Ahb 506 - Animal Waste Production and Management Week – 8 - Disposal of carcasses

Week – 9 - Tutorial class questions 1. What are the four factors in the basis of selecting methods of carcass disposal? 2. What are the six methods of carcass disposal? Explain each method. 3. What is a Prion? Why is it that meat and bone meal from rendered ruminant carcasses are not advised to be feed to ruminant animals?

Disposal of carcasses Proper disposal of the animal carcasses and associated materials (e.g., bedding, manure) is necessary to ensure that animal disease does not spread. In some cases a variety of methods may be used for a more efficient and effective operation.

Disposal of carcasses Method selection will be based on a number of factors, including; the type and quantity of animals, the risk of disease spread, the health and safety of responders, the public and the environment.

Some of the possible disposal methods that may be used for animal disease emergencies are listed and briefly described below. Composting Rendering Burial Landfill Incineration/burning Alkaline Hydrolysis

Composting Is the controlled aerobic decomposition of raw organic material such as dead animals, manure, processing wastes, straw or stalks into a soil- like substance called compost. This method involves the above ground decomposition of animal carcass over a period of time.

Composting Composting may be done when soil conditions do not facilitate adequate burial procedures. The process can be complex and requires an appropriate site, proper management and the proper supplies (e.g., wood chips, sawdust and biosolids). The composting process and the natural decomposition of the animal serve to reduce the disease agents present.

Composting Compost makes an excellent soil amendment Composting Compost makes an excellent soil amendment. If done properly, composting produces enough heat to destroy any pathogens and weed seeds in the raw organic material. This is a process of aerobic microbiological decomposition conducted in either open or closed systems. It preferably requires prior grinding of tissues and as well the addition of organic material for microbial maintenance.

Composting Additionally, mixing or aeration is required to assure homogeneous decomposition. This simple process, which can be conducted on site at low cost, can achieve temperatures of up to 70o C. It does, however, require a significantly extended period of time. Further it is necessary to insure a constant temperature throughout the material for the total time period and it is difficult to verify the effectiveness of pathogen inactivation.

Rendering This is a closed system for mechanical and thermal treatment of animal tissues leading to stable, sterilized products, e.g animal fat and dried animal protein. It grinds the tissue and sterilizes it by heat under pressure.

The technology exists in fixed facilities and is in normal usage. Rendering is the most economical method of disposing of carcasses, however movement of infected carcasses to rendering plant locations, may pose some risk of disease spread, so preventive precautions must be taken.

Rendering Rendering produces an effective inactivation of all pathogens with the exception of prions where infectivity is reduced. A medium sized rendering plant could process 12 tonnes per hour of operation. The availability of the capacity should be determined in advance. Such plants can operate within environmental standards.

Rendering  is a process that converts waste animal tissue into stable, value added materials. Rendering can refer to any processing of animal products into more useful materials, or more narrowly to the rendering of whole animal fatty tissue into purified fats like lard or tallow. Rendering can be carried out on an industrial, farm, or kitchen scale.

The rendering process simultaneously dries the material and separates the fat from the bone and protein. A rendering process yields a fat commodity (yellow grease, choice white grease, bleachable fancy tallow, etc.) and a protein meal (meat and bone meal, poultry byproduct meal, etc.).

The rendering process varies from plant to plant in many ways. a. Whether the end products are to be used as human food is based on the type of raw material and the processing methods. b. Whether the end products are to be used as animal or pet food. c. The material may be processed wet or dry. In wet processing, either boiling water or steam is added to the material, causing fat to rise to the surface; in dry processing, fat is released by dehydrating the raw material. d. The temperature range used, whether high or low. e. Processing may be either in discrete batches or in a continuous process. f. The processing plant may be operated by an independent company that collects the material on the open market, or by the packing plant that produced the material.

BSE (Bovine Spongiform Encephalopathy) For many years meat and bone meal were fed to cattle. This practice is now prohibited in developed countries because it is believed to be the main route for the spread of  (mad-cow disease, BSE), which is also fatal to human beings. Meat and bone meal from cattle is, however, fed to non- ruminant animals and meat and bone meal from non- ruminant animals is fed to cattle in the United States This may not prove to be a solution to the problem due to the resistant nature of the infectious agent of BSE, a misfolded protein (prion). Therefore, even if cattle are fed to non-ruminant animals and vice versa, it will not prevent BSE from occurring. The underlying cause is that the prion survives within the system of the animal that has been fed with meat and bone meal from different animals including cattle. These animals are then eventually rendered and fed to cattle, which also results in the development of the disease.

Burial On-premises burial is one of the preferred methods of animal carcass disposal. Any burial action should be coordinated and comply with local regulations (LGU, Ministry of Health, Ministry of Environment and agriculture. Ensure that the selected site is away from water sources and public lands, has a steep slope greater than 15% and is in suitable soil.

Burial Listed below are some of the trench characteristics for animal carcass disposal. Fourteen square feet of surface area is needed to bury 1 cow carcass, or 5 pigs, or 5 sheep A trench 6 foot deep x 300 feet long x 10 ft wide (approximately 18,000 cubic feet) can hold approximately 360 horses, or 400 cows, or 2,100 pigs, or 3,900 sheep, or 30,000 turkeys, or 90,000 chickens Trenches should not be closer than 50 feet from another trench Trenches should be covered with 3 to 6 feet of cover soil below the natural contour to the top of the carcasses; this cover soil should not be compacted The Global Positioning System (GPS) of each burial site should be recorded A burial site must be inspected regularly after closure to detect seepage or other problems that may arise.

Landfill The use of landfills for carcass and material disposal may be an option. The necessary equipment, personnel, procedures and containment systems are already in place and may be useful. However, the transport of carcasses to these locations may pose some risk of disease spread.

Incineration/Burning This method of carcass disposal is difficult, expensive and resource intensive open burning of animal carcasses is not allowed in some places.

Alkaline Hydrolysis This process uses sodium hydroxide or potassium hydroxide under heat and pressure to digest carcass tissue. The resulting effluent typically has a pH level of 11.4 to 11.7, and in most cases, can be discharged into municipal sewage systems. The process does require specialized, expensive equipment therefore this method has limited application in a disease outbreak situation.

On-farm livestock mortality composting facility with wood walls and a fabric-covered hoop roof provides biosecurity without odor, rodents or scavengers.

Burning of FMD infected animals