Characterization of hatchery residues for on farm implementation of circular waste management practices

The conventional management of hatchery residues is associated with greenhouse gas and unpleasant odor emissions, the presence of pathogens and high disposal costs for producers. To address these issues, on-farm alternatives like composting, fermentation, and insect valorization are promising approaches. This study aims to characterize hatchery residues and define critical quality thresholds to identify effective processes for their management. Hatchery residue samples were collected bi-monthly over a year (N = 24) and were analyzed for proximate composition (dry matter, ash, energy, crude protein, crude lipid, crude fiber, carbohydrates), pH, color (L*a*b*, Chroma) and microbiological loads (total aerobic mesophilic counts, coliforms, lactic acid bacteria). Volatile fatty acid composition was also measured (N = 8). Significant correlation coefficients were found between TAM and LAB loads and residue characterization (pH, chroma, crude fibers, carbohydrates, and temperature). On a dry matter basis, residues were high in energy (2498 to 5911 cal/g), proteins (21.3 to 49.4 %) and lipids (14.6 to 29.1 %), but low in carbohydrates (0 to 15.3 %) despite temporal fluctuations. Ash content varied widely (8.6 to 49.1 %, dry matter) and is influenced by eggshell content. Microbiological loads were high for total aerobic mesophilic bacteria (6.5 to 9.1 log cfu/g), coliforms (5.4 to 8.5 log cfu/g) and lactic acid bacteria (6.7 to 9.0 log cfu/g). Valorization of hatchery residues on the farm will depends on the optimization of effective upstream stabilization processes. The critical points are discussed according to the valorization potentials that could be implemented on the farm from composting to upcycling by insects.

Utilization of polyethylene sleeves with forced aeration for composting of broiler carcasses on mass depopulation events: Laboratory-scale simulations and sensitivity analyses

Composting poultry carcasses and the infected litter is considered feasible during mass depopulation events in response to disease outbreaks. We demonstrate the effect of temperature (40, 50, 60 °C) and aerobic/anaerobic conditions on the degradation of broiler carcasses and broiler litter (BL) and the elimination of pre-inoculated Avian flu and Newcastle viruses and SalmonellaInfantis (3.3 × 10^5.6 EID₅₀, 7 × 10^6.0 EID₅₀ and 2 × 10⁷ CFU g-dry matter (DM)^-1, respectively). Six broiler carcasses and BL were inoculated and treated with a water-based foam, simulating a common culling method. After 30 days of composting, both viruses were eliminated under all conditions, whileSalmonellapersisted at 40 °C under aerobic and anaerobic conditions (7.4 × 10⁵and 4.4 × 10³CFU g-DM^-1, respectively). Mass losses were 42-44, 24-26, and 18-22% (aerobic) and 18-27, 21-23, and 0-7% (anaerobic) at 40, 50, and 60 °C, respectively. In the end, the associated odors were not typical of carcasses (aerobic), or they were strong and offensive (anaerobic). Considering the observed mass losses and biomass water holding capacity, we present a sensitivity analysis of the water balance expected in composting sleeves if they are utilized on mass depopulation events. Composting of the carcasses and the BL in enclosed sleeves with forced aeration, following culling by means of water-based foam will generate excess water, depending on sleeve volumes, aeration conditions, and co-addition of absorbing materials like sawdust. No excessive moisture is expected if dry culling methods are used.

Potential of Meta-Omics to Provide Modern Microbial Indicators for Monitoring Soil Quality and Securing Food Production

Soils are fundamental resources for agricultural production and play an essential role in food security. They represent the keystone of the food value chain because they harbor a large fraction of biodiversity—the backbone of the regulation of ecosystem services and “soil health” maintenance. In the face of the numerous causes of soil degradation such as unsustainable soil management practices, pollution, waste disposal, or the increasing number of extreme weather events, it has become clear that (i) preserving the soil biodiversity is key to food security, and (ii) biodiversity-based solutions for environmental monitoring have to be developed. Within the soil biodiversity reservoir, microbial diversity including Archaea, Bacteria, Fungi and protists is essential for ecosystem functioning and resilience. Microbial communities are also sensitive to various environmental drivers and to management practices; as a result, they are ideal candidates for monitoring soil quality assessment. The emergence of meta-omics approaches based on recent advances in high-throughput sequencing and bioinformatics has remarkably improved our ability to characterize microbial diversity and its potential functions. This revolution has substantially filled the knowledge gap about soil microbial diversity regulation and ecology, but also provided new and robust indicators of agricultural soil quality. We reviewed how meta-omics approaches replaced traditional methods and allowed developing modern microbial indicators of the soil biological quality. Each meta-omics approach is described in its general principles, methodologies, specificities, strengths and drawbacks, and illustrated with concrete applications for soil monitoring. The development of metabarcoding approaches in the last 20 years has led to a collection of microbial indicators that are now operational and available for the farming sector. Our review shows that despite the recent huge advances, some meta-omics approaches (e.g., metatranscriptomics or meta-proteomics) still need developments to be operational for environmental bio-monitoring. As regards prospects, we outline the importance of building up repositories of soil quality indicators. These are essential for objective and robust diagnosis, to help actors and stakeholders improve soil management, with a view to or to contribute to combining the food and environmental quality of next-generation farming systems in the context of the agroecological transition.

Impact of Soil Microbes and Oxygen Availability on Bacterial Community Structure of Decomposing Poultry Carcasses

The impact of soil with an intact microbial community and oxygen availability on moisture content, soil pH, and bacterial communities during decomposition of poultry carcasses was investigated. Poultry carcasses were decomposed in soil with or without a microbial community, under aerobic or anaerobic conditions. The samples collected in each microcosm burial set-up were analyzed by targeted 16S rRNA amplicon sequencing and Amplicon sequence variants (ASV) method. Our results showed that moisture was high in the burial set-ups under anaerobic conditions and pH was high in the burial set-ups under aerobic conditions. Meanwhile, the Chao1 and Shannon index significantly differed between the different burial set-ups and across different time points. In addition, bacterial taxa composition during the early period of decomposition differed from that of the late period. A total of 23 phyla, 901 genera, and 1992 species were identified. Firmicutes was the most dominant phyla in all burial set-ups throughout the decomposition. At day 60, Pseudogracilibacillus was dominant in the burial set-ups under aerobic conditions, while Lentibacillus dominated in the burial set-ups under anaerobic conditions. This study demonstrated that the soil microbial community and availability of oxygen significantly affected the changes in moisture content, pH, and bacterial composition during the decomposition process.

Simultaneous removal of ammonia and volatile organic compounds from composting of dead pigs and manure using pilot-scale biofilter

Odor emission is one of the most common problems associated with dead animals composting. Biofiltration treatment for eliminating exhaust odors formed during dead pigs and manure composting has been studied. The composting and biofiltration process consisted of two series of tests. Composting experimental trials lasted 6 weeks, and composting was performed using six pilot-scale reactor vessels. A total of 37 kinds of volatile organic compounds (VOCs) present in the air were identified, and temporal variations were determined during the 42 days of composting. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and trimethylamine (TMA) were identified as the main odors VOCs component according to odor active values (OAVs). Nine biofilter vessels containing mature compost were used in studying the effect of different (30, 60, and 100 s) empty bed retention times (EBRT) on the simultaneous removal efficiencies (REs) of NH₃, DMS, DMDS, DMTS, and TMA. Results indicated that the inlet concentration of NH₃ applied was 12-447 mg m^-3, and the average removal efficiencies were 85.4%, 88.7%, and 89.0% for EBRTs of 30, 60, and 100 s, respectively. The average REs of DMS, DMDS, DMTS, and TMA were 79.2%-95.4%, 81.9%-94.0%, 76.7%-99.1%, and 92.9%-100%, respectively, and their maximum elimination capacity (ECs) were 220, 1301, 296, and 603 mg m^-3 h^-1, respectively. The optimal EBRT for the stimulation removal of NH₃, DMS, DMDS, DMTS, and TMA was 60 s.Implications: Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and trimethylamine (TMA) were identified as the main odors VOCs component during dead pigs and manure composting. Biofilter with mature as media can be used to stimulation remove NH₃, DMS, DMDS, DMTS, and TMA, the optimal empty bed retention times EBRT was 60 s.

Management of swine mortalities through the use of a mixed composting-accelerating bio-inoculant

A composting-accelerating bio-inoculant (Bacillus subtilis, Talaromyces sayulitensis (HC1), Steinernema sp., and Heterorhabditis sp.) was evaluated in a composting process made up of a different mix of wood chips, pig manure, urine, and swine mortality (raw material RM). Three different treatments (T1, T2, and T3) were assessed, and physicochemical, microbiological, and entomological evaluations were carried out at 0 and 45 days of the composting process. The highest organic nitrogen (1.34 %) concentration was detected in swine mortality, whereas the highest total oxidizable organic carbon (39.1 %) concentration was observed in wood chips. Salmonella spp., was not identified in any of the raw materials. Clostridium spp., count was 5.5, 2.0, and 1.0 Log10 unit, for pig manure, wood chips, and swine mortality, respectively. Pig manure, swine mortality, and wood chip total coliform count was 6.21, 5.32, and 1 Log10 unit, respectively. Helminth eggs were not detected in any of the RM and Cryptosporidium spp., oocysts were occasionally found in pig manure and wood chips. Several types of flies were identified, Musca domestica, Muscina stabulans, Stomoxys calcitrans, Fannia canicularis, Sarcophaga sp., and Calliphora sp. Treatment 3 (45.11 % swine mortality, 33.33 % wood chips, and 21.55 %, urine and bio-inoculant) had the greatest total oxidizable organic carbon availability, the highest carbon/nitrogen (C/N) ratio (20.67, p < 0.05), and the lowest dipterous larvae count. Moreover, Salmonella sp., was not observed and had only low Clostridium spp., and fecal coliform count. The bio-inoculant's effect on C/N ratio, cation exchange capacity, and electrical conductivity were beneficial, and resulted in production of a fertilizer complying with EPA 600/1-87-014, EPA 40 CFR Part 258, and NTC5167/11 norms. According to the characterization protocols used in this study the compost was apparently free from bacterial and parasitic pathogens and minimal dipteran counts. Last, maturation time was 15 days shorter compared with control (C4).

Physical and chemical indicators of transformations of poultry carcass parts and broiler litter during short term thermophilic composting

Short-term on-site composting of poultry carcasses and broiler litter (BL) is considered as a feasible technology for pathogen elimination during events of mass mortality in poultry houses. However, factors related to mass losses and physical transformation of the poultry carcass, and associated emissions of volatile organic compounds (VOCs) and odors, have not been thoroughly evaluated. This study aims to characterize the degradation of separated carcass parts co-composted with BL and the associated air emissions during 30 days of enclosed composting at 50 °C with constant aeration. The study was carried out in lab-scale simulators using five mixtures containing feathers, rib bones, skins, breast muscles, and hearts and livers, prepared at a 1:2 volumetric ratio (carcass:BL). Dry mass losses reached 59.5, 41.1, 60.8 and 103.5% (based on weight) or 48.4, 29.6, 49.7, and 94.8% (based on CO₂-C and NH₃-N emissions), for rib bones, skins, breast muscles, and hearts and livers, respectively. Visually, most of the carcass parts were degraded, and the typical carcass odor had disappeared by the end of the 30 days. Out of 24 VOCs, dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) contributed 80.7-88.3% of the total VOC flux, considering the partial contribution of each part to the emissions involved with the whole carcass. DMDS, DMTS, benzaldehyde, methanethiol, pentanoic acid, and NH₃, contributed 90.5-97.9% of the odor activity values during composting. DMDS/DMTS ratio is suggested as a potential biomarker of stabilization and readiness of the compost for transportation toward further treatment or safe burial.

Risk assessments for quality-assured, source-segregated composts and anaerobic digestates for a circular bioeconomy in the UK

A circular economy relies on demonstrating the quality and environmental safety of wastes that are recovered and reused as products. Policy-level risk assessments, using generalised exposure scenarios, and informed by stakeholder communities have been used to appraise the acceptability of necessary changes to legislation, allowing wastes to be valued, reused and marketed. Through an extensive risk assessment exercise, summarised in this paper, we explore the burden of proof required to offer safety assurance to consumer and brand-sensitive food sectors in light of attempts to declassify, as wastes, quality-assured, source-segregated compost and anaerobic digestate products in the United Kingdom. We report the residual microbiological and chemical risks estimated for both products in land application scenarios and discuss these in the context of an emerging UK bioeconomy worth £52bn per annum. Using plausible worst case assumptions, as demanded by the quality food sector, risk estimates and hazard quotients were estimated to be low or negligible. For example, the human health risk of E. coli 0157 illness from exposure to microbial residuals in quality-assured composts, through a ready-to-eat vegetable consumption exposure route, was estimated at ~10^-8 per person per annum. For anaerobic digestion residues, 7 × 10^-3cases of E. coli 0157 were estimated per annum, a potential contribution of 0.0007% of total UK cases. Hazard quotients for potential chemical contaminants in both products were insufficient in magnitude to merit detailed quantitative risk assessments. Stakeholder engagement and expert review was also a substantive feature of this study. We conclude that quality-assured, source-segregated products applied to land, under UK quality protocols and waste processing standards, pose negligible risks to human, animal, environmental and crop receptors, providing that risk management controls set within the standards and protocols are adhered to.

Metagenomic analysis of soil and freshwater from zoo agricultural area with organic fertilization

Microbial communities drive biogeochemical cycles in agricultural areas by decomposing organic materials and converting essential nutrients. Organic amendments improve soil quality by increasing the load of essential nutrients and enhancing the productivity. Additionally, fresh water used for irrigation can affect soil quality of agricultural soils, mainly due to the presence of microbial contaminants and pathogens. In this study, we investigated how microbial communities in irrigation water might contribute to the microbial diversity and function of soil. Whole-metagenomic sequencing approaches were used to investigate the taxonomic and the functional profiles of microbial communities present in fresh water used for irrigation, and in soil from a vegetable crop, which received fertilization with organic compost made from animal carcasses. The taxonomic analysis revealed that the most abundant genera were Polynucleobacter (~8% relative abundance) and Bacillus (~10%) in fresh water and soil from the vegetable crop, respectively. Low abundance (0.38%) of cyanobacterial groups were identified. Based on functional gene prediction, denitrification appears to be an important process in the soil community analysed here. Conversely, genes for nitrogen fixation were abundant in freshwater, indicating that the N-fixation plays a crucial role in this particular ecosystem. Moreover, pathogenicity islands, antibiotic resistance and potential virulence related genes were identified in both samples, but no toxigenic genes were detected. This study provides a better understanding of the community structure of an area under strong agricultural activity with regular irrigation and fertilization with an organic compost made from animal carcasses. Additionally, the use of a metagenomic approach to investigate fresh water quality proved to be a relevant method to evaluate its use in an agricultural ecosystem.

Persistence of Non-O157 Shiga Toxin-Producing Escherichia coli in Dairy Compost during Storage

Dairy compost with 20, 30, or 40% moisture content (MC) was inoculated with a mixture of six non-O157 Shiga toxin-producing Escherichia coli (STEC) serovars at a final concentration of 5.1 log CFU/g and then stored at 22 and 4°C for 125 days. Six storage conditions-4°C and 20% MC, 4°C and 30% MC, 4°C and 40% MC, 22°C and 20% MC, 22°C and 30% MC, and 22°C and 40% MC-were investigated for the persistence of non-O157 STEC in the dairy compost. During the entire storage, fluctuations in indigenous mesophilic bacterial levels were observed within the first 28 days of storage. After inoculation, the non-O157 STEC population increased 0.69 and 0.79 log CFU/g in the dairy compost with 30 and 40% MC at 22°C within the first day, respectively; for all other storage conditions, the pathogen population decreased rapidly. After the 125-day storage, the reductions of non-O157 STEC for 4°C and 20% MC, 4°C and 30% MC, 4°C and 40% MC, 22°C and 20% MC, 22°C and 30% MC, and 22°C and 40% MC storage conditions were >4.52, >4.55, 3.89, >4.61, 3.60, and 3.17 log CFU/g, respectively. All the survival curves showed an extensive tail, indicating non-O157 STEC can survive at least for 125 days in the dairy compost. The survival data were analyzed with log-linear with tailing and Weibull models. Compared with the log-linear with tailing model, the Weibull model was found to be a better choice for predicting the survival of non-O157 STEC in dairy compost owing to a high overall R² value (0.8738 to 0.9909). The decay rate of non-O157 STEC was higher in dairy compost stored at 4°C compared with at 22°C, and the same trend was found for the compost with 40% MC versus 20% MC. In addition, two non-O157 STEC serotypes (STEC O145 and O45) were detected on the last day of the longitudinal study and may deserve special attention in the Big 6 STEC group. Our results have provided scientific data for risk assessment of the microbiological safety of dairy compost to control non-O157 STEC during subsequent storage of dairy compost.

A next generation sequencing approach with a suitable bioinformatics workflow to study fungal diversity in bioaerosols released from two different types of composting plants

Composting is used all over the world to transform different types of organic matter through the actions of complex microbial communities. Moving and handling composting material may lead to the emission of high concentrations of bioaerosols. High exposure levels are associated with adverse health effects among compost industry workers. Fungal spores are suspected to play a role in many respiratory illnesses. There is a paucity of information related to the detailed fungal diversity in compost as well as in the aerosols emitted through composting activities. The aim of this study was to analyze the fungal diversity of both organic matter and aerosols present in facilities that process domestic compost and facilities that process pig carcasses. This was accomplished using a next generation sequencing approach that targets the ITS1 genomic region. Multivariate analyses revealed differences in the fungal community present in samples coming from compost treating both raw materials. Furthermore, results show that the compost type affects the fungal diversity of aerosols emitted. Although 8 classes were evenly distributed in all samples, Eurotiomycetes were more dominant in carcass compost while Sordariomycetes were dominant in domestic compost. A large diversity profile was observed in bioaerosols from both compost types showing the presence of a number of pathogenic fungi newly identified in bioaerosols emitted from composting plants. Members of the family Herpotrichiellaceae and Gymnoascaceae which have been shown to cause human diseases were detected in compost and air samples. Moreover, some fungi were identified in higher proportion in air compared to compost. This is the first study to identify a high level of fungal diversity in bioaerosols present in composting plants suggesting a potential exposure risk for workers. This study suggests the need for creating guidelines that address human exposure to bioaerosols. The implementation of technical and organizational measure should be a top priority. However, skin and respiratory protection for compost workers could be used to reduce the exposure as a second resort.

Comparison of bacterial communities in leachate from decomposing bovine carcasses

OBJECTIVE

Burial is associated with environmental effects such as the contamination of ground or surface water with biological materials generated during the decomposition process. Therefore, bacterial communities in leachates originating from the decomposing bovine carcasses were investigated.

METHODS

To understand the process of bovine (Hanwoo) carcass decomposition, we simulated burial using a lab-scale reactor with a volume of 5.15 m3. Leachate samples from 3 carcasses were collected using a peristaltic pump once a month for a period of 5 months, and bacterial communities in samples were identified by pyrosequencing of the 16S rRNA gene.

RESULTS

We obtained a total of 110,442 reads from the triplicate samples of various sampling time points (total of 15 samples), and found that the phylum Firmicutes was dominant at most sampling times. Differences in the bacterial communities at the various time points were observed among the triplicate samples. The bacterial communities sampled at 4 months showed the most different compositions. The genera Pseudomonas and Psychrobacter in the phylum Proteobacteria were dominant in all of the samples obtained after 3 months. Bacillaceae, Clostridium, and Clostridiales were found to be predominant after 4 months in the leachate from one carcass, whereas Planococcaceae was found to be a dominant in samples obtained at the first and second months from the other two carcasses. The results showed that potentially pathogenic microbes such as Clostridium derived from bovine leachate could dominate the soil environment of a burial site.

CONCLUSION

Our results indicated that the composition of bacterial communities in leachates of a decomposing bovine shifted continuously during the experimental period, with significant changes detected after 4 months of burial.

Filth Fly Activity Associated With Composted and Noncomposted Beef Cadavers and Laboratory Studies on Volatile Organic Compounds

Commercial livestock facilities are faced with the challenge of managing large amounts of waste including manure and animal mortalities. One method of disposing of dead animals is composting. The cadavers are enveloped in carbon material that creates a barrier between the dead tissue and the surrounding environment. Dead tissue can release materials that not only contaminate the soil but also the groundwater and nearby surface water. Animal cadaver composting is designed to facilitate decomposition without the aid of carrion-feeding insects and reduce the presence of common pathogens associated with animal waste and dead tissue. The aim of this study was to evaluate insect activity associated with composted and exposed beef cadavers, specifically filth flies that can serve as mechanical vectors of important human pathogens such as E. coli 0157:H7. Greater numbers of all types of arthropods were trapped overall at the exposed animal site than the composted animal site. Most importantly, the number of filth flies was significantly lower at the composted site (P = 0.0009). Laboratory analysis of volatile organic compounds from composted and noncomposted rats indicated that known fly attractants such as dimethyl disulfide may be inhibited by the composting process. Implementing composting programs at livestock facilities could reduce the risk of flies spreading harmful pathogens to surrounding areas, including farms that grow fresh produce.

Investigation of the disposal of dead pigs by pig farmers in mainland China by simulation experiment

Dead pigs are a major waste by-product of pig farming. Thus, safe disposal of dead pigs is important to the protection of consumer health and the ecological environment by preventing marketing of slaughtered and processed dead pigs and improper dumping of dead pigs. In this study, a probability model was constructed for the disposal of dead pigs by pig farmers by selecting factors affecting disposal. To that end, we drew on the definition and meaning of behavior probability based on survey data collected from 654 pig farmers in Funing County, Jiangsu Province, China. Moreover, the role of influencing factors in pig farmers' behavioral choices regarding the disposal of dead pigs was simulated by simulation experiment. The results indicated that years of farming had a positive impact on pig farmers' choice of negative disposal of dead pigs. Moreover, there was not a simple linear relationship between scale of farming and pig farmers' behavioral choices related to the disposal of dead pigs. The probability for farmers to choose the safe disposal of dead pigs increased with the improvement of their knowledge of government policies and relevant laws and regulations. Pig farmers' behavioral choice about the disposal of dead pigs was also affected by government subsidy policies, regulation, and punishment. Government regulation and punishment were more effective than subsidy. The findings of our simulation experiment provide important decision-making support for the governance in preventing the marketing of dead pigs at the source.

Quantification of sodium pentobarbital residues from equine mortality compost piles

Sodium pentobarbital, a euthanasia drug, can persist in animal carcasses following euthanasia and can cause secondary toxicosis to animals that consume the remains. This experiment was conducted to observe the effects of composting on euthanized horse carcass degradation and sodium pentobarbital residues in compost material up to 367 d. Six separate compost bins were constructed on pastureland. Three bins served as the control while 3 served as the treatment. The carbonaceous material, or bulking agent, consisted of hardwood chips mixed with yard waste wetted to approximately 50% moisture content. Bulking agent was added to each bin at a depth of 0.46 m, creating the pad. A licensed veterinarian provided 6 horse carcasses for use in the experiment. These horses had required euthanasia for health reasons. All horses were weighed and then sedated with an intravenous injection of 8 mL of xylazine. After sedation the 3 horses in the treatment group were euthanized by intravenous injection of 60 mL of sodium pentobarbital. The 3 control group horses were anesthetized by intravenous injection of 15 mL of ketamine hydrochloride and then humanely euthanized by precise gunshot to the temporal lobe. Following euthanasia, each carcass was placed on the center of the pad and surrounded with 0.6 m of additional bulking agent. Serum and liver samples were obtained immediately following death. Compost samples were obtained on d 7, 14, 28, 56, 84, 129, 233, and 367 while soil samples were obtained on d -1 and 367. Each sample was analyzed for sodium pentobarbital concentration. Compost pile and ambient temperatures were also recorded. Composting successfully degraded soft tissue with only large bones remaining. Data illustrate that sodium pentobarbital was detectable up to 367 d in compost piles with no clear trend of concentration reduction. Drug residues were detected in soil samples indicating that sodium pentobarbital leached from the carcass and through the pad. These findings confirm the persistence of sodium pentobarbital from equine mortality compost piles and emphasize the importance of proper carcass management of animals euthanized with a barbiturate to reduce environmental impact and secondary toxicosis.

Biodegradation of prions in compost

Composting may serve as a practical and economical means of disposing of specified risk materials (SRM) or animal mortalities potentially infected with prion diseases (transmissible spongiform encephalopathies, TSE). Our study investigated the degradation of prions associated with scrapie (PrP(263K)), chronic waste disease (PrP(CWD)), and bovine spongiform encephalopathy (PrP(BSE)) in lab-scale composters and PrP(263K) in field-scale compost piles. Western blotting (WB) indicated that PrP(263K), PrP(CWD), and PrP(BSE) were reduced by at least 2 log10, 1-2 log10, and 1 log10 after 28 days of lab-scale composting, respectively. Further analysis using protein misfolding cyclic amplification (PMCA) confirmed a reduction of 2 log10 in PrP(263K) and 3 log10 in PrP(CWD). Enrichment for proteolytic microorganisms through the addition of feather keratin to compost enhanced degradation of PrP(263K) and PrP(CWD). For field-scale composting, stainless steel beads coated with PrP(263K) were exposed to compost conditions and removed periodically for bioassays in Syrian hamsters. After 230 days of composting, only one in five hamsters succumbed to TSE disease, suggesting at least a 4.8 log10 reduction in PrP(263K) infectivity. Our findings show that composting reduces PrP(TSE), resulting in one 50% infectious dose (ID50) remaining in every 5600 kg of final compost for land application. With these considerations, composting may be a viable method for SRM disposal.

Treatment alternatives of slaughterhouse wastes, and their effect on the inactivation of different pathogens: a review

Slaughterhouse wastes are a potential reservoir of bacterial, viral, prion and parasitic pathogens, capable of infecting both animals and humans. A quick, cost effective and safe disposal method is thus essential in order to reduce the risk of disease following animal slaughter. Different methods for the disposal of such wastes exist, including composting, anaerobic digestion (AD), alkaline hydrolysis (AH), rendering, incineration and burning. Composting is a disposal method that allows a recycling of the slaughterhouse waste nutrients back into the earth. The high fat and protein content of slaughterhouse wastes mean however, that such wastes are an excellent substrate for AD processes, resulting in both the disposal of wastes, a recycling of nutrients (soil amendment with sludge), and in methane production. Concerns exist as to whether AD and composting processes can inactivate pathogens. In contrast, AH is capable of the inactivation of almost all known microorganisms. This review was conducted in order to compare three different methods of slaughterhouse waste disposal, as regards to their ability to inactivate various microbial pathogens. The intention was to investigate whether AD could be used for waste disposal (either alone, or in combination with another process) such that both energy can be obtained and potentially hazardous materials be disposed of.

Field scale evaluation of bovine-specific DNA as an indicator of tissue degradation during cattle mortality composting

Currently, mortality compost is managed by temperature as extent of tissue degradation is difficult to assess. In the present study, field-scale mortality compost was constructed with composted brain tissue (Brain) and compost adjacent to brain tissue (CAB) sampled over 230 d. Following genomic DNA extraction, bovine-specific mitochondrial DNA (Mt-DNA) and bacterial 16S rDNA fragments were quantified using real-time PCR. Genomic DNA yield of Brain and CAB decreased rapidly (89-98%) and stabilized after 7 d. Compared to d 0, Brain Mt-DNA rapidly decreased (84-91% reduction on d 7). In CAB, Mt-DNA dramatically increased until d 28 (up to 34,500 times) thereafter decreasing by 77-93% on d 112. Quantification of bovine Mt-DNA indicates tissue degradation was initially characterized by rapid decomposition and release of cell contents into surrounding compost matrix followed by further degradation of Mt-DNA by flourishing microorganisms. Consequently, bovine Mt-DNA copies in compost matrix were reliable indicators of tissue degradation.