Efficacy of Broiler Litter Composting Studied05 July 2013
US - Researchers have studied the temperatures reached in windrows of broiler litter composted between flocks to control pathogens. This work is a first step to gauge the efficacy of composting, which is a standard procedure in US broiler production.
The efficacy (proportion of windrow cross-section) of windrow composting has been studied as a treatment method for reducing microbial populations as measured by time-temperature goals in used broiler litter by researchers based in Mississippi.
According to first-named author, A.M. Schmidt of the University of Nebraska in a paper published in Journal of Applied Poultry Science, in-house windrow composting of broiler litter has been suggested as a means to reduce microbial populations between flocks. Published time-temperature goals are used to determine the success of the composting process for microbial reductions.
Spatial and temporal density of temperature measurement can influence the accuracy in determining what portion of a windrow section has achieved specified time-temperature goals, the researchers explain.
In their study, windrow section temperature was recorded every two minutes for seven days on a 10 × 10-cm grid in 183cm (width) × 91cm (height) windrow sections. In five windrow sections, ordinary kriging was used to predict the mean portion of the windrow cross-sectional area reaching time-temperature goals of 40°C for 120 hours, 50°C for 24 hours and 55°C for four hours.
Based on these results, 88.5 ± 2.0%, 80.8 ± 3.9% and 38.4 ± 11.7% of the windrow cross-sectional area can be expected to reach published microbial reduction time-temperature goals of 40°C for 120 hours, 50°C for 24 hours and 55°C for four hours, respectively.
Schmidt co-authors say their study illustrates the need to monitor temperature at multiple locations within windrowed litter to characterise heating profiles.
They recommend that temporal and spatial sampling densities are standardised so that temperature profiles in windrowed broiler litter can be properly characterised.
Additional research should be conducted to determine the degree of pathogen destruction achieved in the various time-temperature regions of the windrow pile, the researchers added.
Schmidt A.M., J.D. Davis, J.L. Purswell, Z. Fan and A.S. Kiess. 2013. Spatial variability of heating profiles in windrowed poultry litter. J. Appl. Poult. Res. 22(2):319-328. doi: 10.3382/japr.2012-00700
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