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NM-1422

July 2009

North Dakota State UniversityFargo, North Dakota 58108

Animal CarcassDisposal Options

Shafiqur RahmanAssistant Professor, ExtensionWaste Management Engineer,North Dakota State University

Teresa DvorakArea Livestock NutrientManagement Specialist,North Dakota State University

Charles StoltenowAssociate Professor,Extension Veterinarian,North Dakota State University

Saqib MukhtarAssociate Professor,Texas AgriLife Extension,Texas A&M Systems

Animal mortality losses are anormal part of livestock andpoultry production facilities.Producers may have losses due todisease, accidents, inter-animalcompetition or natural disasterssuch as flooding. They need tothink about mortality manage-ment before a death occurs toavoid having problems afterthe fact.

The producer is responsible fordisposing of these mortalitieswithin 48 hours in an environ-mentally acceptable manner.Safe disposal of carcasses is animportant issue for day-to-day,routine management of livestockand poultry mortalities to preventdisease transmission and toprotect air and water quality.Therefore, carcass disposalremains one of the majorproblems facing livestockand poultry producers.

Owners and operators of animalfeeding operations (AFOs) haveseveral options for disposingmortalities, including rendering,incineration, burial andcomposting. Each option has a setof advantages and disadvantagesthat must be considered duringplanning for and prior tomortality disposal.

Producers must take specialprecautions with the disposal ofdiseased animals because statesmay have stricter and differentmortality handling and disposalrequirements pertaining to certaininfectious diseases.

The following is a briefdiscussion of each disposaloption. Contacting your localregulatory agency to determinewhat regulatory requirementsmay need to be met beforeadopting any of the followingoptions also is helpful.

Rendering • Incineration • Burial • Composting

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RenderingRendering is the process ofconverting animal carcasses intopathogen-free, useful by-productssuch a feed protein. In the processof rendering, the carcasses areexposed to high temperatures(about 130 degrees Celsius or265 degrees Fahrenheit) usingpressurized steam to ensuredestruction of most pathogens.However, rendering posesbiosecurity concerns due totransportation of livestockmortalities to multiple locationsen route to the rendering plant(Fonstad et al., 2003).

The rendering market haschanged in recent years as theprice of meat and bone meal hasdecreased and the use of manyrendered byproducts has beeneliminated due to concernsrelated to transmissible bovinespongiform encephalopathies(BSE or mad cow disease).Since 2005, cattle infection withthe BSE disease has had a highlynegative impact on the industry.

The new Food and DrugAdministration (FDA) rule(effective April 27, 2009) thatrequires removal of the brainand spinal cord of all cattleage 30 months or older makesrendering animal carcasses harderand more expensive. This newFDA regulation is aimed atprotecting against transmissionof BSE, but rendering facilitiescharge additional fees for thenew processing requirement.

In addition, rendering might notbe an option for some producers,depending on location, type and

volume of mortalities. In NorthDakota, in the case of anyinfectious or contagious disease,a carcass must be disposed ofwithin 36 hours or transferredto a licensed rendering plant.However, large distances betweenrural areas and rendering plantsand lack of timely pickup serviceof dead animals from farms arethe biggest challenges for usingrendering as a mortality disposalmethod. In many areas, thenumbers of rendering facilitiesare limited and in many casesare declining due to increasedcosts and biosecurity risksassociated with transportingmortalities (Glanville et al., 2009).

IncinerationIncineration is the thermaldestruction of carcasses byauxiliary fuel such as propane,diesel or natural gas. Modernincinerators reduce carcasses toash and generally are biosecure.Incineration requires a great dealof energy compared with otherdisposal methods and is notconsidered a viable economicdisposal option due to costand labor.

Incineration is a preferred methodfor managing small carcasses(for example, poultry and swine),but often large carcasses and/ora large number of mortalitiescannot be handled due to thesmall incineration capacities(mostly limited to less than300 pounds per head) of moston-site farm incinerators.

In Texas, poultry carcassincineration is a common method

of managing routine poultrymortality (Fig. 1) because burialof dead birds is prohibited unlesstheir numbers exceed 0.3 percentper day of the total farm inven-tory (Mukhtar et al., 2008).

The capital cost of incinerationmay be a limiting factor forsome producers, but poultryand small-livestock producersmay find incineration to be aconvenient option to disposeof mortalities as they aregenerated, eliminating theneed for temporary storage.However, regular cleaning andmaintenance are required tokeep the incinerator functioningproperly. Also, incineratorsmust be loaded and operatedaccording to the manufacturer’srecommendations. Odor nuisancecomplaints generated due to apoorly functioning incineratorare common.

Burning carcasses in a pit onsite is an acceptable methodof disposal in North Dakota.Open-pit or open-pile burningshould be a method of last resort.Consider personnel and propertysafety and choose a properlocation away from the publicview. Refer to the “Burial” sectionon choosing an appropriatelocation. Be sure the carcass isburned as soon as it is discoveredand it burns completely.

North Dakota state law requiresanthrax-infected carcasses beincinerated or buried (at least6 feet deep) on the same sitewhere they died if possible. Hogsthat have died from hog choleraor swine erysipelas also must beburned on site within 36 hours.

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Fig. 1. Incinerator for managing poultry carcasses.

BurialBurial is a common method ofcarcass disposal to managemortalities, but it poses a ground-water contamination risk if theburial site is not selected andmanaged properly. Therefore,selection and maintenance ofa burial site is very important.For example, areas with sandyor gravelly soil and a shallowground water table must not beused as burial sites. In NorthDakota, the bottom of the dis-posal trench must be 4 feet aboveany permanent water table, andthe trench must be a minimumhorizontal distance of 200 feetfrom the nearest surface water.

Also, the disposal site shouldbe away from any residence,drinking water well, shallowaquifers or areas that may beflooded. Often, excessive

pollutants can build up in burialsites and leaching of nitrogen andphosphorus into water bodiescauses eutrophication (Turanet al., 2007). From a biosecuritypoint of view, burial is a viableoption. But the challenges ofdisposal by burial may includeidentifying suitable on-farmburial sites due to the risk ofground water contamination.

Prompt burial will preventnuisance problems such as odors,flies and scavengers. On-farmburial might be the quickest wayto dispose of nondiseased animalmortalities. The disposal trenchbottom should be compactedand mortalities should be placedin 3-feet to 4-feet layers in thedisposal trench. A layer of 6 to12 inches of soil can be placedbetween layers of carcasses.The trench should be covered

with soil mounded to shed rain-water, and the mound should beinspected periodically for settlingor caving. Anyone burying deadlivestock needs to take personneland equipment safety precautionsduring trench digging, carcasshandling, placing carcasses in thetrench and backfilling the trenchwith soil.

Burial is difficult during winterand not an option during floodingor in areas prone to flooding.Livestock owners may find thatdigging a long trench in thesummer for animal carcass burialduring winter is economicallyadvantageous since excavationof frozen soil may be impossible.

A dead animal may be placed atone end of the trench and coveredwith soil. When another carcassneeds to be added, the carcasscan be placed in the trenchimmediately and covered evenif the ground is frozen. Livestockowners need to take properprecautions, such as fencing thetrenched area, with this systemsince an open trench can be asafety hazard.

CompostingComposting is a naturallyoccurring process in which thedead animal is broken down intobasic elements (organic matter)by microorganisms, bacteriaand fungi. Composting hasadvantages over other methodsof carcass disposal, includinglower costs, easy-to-prepare pilesand windrows with availableon-farm machinery, and lowerrisk of air and water pollution.

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Fig. 2. Bins arranged for sow and litter composting. Additionalspace is for co-composting material storage and handling.

Composting has gainedpopularity in areas where burialand incineration are not practicalor have become restricted.Proper composting techniqueswill destroy most disease-causingbacteria and viruses. Compostingof carcasses is recognized asan effective method by thebiosecurity agencies in theU.S. and other countries tomanage routine and emergencymanagement of mortalities(Wilkinson, 2007).

Composting is the preferredmethod of carcass disposal sinceit can be implemented rapidlyon farms at minimum cost.However, selection of a propercomposting site is important toprevent surface water runoff tothe compost site and runoff ofleachate from the compost site,as well as leaching of raw orfinished compost nutrients toground water.

Similarly, proper maintenanceof compost piles or windrows(for example, temperaturebetween 90 and 140 F, moistureranges between 50 percent and60 percent on a wet basis,carbon-to-nitrogen ratio rangesbetween 20:1 and 25:1, turning,etc.) is required to avoidanaerobic conditions duringthe composting process thatcan contribute to odor issuesand greenhouse gas emissions,including methane (CH4) andnitrous oxide (N2O) (Hao et al.,2001; Xu et al., 2007).

Procedures forcarcass compostingCarcass composting typicallyis done in one of three primaryfacility types: a bin, a staticwindrow or a minicomposter(Keener et al., 2000). Each ofthese options is describedbriefly in the following sections.

Bin Composting: Small andmedium-sized carcasses can becomposted in a three-sidedenclosure (for example, a bin)constructed on compacted claysoil or a concrete floor (Fig. 2).At least three bins are usually inoperation at any time. As one binis being filled, another is in theprimary stages of compostingand the third is in the secondarystages (secondary heat cycle)of composting.

A base of sawdust, poultry litteror other suitable carbon source12 to 18 inches in depth isrequired depending on carcasssize. Suitable carbon sources vary,but may include straw, wastefeed/hay, sawdust, poultry litteror finished compost. The bulkingmaterial, such as cornstalks andtree trimmings, needs to provideporosity and structure to acompost pile; therefore, manureis not the ideal choice. Manuremay be used if enough beddingis incorporated with it.

Carcasses are layered in the binwith a suitable carbon sourcebetween each layer. Make sureno part of a carcass is exposed;otherwise, predators will beattracted to the site. Typically, aminimum 12- to 16-inch layer of

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co-composting material aroundall sides of the carcass will dis-courage predators, control odorsand eliminate flies. As a generalguide, 3 to 5 cubic yards of co-composting material is requiredfor every 1,000 pounds of carcass(Auvermann et al., 2006).

Materials are turned usinga bucket loader. The turningoperation mixes the compostingmaterials and enhances passiveaeration. Typically, turningfrequency should be based onpile temperature and turningshould occur when the compostpile temperature exceeds 140 For drops below 90 F.

Pile or Windrow composting:A conventional pile and windrowcomposting system is a bettermethod for large animals (forexample, mature cattle or pigs).Piles and windrows for mortalitycomposting usually areconstructed in the open on acompacted soil (for example, claysoil) or a concrete floor to controlwater infiltration. In pile orwindrow composting, typicallywalls and roofs are not used toease access for loading, unloadingand mixing of the pile or wind-row from all sides (Fig. 3, page 6).

Windrows are aerated primarilyvia natural air movement orpassive air movement (Rynk,1992). A conventional compostingpile is managed vigorously in thebeginning to maintain aerobic andthermophilic conditions (greaterthan 105 F) to encourage rapidrates of decomposition, elimina-tion of objectionable odors, andthe destruction of pathogens andweed seeds (Wilkinson, 2007).

However, during mortalitycomposting, piles are leftundisturbed during the firststage of composting (phase I) toensure soft tissue is decomposingproperly.

For small- and medium-sizedcarcasses (for example,poultry, pigs, sheep) the activecomposting period (phase I) maybe up to three months before thepile is turned (Keener et al., 2000).However, for a large carcass(mature beef and dairy cattle,horses or other large animals),the active composting phase maybe up to six months (Auvermann,2006). Following the activecomposting phase, additionaltime (days to weeks, dependingon composting conditions)may be needed for small-and medium-sized carcassesto complete decomposition(phase II), while large carcassesmay require months.

Turning the pile mixes thematerials and rebuilds theporosity of the windrow.However, frequent turning ofan active compost pile duringa disease outbreak may increasethe risk of generation and releaseof airborne particulates thatcan carry infectious microbes(Xu et al., 2009). Small-scaleturning typically is done by afrontend loader or bucket loader,but large-scale turning is done bya tractor-assisted windrow turner.

Small and medium-sized car-casses can be placed in layersin windrows, but large carcasses(for example, cattle, horses) needto be placed in a single layer(Fig. 3). Place the mortality on

the co-composting material andcover the mortality with another1 to 2 feet of co-compostingmaterial. The co-compostingmaterial may settle or bedisturbed by wind, so be sureto check the pile periodically.If you notice excessive odors,add more co-composting materialto the outside of the pile.Due to placement and handlinglimitations of large carcasses,composting may not be practicalto consider during a massiveinfectious disease outbreak.

Often, during the carcasscomposting process, liquid maydrain from the composting pile,which needs to be contained.A dry and absorbent basematerial (for example, hay orstraw, finished compost, sawdust)can be used to capture liquiddraining from the compostingpile (Auvermann, 2006).

Placing a fresh (warm) carcassin a compost pile will helpspeed the decomposition processversus placing a cold carcass inthe pile. Also, starting a freshcompost pile in the winter willadd significantly to the timeneeded to finish compostinga large carcass because of theadditional time the microorgan-isms will take to produce ad-equate heat.

Minicomposters: Minicompostersare used for small-carcass(for example, poultry)composting and are not suitableto handle large volumes ofanimal mortalities. For a northernclimate, additional insulationmight be required to reach

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(a) (b)

(c) (d)

Fig. 3. Photos showing the composting pile construction procedure: (a) placing liner;(b) breaking up a round straw bale, (c) laying the straw base and measuring the perimeterafter laying carcass, (d) finishing the pile with adequate straw surrounding the carcass.

(Source: Ying Chen, University of Manitoba)

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desired temperatures forpathogen destruction andeffective degradation (Keeneret al., 2000). Also, highercapital investment is required.

Overall, a major advantage ofcomposting is that the finalproduct can be used as a nutrientsource on fields, but propermanagement is needed.

SummaryProducers have several optionsfor disposing of carcasses, includ-ing rendering, incineration, burialand composting. The choice ofdisposal options depends onlocation, availability of rawmaterials or equipment andservices, affordability andlimitations to properlyprotecting the environment.

Carcass composting is consideredone of the best disposal optionsdue to its greater affordability,better biosecurity and low inputsand investment requirements,but composting needs propermanagement for completedecomposition and to ensurethat objectionable odors are notgenerated. Complete destructionof pathogens and weed seedsoccur by maintaining thermo-philic conditions during theactive composting period.

If done properly, compostinganimal carcasses is an environ-mentally safe disposal option tomanage emergency mortalitiesthat do not require very hightemperatures for completedestruction of transmissiblediseases such as BSE.

ReferencesAuvermann, B., Mukhtar, S., and Heflin,

K. 2006. Composting large animalcarcasses. Texas CooperativeExtension Bulletin, The TexasA&M University System, E-422

Fonstad, T.A., Meier, D.E., Ingram, L.J.,and Leonard, J. 2003. Evaluation anddemonstration of composting as anoption for dead animal managementin Saskatchewan. Canadian BiosystemsEngineering. 45: 6.19 - 6.25.

Glanville, T.D., Ahn, H.K., Richard, T.L.,Shiers, L.E., and Harmon, J.D. 2009.Soil contamination caused byemergency bio-reduction ofcatastrophic livestock mortalities.Water Air Soil Pollution. 198: 285-295.

Hao, X., Chang, C., Larney, F.J., andTravis, G.R. 2001. Greenhouse gasemissions during cattle feedlotmanure composting. Journal ofEnvironmental Quality. 30: 376-386.

Keener, H.M., Elwell, D.L., and Monnin,M.J. 2000. Procedures and equationsfor sizing of structures and windrowsfor composting animal mortalities.Applied Engineering in Agriculture.16: 681-692.

Mukhtar, S., Nash, C., Harman, W., andPadia, R. 2008. How much does thatincinerator cost? AgriLife ExtensionBulletin, Texas A&M University,B-6209.

Rynk, R.F. 1992. On-farm compostinghandbook/editor: Robert Rynk [et al.].Ithaca, N.Y.: Northeast RegionalAgricultural Engineering Service(NARES).

Stoltenow, C.L., and Hammer, C.J. 2009.Anthrax. NDSU Extension publica-tion V561.

Turan, N.G., Akdemir, A., and Ergun,O.N. 2007. Emission of VolatileOrganic Compounds duringComposting of Poultry Litter[electronic resource]. Water, Air,and Soil Pollution. 184(1-4): 177-182.

Wilkinson, K.G. 2007. The biosecurityof on-farm mortality composting.Journal of Applied Microbiology. 102(3):609-618.

Xu, S., Hao, X., Stanford, K., McAllister,T., Larney, F.J., and Wang, J. 2007.Greenhouse gas emissions duringco-composting of calf mortalitieswith manure. Journal of EnvironmentalQuality. 36: 1914-1919.

Xu, W., Reuter, T., Inglis, G.D., Larney,F.J., Alexander, T.W., Guan, J.,Stanford, K., Xu, Y., and McAllister,T.A. 2009. A biosecure compostingsystem for disposal of cattle carcassesand manure following infectiousdisease outbreak. Journal ofEnvironmental Quality. 38: 437-450.

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