Microbiological analysis of composts produced on South Carolina poultry farms

Abstract

Aims: The purpose of this study was to determine whether the methods used in compost operations of small and medium‐sized poultry forms resulted in the production of an amendment free of foodborne pathogens. Methods and Results: Nine compost heaps on five South Carolina poultry farms were surveyed at different stages of the composting process. Compost samples were analysed for coliforms and enriched for Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes. The waste materials and composting practices differed among the surveyed farms. On two farms, new materials were added to heaps that had previously completed the active composting phase. Five compost heaps did not reach an internal temperature of 55°C, and c. 62% of all internal samples in the first composting phase contained moisture contents <40%. Escherichia coli was detected in 63% of the surface samples (n = 38) and 9·8% of the internal samples (n = 82) from the first composting phase, as compared with 16·7% of the surface samples (n = 12) and 0% internal samples (n = 24) from the second composting phase. Salmonella was detected in 26 and 6·1% of all surface and internal samples collected from heaps in the first composting phase, respectively, but was absent in all compost samples undergoing a second composting phase. The predominant Salmonella serotypes were Thompson, Montevideo and Anatum. Neither E. coli O157:H7 nor L. monocytogenes was detected in any of the samples. Conclusions: Our results indicate that the conditions at the compost surface are suitable for pathogen survival, and the complete composting process can result in the elimination of pathogens in poultry wastes. Significance and Impact of the Study: This research provides information regarding the effectiveness of the composting practices and microbiological quality of poultry compost produced by small‐ and medium‐sized farms. Ensuring the safety of compost that may be applied to soils should be an integral part of preharvest food safety programme.

Microbiological Safety of Chicken Litter or Chicken Litter-Based Organic Fertilizers: A Review

“…10 5 CFU/g in fecal samples collected from broiler chicken flocks [19]. L. monocytogenes is usually absent (negative) in chicken litter and poultry compost, and this pathogen therefore appears not to be a significant issue in chicken litter or chicken litter-based organic fertilizers [6,30]. There are also growing concerns about the presence of antibiotic-resistant pathogens in animal manures from both on-farm exposure and off-farm contamination.…”

“…This review thus focuses on the microbiological safety of chicken litter or chicken litter-based organic fertilizers. 26% surface and 6.1% internal samples (1st composting phase); absent in all samples (2nd composting phase) [30] E. coli is present in chicken litter with the prevalence rate as high as 100%; however, E. coli O157:H7 was not detected in chicken litter samples [28,29] or poultry compost samples [29,30]. The population of E. coli in reused chicken litter can reach up to 9.7 × 10 4 CFU/g while the population for single use litter has been found to be 4.2 × 10 5 CFU/g [6].…”

Validating Thermal Inactivation of Salmonella spp. in Fresh and Aged Chicken Litter

“…Prior to a challenge study, chicken litter was analyzed for background mesophiles and screened for Salmonella, as described previously (30). Ten grams of chicken litter was mixed with 90 ml of saline and plated onto TSA-R.…”

“…Chicken litter samples were adjusted to desirable moisture contents (30,40, and 50%) with sterile tap water using a spray nozzle (sterilized with 70% ethanol and rinsed with sterile tap water). A mixture of 3 Salmonella serovars was inoculated into the samples (1:100, vol wt Ϫ1 ) with a sterile spray nozzle at a final concentration of ca.…”

Veterinary Public Health Approach to Managing Pathogenic Verocytotoxigenic Escherichia coli in the Agri-Food Chain

“…Lung et al showed that E. coli O157:H7 inoculated at a level of log 10 7.00 CFU g −1 was nondetectable after 72 h in composted manure (83). Research by Shepherd et al showed that compost heaps covered with finished compost maintained temperatures under the physical covering that were around 7 to 15.5°C higher than in an uncovered heap, resulting in a faster reduction of E. coli O157:H7 than was observed in heaps covered with fresh straw or left uncovered (84). This validated recommendations of the U.S. Environmental Protection Agency for covering fresh compost (84).…”