Suitability of sunflower-hulls-based turkey litter for on-farm turkey carcass composting

Abstract

Environmentally safe disposal of turkey carcasses is vital to a farm's bio security and prevention of disease outbreak. Carcass disposal by on-farm composting is considered a viable mortality management option. In this study, sunflower-hulls-based (SHB) turkey litter was used to examine the suitability of on-farm carcass composting under North Dakota climatic conditions. This study was conducted at a turkey farm in North Dakota, USA. The farm raised four flocks of 35,000 to 40,000 turkeys per flock per year and each flock was approximately six to seven weeks apart in age. The mortality rate for this farm was very low i.e., <1%. The static piles were prepared using a front-end loader. A base layer of 0.30 m was prepared with turkey litter removed from the barns between flocks. One layer of turkey mortalities were placed on top of the base layer and were covered with another 0.30 m layer of litter. In all trials, dead turkey/litter ratio (weight basis) was 1:3. Hobo data loggers were placed at predetermined depths and locations to monitor temperature changes continuously throughout the composting process. Litter samples were collected before, during, and after final composting for determining carbon (C), nitrogen (N), phosphorus (P), pH, fibers, electrical conductivity, and moisture content. Compost maturity tests were performed during and following completion of active composting process. Overall, SHB turkey litter was able to sustain temperatures of 55°C for 3-10 days during composting even though pile moisture content and carbon: nitrogen (C:N) ratio were lower than the recommended range of 40-65% and 25-30:1, respectively. A sustained temperature of 55°C is considered enough to destroy most pathogens. However, the normal practice of composting for 40-65 days was not enough to obtain matured compost due to high percentages of fibers such as cellulose, hemicelluloses, and lignin content in sunflower hulls. Therefore, the compost mix obtained from a finished pile may be reused for the next pile for complete degradation. Turning of the compost pile can be delayed and water can be added periodically to compensate pile moisture losses, eventually improving degradation of sunflower hulls and carcasses in turkey mortality compost piles.