An ISU professor is researching whether composting is a better method of disposing of diseased cattle carcasses than burying them.

The Iowa Department of Natural Resources asked Thomas Glanville, associate professor of agricultural and biosystems engineering, to find the impact of composting diseased cattle on the environment.

Usually, in cases of animal death, the carcass is buried. However, because the water table below ground in Iowa is higher than in other areas of the United States, the disease can threaten the water source.

“Cattle composting is an alternative to burial,” Glanville said. “Thus far, the results have been beneficial.”

The decay of cattle carcasses has been extremely rapid and the odor level has been low during composting, he said. Composting creates a lot of heat, which is beneficial in eliminating pathogens. There is also relatively little leachate, or water that seeps down through the pile, which can be harmful if it goes down into the soil and groundwater, Glanville said.

The project is being used to simulate an emergency disease outbreak in cattle, because when a herd of cattle is infected with a dangerous disease, it is controlled by killing the herd. The problem then becomes what to do with the carcasses, said Don Reynolds, associate dean of veterinary medical research.

A vaccine virus similar to harmful foreign diseases is injected into the pile, so there is no risk to humans or animals, Reynolds said. The pile can reach up to 130 or 140 degrees Fahrenheit, which will kill the pathogens, he said.

“The virus is injected into the pile, then checked to see if the pathogens are still alive or if composting killed them,” Reynolds said. “We are checking the piles during very cold temperatures, rainy conditions and hot, dry seasons … for composting.”

The piles are tested to see how long the pathogens last and if they escape the pile. Wind, insects and birds can also help to spread the virus away from the pile to other animals, so chickens were placed in close vicinity to the pile to see if they would acquire the injected vaccine.

“The preliminary findings have been good,” Glanville said. “We are finding that the virus is killed off in two to three weeks.”

Composting has become of interest because previous rendering methods are becoming more costly. On-farm disposal used quickly with minimal special equipment or transportation and readily available materials from around the farm would be very helpful, Glanville said. Corn stalks, silage and yard waste are used to cover the compost pile, he said.

The piles start out at around 10 to 12 feet high. In a couple of months, they are only four or five feet tall due to compaction and the general breaking down of the carcass. The pile does a lot of settling and decomposing, and the mound self-digests a bit, Reynolds said.

When there is no evidence of the live virus in the pile, one of the best ways to destroy any remaining virus is to spread it out in different temperatures and expose it to sunlight, he said.

“The feasibility of the project looks good, but more research needs to be done,” Reynolds said. “Protocols and guidelines still need to be determined, and they will vary from species to species.”