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Project in Detail
Background
Objectives
Composting System Tested
Research Methods
Preliminary Results
Project Sponsors & Contacts

Draft Guidelines for Emergency Cattle Mortality Composting

Link to  ISU Swine Mortality Composting Website

PROJECT EXECUTIVE SUMMARY

The following provides an overview of this project and its current status.  For information on specific aspects of the project, click on the links listed in the navigation bar along the left side of your browser window.

Project Title:  Environmental impact & biosecurity of composting for emergency disposal of livestock mortalities

Primary  Project Sponsor:  Iowa Department of Natural Resources with supplemental funding through the National Research Initiative of the U.S. Department of Agriculture.

Proposed Project Duration:  3 years (August, 2002 - June, 2005)

Objectives:

• Evaluate the feasibility of using composting for emergency on-farm disposal of livestock mortalities (particularly large animals such as cattle) in the event of a livestock disease outbreak or agro-terrorism in Iowa.

• Study the potential impacts of emergency livestock mortality composting on air quality, water quality, and soil quality.

• Investigate the potential of emergency animal mortality composting systems to retain and destroy pathogens thereby reducing or preventing the spread of disease.

Why Not Rely on Rendering and Burial?
In the wake of the 2001 Foot-and-Mouth Disease (FMD) outbreak in Great Britain, the Iowa Department of Natural Resources (IDNR) assessed the livestock disposal options if Iowa were to experience a similar emergency.  Their conclusions:

• As was the case in Great Britain in 2001, Iowa's rendering service facilities, and it's ability to rapidly transport large numbers of carcasses to these facilities, could be temporarily overwhelmed by a widespread animal disease outbreak.

• As much as 40% of Iowa has shallow ground water, shallow bedrock, or other environmentally sensitive conditions that make mass burial of livestock in these areas undesirable.

• Iowa does not have a large amount of enclosed high-temperature incineration capacity, and open incineration of animal carcasses would produce unacceptable air pollution as was the case in Great Britain.

With the above limitations in mind, and recognizing that composting is now being used by many swine producers for disposal of normal production mortalities, IDNR decided to commission a study of the feasibility and environmental impacts of using composting for emergency disposal of large carcasses.  Since cattle carcasses are among the largest and most difficult to dispose of, IDNR stipulated that the study evaluate the potential for composting cattle.

Study Design & Procedures

• System tested - simple "windrow" composting design that can be constructed quickly in an emergency using on-farm equipment and cover materials (for the purposes of this study it is assumed that there would be inadequate time to construct composting bins, roof, floor, etc.).

• Type of carcasses composted - cattle (purchased from rendering service) 1,000 lb average weight

• System loading - Four carcasses (4,000 lbs total) per test unit.  Carcasses are placed in a single layer (no stacking) to minimize potential for leachate release and excessive pile settling.

• Operation - No turning of windrows.  It is assumed that, in a true livestock disease  emergency, cattle carcasses would contain infectious organisms and turning would increase the potential for airborne disease transmission.

• Cover materials tested - Three different materials that are commonly available on cattle or dairy operations are being field tested: corn silage, ground cornstalks, and dry or moist manure capped with ground straw.

• Seasonal conditions - To evaluate year round performance, composting test units are constructed at three critical times of year.....hot/dry weather (summer), cold weather (winter), cool/wet weather (spring).

• Physical/chemical data collected from each test unit -   internal temperatures (@ 20 locations), oxygen profiles, soil quality (before and after composting), odor samples (weekly during 1st four weeks following construction).

• Virus inactivation data collected - Vaccine strains of two avian viruses (Newcastle Disease Virus, and avian encephalomyelitis) are placed into the composting test units in retrievable sample vessels. Samples are withdrawn on a time basis over a period of several weeks and tested for viability.

• Virus retention data collected - Summer time trials are seeded with two avian viruses at the time of construction.  Cages of pathogen-free sentinel poultry are placed within 10 feet of trials and blood samples from poultry are assayed for evidence of immune system response to the viruses.

Preliminary  Findings (as of March, 2004)

• Number of test units constructed to date - 21 (containing 42 tons of carcasses)   Note: total of 27 test units (3 cover materials X 3 seasons X 3 replications) will be constructed during the total project.

• Approximate decay time for 1,000 lb carcasses (un-turned) - Generally 8 -12 months or less under all weather conditions when using silage, ground cornstalks, or hay/manure.  Some trials begun during warm weather have taken less than 6 months.

• Cover material that produces quickest decay - The three cover materials that have been field tested appear to achieve complete carcass decay in about the same amount of time.

• Cover material with best potential to kill disease-causing organisms - Test units constructed with corn silage appear to have the best potential for killing pathogens.  Silage test units typically produce the highest core temperatures in the shortest amount of time following construction of the test units.  Internal temperatures within silage test units also tend to be more consistent throughout the pile, and persist longer than in test units constructed with ground cornstalks or hay/manure.

• Odor control -Preliminary threshold odor data indicate that odor in the immediate vicinity of the composting test units is very low and that, in many cases, odor from composting test units cannot be distinguished from the odors emanating from stockpiles of the cover material.

• Biosecurity - Vaccine strains of Newcastle Disease Virus survived fewer than 8 days during cool (late April) weather, and fewer than 3 days during warm (June) weather. Silage test units exhibited the shortest virus survival times during cool weather, but during warm weather the type of cover material did not greatly affect virus survival time.

System Performance

Soil & Water Impacts

Air Quality Impacts

Biosecurity