares means and ±standard errors of means (SEM), or simple temperature profiles without analysis are presented. III. RESULTS Experiment 1. There were significant effects of Depth (P < 0.0001) and Cover (P < 0.03) but not Moisture level (P = 0.21) on the mean temperature with a significant interaction between Moisture and Depth (P < 0.05). As expected, temperature was significantly lower on the heap surface (0 cm) than at any other depth. The mean temperature increased with increasing depth in low moisture content litter (M0), however, with moisture level M5 and M10, temperature increased with depth up to 10 cm and 5 cm respectively and then stayed relatively constant with a tendency to reduction at 50 cm depth (Figure 1 left). Application of covers increased overall mean temperature in the M0 litter only (Figure 1 right). Figure 1 - Mean temperature (±SEM) achieved in heaps at various depths (left) and with or without cover (right) at three moisture levels. Columns within moisture treatments not sharing a common letter are significantly different (P < 0.05). Exploration of the temperature profiles over time revealed that, overall, covering resulted in marginally higher temperatures from day one onward (Figure 3, left). Covering increased surface temperatures by approximately 10 °C between days 2 and 7 up to the end of trial. It also increased temperatures significantly at 5 and 10 cm depths, particularly later in the experiment (Figure 2). Addition of 10% moisture to the litter achieved about an extra 5 °C mean temperature from day 4 onward (data not shown). There was no significant difference between day 0 and day 7 moisture contents (P = 0.07) of litter, however there was a tendency towards increased moisture content following 7 days of heaping (Table 1). 180
Aust. Poult. Sci. Symp. 2013.....24 Figure 2 - Expt. 1. temperature profiles over time at various depths in heaps with (left) or without (right) covers. Experiment 2. There was a significant effect of Depth (P < 0.001), Moisture (P = 0.003) and Cover (P = 0.003) on the mean temperature of the heap with significant interaction between the effects of Depth and Cover (P < 0.008) and Moisture and Cover (P < 0.0004) but not Depth and Moisture (P = 0.61). In general, mean temperature increased with the depth in the heap. The mean temperature was higher at all depths in covered heaps apart from the surface (data not shown). The interaction between the effects of moisture and cover was because the effect of covering was only evident in the M0 litter (Figure 3, right). Thus addition of extra moisture or covering the heap increased mean temperature by approximately 10°C from day three onwards, but the effects are not additive. Raw moisture content data are presented in Table 1. Figure 3 - Temperature profile in heaps over time showing the overall effect of covering in experiment 1 (left) and the effects of cover and moisture level in experiment 2 (right). Moisture level Table 1 - Moisture contents of litter in Experiments 1 and 2 Cover Moisture level (%) Experiment 1 Experiment 2 Day 0 Day 7 % Change Day 0 Day 7 % Change M0 Yes 21.61 24.37 +12.7 13.01 10.23 -13.6 M0 No 23.10 27.07 +17.0 15.36 17.90 +14.6 M5 Yes 27.68 35.30 +27.5 M5 No 27.27 28.69 +5.2 M10 Yes 35.46 33.39 -5.8 25.78 28.24 +9.5 M10 No 33.33 37.13 +11.4 28.17 31.90 +13.2 181
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24 th ANNUAL AUSTRALIAN POULTRY SCI
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AUSTRALIAN POULTRY SCIENCE SYMPOSIU
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AUSTRALIAN POULTRY AWARD The Austra
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CONTENTS THE IMPORTANCE OF THE POUL
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SHORT COMMUNICATION SESSION # 1: (c
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SHORT COMMUNICATION SESSTION # 2: (
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HOT TOPIC 2: EMERGING DISEASES AND
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Aust. Poult. Sci. Symp. 2013.....24
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AUTHOR INDEX Name Page(s) Email Add
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Klein-Hessling, H 207 hkleinhesslin
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Van de Wouw, A 247 nnet.vandewouw@w
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