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Livestock Mortality Composting

Laura K. Snell, Livestock and Natural Resources Advisor and County Director, Modoc County Nicole Stevens, Lab Assistant, Siskiyou County



When a large animal dies on your farm or ranch, what are your options for disposal? In California, there are limited legal options especially as rendering facilities have closed, regulatory burden has increased, and predator populations have grown. Livestock Mortality Composting could be a viable solution. Composting of mammalian tissue is legal in most states and recommended for on-farm disposal of livestock mortalities. California has allowed composting to occur on farms only during emergency situations such as high heat events, natural disasters, and disease outbreak. It is time composting becomes a legal disposal option for livestock mortalities, including getting all the regulatory agencies at the table to streamline the process.


California has one of the strictest composting requirements in the country - requiring yard waste, food scraps, and more be sent to composting facilities so why are we so behind on livestock mortality composting? With livestock and dairy production contributing $11.7 billion in 2018 (CDFA) to the state economy, change is needed to support these industries. There are currently three rendering facilities statewide located in central California between Sacramento and Fresno. In many cases these facilities are too far from livestock operations to take mortalities and the cost to transport and process carcasses is prohibitive to operations. Transporting a mortality off farm is required to be done by a licensed dead animal hauler. Rendering provides a beneficial use to the carcass like composting and unlike other disposal options. Landfills can get permitted to accept livestock mortalities but there is no beneficial use to the carcass and not many landfills are properly suited. Many livestock operations have a “bone pile” where they are placing livestock mortalities. This option can attract large predators such as wolves, mountain lions, bears and others making it a hazard for livestock operations with decreased predator control options. It also increases the time needed for the mortality to decompose.


In 2019, a team of UCCE and CSU Chico researchers began a study looking at how livestock mortality composting would work in California. What are the current regulations preventing composting? Have studies taken place in the past? What would a composting site look like that follows current state regulations? Are all these regulations needed? All these questions led to a composting site being established at the Intermountain Research and Extension Center in Tulelake, CA. Letters and permits were submitted to agency staff from the county environmental health department, CalRecycle, CDFA, CA State Veterinarian, and the regional and state water board.



An existing 3-sided structure with cement at the base was retrofitted to accommodate the permitting regulations for the composting pile. A metal roofed carport structure was installed within the structure as a roof, required by the regional water quality board. Base rock material was placed on the floor and a pond liner was put on top of the rock to act as an impermeable layer. Then tube sand was used to secure the pond liner and created a basin to deter any run off from the site.


Livestock mortalities that have died only of natural causes are allowed to be composted. On August 10th we received a call that a cow was available for our project from a local producer. We were required to have a certified dead animal hauler move the animal. Once at the composting site, a layered base of fine and course wood chips and straw  was laid out as an absorptive layer on top of the base rock. The carcass was placed in the center of the structure on top the layered base materials. Once the carcass was positioned carbon materials were layered on top. These materials included straw, fine wood chips and course wood chips. Materials were by-products from the Alturas Mill.. A sprinkler is available to add moisture as needed during the study.



Temperature readings are taken daily at 18 and 36 inches and moisture and pH are taken once per week. A temperature of 131 degrees Fahrenheit for 72 hours is required to kill potential pathogens in the compost pile. On day three, the pile achieved the target temperature and continued through day eight. Water is applied as needed and extra wood chips and straw are available as the pile shifts and needs extra material. There is a good amount of research and educational material about livestock mortality composting from several university cooperative extension programs across the country. Washington State University did a webinar recently on composting that was extremely informative. If you are interested, to watch the video online you can find it here. Navigating the regulatory process and coordinating with 8-10 government agencies with competing regulations makes this process unfeasible currently in California. By the end of this study, our objective will be to suggest best management practices from our research and other available science to create a streamlined approach to livestock mortality composting in California.


Big thank you to Carissa Koopman Rivers who started this project in 2018, Dr. Kasey DeAtley at Chico State for her brilliance in study design and expertise, and the city of Alturas for carbon materials. We would also like to thank our local producer for the livestock mortality and the Intermountain Research and Extension Center for their patience and monitoring help.


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