California ranchers may soon have a new tool to manage livestock carcass disposal under a bill currently under consideration in the state legislature. Assembly Bill (AB) 411, the Caring About The Terrain, Livestock, and Ecosystems (C.A.T.T.L.E.) Act, would allow routine livestock mortalities to be composted on the owner’s land if strict best management practices are followed.
Under the bill, composting is only allowed if it takes place on land owned or leased by the owner of the deceased livestock and is limited to 100 cubic yards of material at a time. Carcasses must originate from the same or an adjacent county, and transportation must comply with state and local laws. The bill also defines which types of livestock qualify and excludes deaths involving barbiturates, reportable animal diseases or livestock under quarantine.
These practices, developed by the secretary of the California Department of Food and Agriculture in coordination with CalRecycle and the State Water Resources Control Board, were designed to safeguard groundwater, public health and the food supply, while ensuring proper compost pile management and oversight.
“This bill allows for on-site composting of livestock carcasses, an approach that is not only more sustainable but also supported by ranchers, environmental health experts and wildlife advocates alike,” Assemblymember Diane Papan (D-CA-21) told WLJ in a statement. “It’s a commonsense measure that reflects the reality on the ground for rural communities.”
Currently, California prohibits the composting of unprocessed mammalian tissue except under emergency orders. Limited rendering capacity and county-level burial restrictions have left many producers with few options. In some cases, carcasses end up in “bone piles,” which can attract predators such as wolves, bears and mountain lions. AB 411 would give ranchers—especially those without access to rendering facilities—an alternative disposal method.
Kirk Wilbur, vice president of government affairs for the California Cattlemen’s Association (CCA), told WLJ the bill addresses a long-standing problem: insufficient disposal options as rendering facilities close across the state.
“It’s left a lot of our members with really no satisfying way to dispose of their routine livestock mortalities,” Wilbur said.
While AB 411 has broad support from agricultural, environmental and wildlife organizations, the rendering industry remains opposed, citing concerns that it could harm their business. Wilbur believes those concerns are overstated, noting that in other states with composting laws—such as Washington—rendering has remained robust.
“This bill really is for those folks that either aren’t served at all by renderers because of geography or occasionally miss a pickup,” he said.
Wilbur credited years of pilot research by Kasey DeAtley of California State University, Chico, and colleagues, which found on-farm composting to be safe and effective, with moving the idea toward the policy stage.
“There are 42 other states that allow you to compost your livestock on farm,” he added.
Composting study results
A California research project demonstrated that composting livestock mortalities can be an effective and environmentally sound alternative to current carcass disposal methods—and can significantly reduce predator interactions.
Conducted at the Intermountain Research and Extension Center in Tule Lake between 2020 and 2022, the pilot study composted four cattle carcasses using layers of wood chips and straw, maintaining pile temperatures above 131 F for at least 72 hours to destroy pathogens.
As DeAtley told WLJ, the need for the study arose years earlier, following the convergence of two crises. In 2017, extreme heat in Fresno County killed thousands of dairy cows, overwhelming California’s few remaining rendering facilities. Around the same time, gray wolves began reentering northern counties from Oregon, leading to livestock kills in areas where winter conditions made burial nearly impossible.
“We needed another tool in the toolbox,” DeAtley said, noting that many ranchers were left with no option but to drag carcasses into bone piles.
Testing over several years revealed no concerns regarding heavy metals and no detections of fecal coliform or salmonella in more than 60 samples. Nutrient analysis showed the finished compost met healthy soil recommendations, and large carcasses could be mostly decomposed within 90 days.
“We can do this correctly, we can do it responsibly, and we can do it with tools that ranchers already have,” DeAtley said.
Trail cameras revealed a stark difference in wildlife activity: traditional bone piles averaged more than 300 predator visits a year, while the compost pile had only eight. “There were hundreds fewer visits to the compost pile compared to a bone pile,” DeAtley noted, reinforcing earlier observations by Oregon wildlife officials.
Findings from the research directly informed policy discussions on AB 411, with DeAtley saying that composting can be done safely and responsibly, calling it “one small step at a time” toward providing ranchers with a viable, predator-safe disposal option.
Bill progress
The bill has already cleared the Assembly and passed both the Agriculture and Environmental Quality committees in the Senate, and it now awaits review by the Senate Appropriations Committee. That committee is expected to place it in the “suspense file,” where most bills with costs exceeding $50,000 to the general fund are typically placed. The Assembly Appropriations Committee estimated this bill’s cost at $225,000.
Wilbur described the cost as “a really small hit to the state budget and worth absorbing,” noting it could save the California Department of Fish and Wildlife (CDFW) money by reducing predator attractants such as bone piles, which in turn could lower costly wolf-livestock conflict responses—efforts currently costing CDFW about $2 million this summer.
While the Senate Appropriations Committee has not confirmed its suspense file hearing date, Wilbur said it is likely to be Aug. 28 or 29.
“I remain hopeful that AB 411 will move swiftly through the Appropriations Committee and ultimately to the governor’s desk,” Papan said. “California’s cattle producers deserve effective tools to reduce livestock loss and coexist safely with protected species.” — Charles Wallace, WLJ contributing editor
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