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NO. 13 OCT 2018Contributors:Lori Miller, United States Departmentof Agriculture (USDA);Gary Flory, Virginia Department ofEnvironmental QualityCarcass management forsmall- and medium-scalelivestock farmsPractical 2Approachesto Carcass erencesn the event of an animal disease outbreak,such as highly pathogenic avian influenza,foot and mouth disease, African Swine Fever,or Lumpy Skin Disease, many animals will dieof the disease or may be sacrificed to preventpathogen spread. The carcasses will then require immediate safe management. Carcassmanagement options include onsite composting, burial or burning, as well as offsitelandfill, incineration or rendering, if thosetechnologies are readily available.Based on local experiences during recentanimal disease outbreak responses, carcassmanagement can be very challenging. Theremay be significant biosecurity and environmental risks from carcass management techniques, depending on how they are implemented. For example, storage of carcassesprior to disposal can risk spread of pathogensthrough several routes, such as attractingflies; liquids may leach to ground and surfacewater during storage and burial; burning may1produce hazardous air emissions; and improperly constructed compost piles may notinactivate pathogens.Effective carcass management achievestwo primary goals: 1) to contain pathogens toprevent further spread of disease to animalsand humans; and 2) to protect drinking water,air and soil. Both of these goals relate to human, animal and ecosystem health, which arepart of the One Health concept.One Health is a mechanism to addressthreats and reduce risks of infectious diseases at the animal-human-ecosystem interface.Key aspects of One Health include surveillance and disease intelligence at the threehealth domains, effective biosecurity duringinfectious disease outbreaks, and other important aspects. Effective carcass management directly supports these aspects and willbe discussed in more detail throughout thisarticle.Carcass management can be performedonsite or offsite by a variety of methods; theselected method depends on the specificsite conditions, including locally available resources and type and size of operation. z
NO. 13 OCT 2018The focus of this article is on small- to medium-sized operations (up to 5,000 poultry, 128pigs or 25 cattle, totaling about 11 metric tonsof material). However, it should be noted thatdifferent considerations, beyond the scopeof the current document, must be taken intoaccount for large commercial production operations greater than 5,000 poultry, 128 pigsor 25 cattle. The response is assumed to bestamping out, where all susceptible animalson the farm are destroyed and their remainsare disposed of, or a situation where animalsdied from the pathogen. This article does notaddress consumption of protein by humans. Itis further assumed that access to engineeredlandfills, controlled incineration and rendering is limited. Therefore, this article will focussolely on burial (traditional deep burial andinnovative above-ground burial), open-burning in pyres, and composting. zApproaches to CarcassManagementSelecting Site-specific DisposalOptionsIdeally, every farm should have a plan for howthey would manage carcasses in case of anoutbreak. The plan should provide details ofhow to implement all the disposal optionsthat apply to the specific site and situation tofacilitate flexibility for carcass management.The responders may choose to use one ormore of the different disposal methods, depending on the circumstances. Detailed information about advantages, disadvantages,applicability, cost factors and other considerations for each disposal option are presented in subsequent sections of this article.A section comparing the options follows thedetailed discussion of each disposal option. zDescription of Disposal OptionsThe following subsections provide detaileddescriptions of burial (deep burial and aboveground burial); burning (pyres, air curtainincinerators, and mobile crematoria); andcomposting.BurialBurial, for the purposes of this article, includes traditional deep burial, as well asa new and innovative above-ground burialprocess.Figure 1DEEP BURIAL SCHEMATICLeachate Levels:N 12,600 mg/L0 m BGSWHO Drinking WaterStandard:N 50 mg/LMinimum 33 mBURIAL PIT4 m BGSSOILWELLLEACHATE10 m BGSGROUNDWATER FLOW DIRECTION12 m BGSSOILBGS - below ground surface; m - meter(s); mg/L - milligrams per liter; N - Nitrogen; WHO - World Health OrganizaƟonBARNBURIAL PITLEACHATE/ GROUNDWATERඹHOMEWELLSource: Lori Miller, USDA, 2018Deep burialDeep burial involves removing soil from theground to a depth of three to four meters,piling the soil nearby for later use, depositing the carcasses into the excavated area, andthen covering the carcasses with the soil thathad been previously removed. Once buried,carcasses undergo anaerobic decompositionand break down into minerals and organicmaterial. This is a slow process and may takedecades. The anaerobic decomposition process generates body fluids (leachate) whichwill slowly penetrate into the native soil beneath the burial site and may reach groundwater (see Figure 1).Depending on the soil type and watertable depth, there may be risks to humanhealth and the environment associated withcontaminating groundwater. For example,carcass leachate is shown to contain over12,000 milligrams/liter (mg/L) nitrogenas ammonium, whereas a maximum of 10mg/L of nitrates in drinking water is deemedsafe by some countries. Excess nitrates cancause methemoglobinemia, which is potentially fatal to infants, as well as eutrophication, which kills fish. A variety of physical,chemical or biological processes may, under favourable conditions, reduce the mass,toxicity, mobility, volume or concentrationof contaminants in soil or groundwater overtime.2Carcass decomposition also generatesmethane, an explosive gas which can migratethrough the soil to enclosed spaces such assheds and houses, where it can replace theair and create an asphyxiation hazard or accumulate to explosive concentrations in thepresence of a spark or flame. Methane isalso a greenhouse gas, which contributes toglobal climate change. Despite these risks,burial has been historically used for mortality management and is familiar to mostpeople.Trenches and pits are the two most commonly used on-site burial methods. Trenchesare much longer than they are wide, whereaspits have a length which is more proportional to width. The photo below shows a typicalburial pit. FAO/Eran RaizmanScopeDeep burial pit
NO. 13 OCT 2018Table 1 highlights the major advantagesand disadvantages of deep burial. A morecomprehensive comparison of the disposaloptions is presented in the section "comparison of options" on page 4.Above-ground burialAbove-ground burial is a hybrid of deep burialand composting. As with deep burial, aboveground burial involves the disposal of animal carcasses within a trench excavated onthe farm. However, the above-ground burialtrench is much shallower than the trenchfor deep burial and includes a base of a carbonaceous material such as straw or woodchips. The trenches are designed to increasemicrobial activity and minimize the potentialfor groundwater contamination from carcassleachate.Above-ground burial includes a shallowtrench excavated into native soil to a depthof 60 centimeters (cm) (see Figure 2 and theaccompanying photo). Thirty cm of carbonaceous material is placed in the bottom ofthe trench followed by a single layer of animal carcasses. Excavated soils are subsequently placed back in the trench, forming amound on which the vegetative cap is established. For the vegetative cap, a plant speciesshould be selected that is readily availableand both regionally and seasonally appropriate. Finally, the perimeter of the mound istrenched to prevent the intrusion of surfacewater into the system. Once the carcasseshave decomposed, the disposal site can beleveled and returned to its previous use. Inmost environments this will take between 9and 12 months.Table 2 highlights the major advantagesand disadvantages of above-ground burial. Amore comprehensive comparison of the disposal options is presented in the section entitled Comparison of Options.Table 1DEEP BURIAL ADVANTAGES AND derations On-farm Public health risk Easy toimplement Biosecurity riskFastLow cost Burial may be viablefor small numbers ofanimals in suitable soils,but it is site-specific Pathogens may survive Not sustainable Regulatory limitations Limits future land use Requires heavy equipment orexcessive labourFigure 2ABOVE-GROUND BURIAL SCHEMATICSource: Gary FloryOpen burning (see photo on page 4) is aprocess which involves constructing a bedof combustible materials such as woodentimbers, placing the carcasses on the bed,adding more combustible material over thecarcasses, and igniting the pile. There is nocontainment of materials in this process.Historically, open or uncontrolled burninghas been used to thermally destroy animalcarcasses and associated materials duringanimal health crises. Open burning may betermed uncontrolled burning because it haslittle opportunity for inputs and outputs to Gary FloryBurningAbove-ground burialbe monitored or regulated. Neither the fuelnor air inputs can be reliably or accuratelycontrolled, which can result in incomplete,smoke-filled and relatively low-temperature combustion. The low-temperaturecombustion may not effectively inactivateall pathogens, and the significant air turbulence caused by the combustion process can3transport active pathogens by air, potentiallyspreading the pathogenic agent.Carcasses can be burned in open fields, oncombustible heaps called pyres, or with otherburning techniques that are unassisted by incineration equipment. Because of the significant air emissions and fire safety concerns,some governments specifically prohibit open
NO. 13 OCT 2018Table 2ABOVE-GROUND BURIAL ADVANTAGES AND derations Safe Pathogens may survive On-farm Scavengers may unearthcarcassesFastLow cost Innovativetechnologyundergoingfield trials andvalidation testing Readily available Fast to implement Public acceptance FAO EfficientOpen burningtemperature should rise to 57-60 C within 15days and then be maintained for several days.Intervention, such as turning the pile, may berequired to maintain the desired temperature.For intact large-animal carcasses, turning isnot recommended, and elevated-temperatureaerobic conditions should be maintained forweeks.In the curing phase, which occurs afterthe active phase, aeration is not as critical.During this period, a series of slow-rate reactions, such as the breakdown of lignin, occurat temperatures below 41 C. At the end of thecuring phase, internal temperatures withinthe compost pile range from 25-30 C.The material bulk density is reduced by25 percent and the finished product appearsdark brown to black and is free of unpleasantodours.For poultry composting, turning the pilecan speed decomposition; however, if the pileis constructed correctly, turning is not necessary and is not recommended within thefirst 14 days for infected carcasses. Largeranimals should not be turned before 30 days.Table 4 highlights the major advantagesand disadvantages of composting. A morecomprehensive comparison of the disposaloptions is presented in the section entitledComparison of Options.Comparison of OptionsTable 3OPEN BURNING ADVANTAGES AND derations On-farm Biosecurity risk Inactivatespathogens Not sustainableSlowExpensive Open burningposes risk ofcreating wildfires Reduces volume Inefficient Public opposition Air quality Smell Difficult to operate Regulatory limitationsburning of carcasses; government regulations should always be checked before deciding to use this method.Table 3 highlights the major advantagesand disadvantages of open burning. A morecomprehensive comparison of all the disposal options is presented in the section entitledComparison of Options.CompostingCarcass composting (see photo on page 5) isa process that involves constructing a porousbase layer of carbon material such as woodchips, mixing or layering carcasses with carbon material for the core of the windrow, andcapping the mixture with a blanket of carbonmaterial to promote decomposition of carcasses at elevated temperatures. Carcasscomposting consists of two phases: an activephase and a curing phase.The active phase is characterized by aerobic reactions at relatively high temperaturesresulting in a large reduction in the volumeof biodegradable solids. This phase has thepotential to produce significant odours whichare controlled by the carbon cap. Core pile4In the previous sections, each option wasdescribed and its major advantages and disadvantages were outlined. This section willcompare the various options to each otheragainst a number of criteria (see Table 5,Disposal Options Matrix). As can be seen inTable 5, the first column lists the criteria andsubsequent columns represent the disposaloptions. There are three sets of rows representing the most important criteria, whichwere weighted three times more than theleast important criteria, and the moderatelyimportant criteria, which were weighted twotimes more than the least important criteria.The discussion following the table containsadditional information for each criterion. Thenumbers shown in each box in the matrix represent the rating for each criterion as it relates to each option. A higher numerical rating indicates a more preferable option. Notethat the ratings are subjective, based on thejudgment of the authors and subject to interpretation by the user. When the numericalratings for each option are weighted based ontheir importance, totaled, and divided by thenumber of applicable criteria, the average
Gary FloryNO. 13 OCT 2018CompostingTable 4COMPOSTING ADVANTAGES AND derations Safe Time to completeSlowExpensive Requiresknowledgable/experiencedoperator toensure properconstruction Sustainable On-farm Easy to implementTable 5DISPOSAL OPTIONS rning1. Public health risk96362. Biosecurity66333. Pathogen inactivation93364. Environmentallysustainable96335. Volume reduction44466. Availability44627. Throughput66648. Speed to implement66469. Public acceptance444210. Cost-effectiveness233111. Efficiency122112. Operability1232Total Points61524442Average Score5444WeightingMost Important(x3)Important(x2)Less Important(x1)Criteria5scores can be compared to determine therelative ranking of the various options. Thedisposal options are listed from left to rightin the table in order of preference, based onthe average numerical ranking. Red indicatesa less favourable score, yellow a moderatescore, and green the most favourable score.Public health risk (Row 1) - The public health risk rankings in this table wereadapted from the United Kingdom (UK)Department of Health (now the Departmentfor Environment, Food and Rural Affairs)document entitled “A Rapid QualitativeAssessment of Possible Risks to PublicHealth from Current Foot & Mouth DisposalOptions, Main Report,” published in June2001. The UK assessment evaluated all risksto human health by all exposure pathwaysfor burning and burial of foot and mouthdisease-infected carcasses, as well as rendering, landfill and incineration. The healthrisks included bacteria, prions, chemical contaminants and airborne particles.Exposure pathways included drinking water,swimming, fishing, inhalation, direct contact, and consumption of crops and shellfish.Composting and above-ground burial technologies were not readily available at thattime, so the authors gave qualitative rankings to the newer technologies in accordancewith the UK criteria. The UK evaluation andthe authors found that composting was thesafest option, while above-ground burial andburning were safer than deep burial.Biosecurity (Row 2) - The level of biosecurity provided by each carcass management option was determined to be high if the carcassmanagement area could be contained andeasily disinfected (base rating of 3 points). Ifthe carcass management area was somewhatcontained but was difficult to disinfect, suchas a compost pile or above-ground burial plotthat has an absorbent layer beneath the carcasses which serves to minimize movementof liquids, the option was given a base ratingof 2 points. If the carcass management areacould not be contained, it was given a baserating of 1 point. Therefore, composting andabove-ground burial ranked higher than deepburial and burning.Pathogen Inactivation (Row 3) - If the carcass management option completely inactivates pathogens, it was given a high rating of3 points; partial inactivation received a ratingof 2 points; and no inactivation a rating of 1point. Therefore, composting ranked highest because it reaches high temperatureswhile the carcasses are fully enclosed, open
burning ranked medium because there issignificant air turbulence of partially heatedparticles which could spread pathogens, andabove-ground and deep burial ranked lowestbecause there is no heat generated to inactivate pathogens.Environmental sustainability (Row 4) –Environmental sustainability is defined as acarcass management option with a low riskof environmental contamination and a useful end product; such options were given abase rating of 3. Those options with a lowrisk of contamination or a useful end product were given a base rating of 2. Those options with a risk of environmental contamination and no useful end product were givena base rating of 1. Composting was rankedhighest because it minimizes environmentalimpacts while providing a soil amendment.Above-ground burial was ranked moderatebecause it reduces environmental impactsbut provides no useful end product. Deepburial and open burning were ranked lowest because they pose relatively high environmental risks and provide no beneficialby-products.Volume reduction (Row 5) - This factor relates to the ability of the process to reducethe volume of biomass. If the process reduces volume, it was given a base rating of 3; ifthe process resulted in the same volume, itwas given a base rating of 2; and if the process increases volume, it was given a baserating of 1. Open burning ranked highest forthis criterion because it was the only optionthat significantly reduces waste volume. Theother three options were ranked moderatelybecause they neither reduced nor increasedwaste volume.Availability (Row 6) – Availability is theability to acquire all needed inputs to theprocess. For example, if there is no landavailable for burying and no way to excavatetrenches, then burial would not be readilyavailable. Similarly, if there are no composting experts or carbon material such as woodchips available, then composting would havelow availability. For burning, open land andfuel sources could limit availability. If the inputs to the process are widely available, itwas given a base rating of 3; if the inputsare regional or somewhat available, it wasgiven a base rating of 2; and if inputs arevery limited in availability, the base ratingwas 1. Deep burial was ranked highest ofthe options because it is readily understoodand implemented. Above-ground burial andcomposting ranked moderately because Gary FloryNO. 13 OCT 2018Composting to control avian influenza: workers finalizing compost windrowsthey do not require specialized equipmentor material, but they do require specializedknowledge. Open burning was ranked lowest because it requires large amounts ofwood and fuel, and specialized expertise toperform safely.Throughput (Row 7) - For the purposes ofthis comparison matrix, throughput is defined as the amount of biomass that can beprocessed per day. If more than 90 metrictons of material can be processed per day,the base rating was 3; if the amount processed per day is between 23 and 90 metrictons, the base rating was 2; and if the method can process less than 23 metric tons perday, it was given a base rating of 1. All theoptions ranked highly for throughput exceptopen burning, which can take considerabletime to heat carcasses sufficiently to reducethem to ash.Speed to implement (Row 8) - This criterion refers to the amount of time it takes forthe process to receive the first carcasses,including obtaining government permissionif needed. Options that could process carcasses immediately received a base ratingof 3; options that could process the first carcasses in five days or less received a baserating of 2; and options that took more thanfive days to process the first carcasses received a base rating of 1. All the optionsranked highly in this category except deepburial, which requires procuring excavationequipment and digging the trenches, whichcan take some time.Public acceptance (Row 9) - This criterionrefers to the likelihood that the communitywill have a positive perception of the carcass6management option. Options likely to beviewed positively were given a base rating of3; those likely to be viewed as neither positivenor negative were given a base rating of 2; andthose options likely to be viewed negativelywere given a base rating of 1. Composting,above-ground burial and deep burial wererated more highly than open burning, which islikely to be viewed negatively.Cost-effectiveness (Row 10) - In this context, cost-effectiveness refers to the relative cost of a carcass management option.Relatively inexpensive options were given abase rating of 3; options with average costswere given a base rating of 2; and relativelyexpensive options were given a base rating of1. Above-ground burial and deep burial wererated the least expensive, composting wasrated moderately expensive, and burning wasrated most expensive because of the need forlarge quantities of fuel, labour and time.Efficiency (Row 11) - Efficiency refers tothe relative amount of inputs (utilities, chemicals, fuel, carbon source) to contain and stabilize biomass over a short period of time.Options with low input requirements weregiven a base rating of 3; options with moderate input requirements were given a base rating of 2; and those options with relatively highinput requirements were given a base ratingof 1. Above-ground burial and deep burialwere rated more efficient than compostingand burning based on the length of time toimplement and the need for fuel and carbonsource.Operability (Row 12) - This criterion refersto ease of implementation. For example, ifthe option is simple to do and operators are
NO. 13 OCT 2018ExampleThe example that follows illustrates howcarcass management concepts can be applied to an actual situation. Whether a farmraises poultry that become infected withavian influenza, swine affected by AfricanSwine Fever, or cattle affected by LumpySkin Disease, a similar approach can beused in all cases. These diseases, as wellas others, can cause illness or death in animals and sometimes humans, so the diseases must be contained to protect publichealth and the food supply. It is importantto respond to these outbreaks in a way thatminimizes losses to the farmer, protectsthem from disease or other health impacts,and protects surrounding farms from infection. Table 5 will be used in this example tohelp with the decision-making process. Itwill be assumed that (5,000) 2.3 kilogram(kg) birds weigh the same as (128) 90 kg pigsor (25) 454 kg cows, for a total of 11,340 kgs,or about 11 metric tons of infected material that must be managed, regardless of thespecies or disease.It is assumed there is a 10 hectare rural farm that raises 128 pigs. An averagepig weighs 90 kg. The pigs are infected withAfrican Swine Fever and must be destroyedto prevent spread to neighbouring farms. Thenext paragraphs discuss how each disposaloption might be used in this case.Starting with the matrix shown in Table 5,composting was the highest-ranked disposal option, so the first step is to determineif composting can be implemented at thisfarm. USDA has developed a tool based onthe matrix that includes a checklist to determine if the carcass management optioncan be used at a site. The checklist includesconsiderations for adequate space to buildthe compost pile, and sufficient distance todrinking-water sources, such as groundwater, neighbours, environmentally sensitiveareas, and utility lines. The site should nothave standing water and should be on a gentle slope.Because the example farm has 10 hectares of land and the compost pile for 128pigs would require about 43 square meters(0.004 hectares) (USDA calculator), there issufficient space to compost. Soil at the farmis assumed to be sand underlain by limestone, with groundwater less than 10 metersbelow the ground surface in the sand layer.An Iowa State University study found thatcompost piles can discharge leachate 1-2meters below the ground surface in certainsoils, so there will likely be several metersof unaffected soil beneath the compost piles,which is likely to be protective of groundwater. It will be important to place the compostpile at least 60-80 meters away from homes,streams or waterways, and drinking-waterwells. Selection of the compost site shouldtake into account convenience to the locationof the livestock in order to minimize movement of infected animals.Based on the above considerations, thesite appears to be suitable for composting.Next, it is necessary to determine whethertrained personnel are available to overseecompost pile construction and periodically monitor it for at least three months toensure that it becomes hot enough to inactivate pathogens, but not hot enough tocombust. During this time, troubleshooting, including pest management, may berequired. Heavy equipment, such as a skidsteer loader, will greatly simplify and speedthe process, which will otherwise have to beimplemented manually.Assuming trained personnel and any necessary equipment are available, it will benecessary to determine whether there isa readily available source of carbonaceousmaterial, such as wood chips, sawdust,rice or wheat hulls, or similar materials.Approximately 2 kg of carbon material areneeded per each kg of carcasses; therefore,about 22,000 kg, or 22 metric tons, of carbonmaterial will be needed. A compost thermometer will be very helpful to the process.In addition, strict biosecurity measures,including personal protective equipmentsuch as coveralls and respirators, will benecessary.When composting infected carcasses,pathogens can be spread if the piles aretoo close to groundwater or surface water,if the piles are not properly constructed, ifthey don’t become hot enough to inactivatepathogens, or if they are exposed tissueattracts vectors such as flies, birds, rodents or other mammals. Therefore, havingtrained personnel is critical to the successof composting.If responders wish to consider other options in addition to composting, and referringback to the matrix in Table 5, the next best option is above-ground burial.In order to implement above-ground burial, the same site conditions will be needed as for composting. Those conditionsare assumed to be met at this site, so thenext consideration is access to trainedpersonnel, and any needed materials and Gary Floryreadily trained and available, then it is ratedhighly operable with a base rating of 3. If theoption is simple to do or operators are readily available, then it is given a base rating of2. If the option is difficult to implement andtrained operators are scarce, then it is givena base rating of 1. Deep burial was rated easiest, with readily available operators; aboveground burial and burning were rated moderately operable; and composting was ratedleast operable because of the need for highlytrained composting experts.When taken together and viewed overall,the benefits of composting and above-groundburial outweigh the benefits of deep burialand burning, despite cost or any other singlecriterion. zBurial of cows7
NO. 13 OCT 2018Conclusions/Recommendations Gary FloryComposting, above-ground burial, deepburial and burning are suitable options forcarcass management at small farms thathave limited access to engineered landfills,rendering plants or controlled incinerators. In general, composting has more advantages than above-ground burial, whichhas more advantages than deep burial andburning. However, multiple options may besafely implemented depending on specificsite conditions. Since calculations and dataare required to determine if site conditionsare suitable for a specific method, planningin advance can greatly expedite a response ifan outbreak occurs. zBurial of swineequipment. Trained personnel are ideal forabove-ground burial. However, this processcan be successful if untrained personnelclosely follow a written protocol. Sufficientcarbon material for a 30 cm layer at the bottom of the trench will also be needed. Basedon USDA calculations, approximately 154square meters will be required for 128 pigs.If wood chips weigh about 314 kg per cubicmeter, then approximately 14,500 kg of woodchips or similar material will be required.As with composting, heavy equipment, if itis available, would facilitate above-groundburial.Risks of above-ground burial would arisefrom insufficient cover over the carcasses, which would attract vectors that mightspread pathogens. Another risk would berelated to constructing the above-groundburial plots in areas where groundwater isless than a meter below ground surface.In that case, leachate may pose a risk togroundwater, especially if the soils arehighly permeable, like sand.Deep burial is the next best option inthe matrix in Table 5. Based on the USDAchecklist, the first step when consideringdeep burial is to consider the suitability ofthe soil. Our example site has sand, whichis relatively p
Carcass management can be performed onsite or offsite by a variety of methods; the selected method depends on the specific site conditions, including locally available re-sources and type and size of operation. z Carcass management for small- and medium-scale livestock farms Practical considerations 1 Introduction 2 Approaches to Carcass .
