An Improved Design for Biocontained Composting of Cattle Mortalities.
Xu, W., Xu, Y., Reuter, T.R., Gilroyed, B.H., Jin, L., Stanford, K.I.M., Larney, F.J., and McAllister, T.A. (2010). "An Improved Design for Biocontained Composting of Cattle Mortalities.", Compost Science & Utilization, 18(1), pp. 32-41.
Lack of uniform heating and peak temperatures lower than 55°C reduce the utility of beef cattle mortality composting. In a previous study, beef cattle mortalities were placed on a 40-cm straw base and covered with 160-cm manure, and compost reached 50°C with 20% reduction in bovine mitochondrial DNA (a 171- bp fragment; Mt171) at 160-cm depth after 147 d of static composting. Two modifications from the previous study’s methodology were made: (1) carcasses were raised to 100-cm depth by placing them on an additional 60-cm layer of manure and (2) feedlot manure with 60% moisture content at construction was used. Temperature profiles at depths of 40, 100, and 160 cm all reached 55°C after 7 d, and remained above 55°C for at least 70 d. The bovine Mt171 fragment was degraded 75% by d 112 and 86% by d 230 at 100-cm depth. Carcass soft tissues were almost completely decomposed, with a 99% reduction in genomic DNA and a 92% decrease in Mt171 fragment after 230 d. Levels of coliform bacteria were below 10 CFU g-1 dry wt at all depths on d 230. The modified cattle mortality composting system was characterized by higher peak temperature, longer uniform heating, and faster bovine tissue degradation compared to the previous study. This biocontained composting system could offer effective containment and control of a disease outbreak in which the infectious agent is sensitive to temperatures between 55-62°C.
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