APSS 2013 Proceedings - The University of Sydney

Aust. Poult. Sci. Symp. 2013.....24
LITTER PASTEURIZATION: EFFECTS OF COVER AND MOISTURE LEVEL ON THE
TEMPERATURE OF THE LITTER HEAP
A.F.M.F. ISLAM 1 , S.W. WALKDEN-BROWN 1 and B. WELLS 2
Summary
Two on-farm trials were conducted to examine the effects of adding extra moisture and
covering on temperature profiles of broiler litter heaped in-shed for pasteurisation before
reuse. Covering of litter heaps with tarpaulins increased heap temperatures by 5–10 °C
particularly near the surface of the heap and also helped maintain high temperatures longer.
Adding up to 10% water (w:w) also increased heap temperatures where litter moisture
content was below 25%. However the two effects were not additive with no beneficial effect
of covering observed at high moisture levels. This information may be useful for optimising
litter pasteurization protocols to achieve early and uniform high temperatures.
I. INTRODUCTION
Limited availability and high cost of chicken bedding materials are driving some broiler
producers to reuse litter for multiple chicken batches. Partial pasteurization of litter between
batches by heaping or windrowing for up to ten days can greatly assist in reducing pathogen
carryover in litter to the next batch of chickens. We have previously reported litter
temperatures of 50–70 °C inside broiler litter heaps between days 3 and 10 after heaping,
depending on depth within the heap (Walkden-Brown et al., 2010). The surface of the heaps
remained relatively cool (20–40 °C) and turning at day 3 significantly increased temperatures
after turning. This process was shown to eliminate or greatly reduce the infective load of
viral pathogens and coccidia in the litter (Islam et al., 2010). However, current industry
demand is for short batch turnaround times of six days or less with a strong preference to
avoid turning litter during pasteurisation if possible. Thus there is demand for a “quick
uniform pasteurisation” of litter without turning. There are reports in the USA that both
increased moisture level (Schmidt et al., 2010) and covering (Macklin et al., 2006) of litter
can elevate heap temperature significantly.
The objective of the current study was to investigate the use of these methods alone and
in combination to accelerate the increase in temperature following heaping, increase the
maximum temperature achieved and to achieve greater uniformity of temperature in the heap,
relative to untreated heaps particularly near the surface.
II. MATERIALS AND METHODS
Experiment 1 utilized a 3 (moisture) × 2 (cover) factorial design with two replicates.
Polypropylene tarpaulin covers were or were not applied to litter heaps with three levels of
added water (w:w) viz. none (M0), 5% (M5) or 10% (M10). The experiment was conducted
on a Sydney farm with one tunnel ventilated and two conventional open-sided sheds. The
original litter was pine shavings and were preparing for the 3 rd batch of chickens having an
average moisture level of 21-23%. Twelve litter heaps were prepared in total, three in the
smallest shed, four in the medium shed and five in the largest tunnel ventilated shed. The
floor area of each shed was divided into the requisite number of sections and weight of the
litter in each section was estimated. The required amount of water for each heap was added
during the preparation of heaps by a hose for which the flow rate had been measured.
1 School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351.
2 Wells Avian Consultancy, Glenorie, NSW, 2157.
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