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Composting adds value to swine farm losses
MISSISSIPPI STATE -- Part of the challenge in bringing a steady supply of bacon, sausage and ham to the American dinner table is to produce pigs in an environmentally sound manner.
In normal operations, a small percentage of animals die before reaching market weight, and the mortalities must be disposed of in timely and environmentally safe ways. Producers face a significant issue in determining the best method of disposal.
The Board of Animal Health and the Mississippi Department of Environmental Quality work together to develop regulatory policy on this issue. The Mississippi Board of Animal Health oversees disposal by issuing a certificate of compliance once it has approved a facility's method of mortality management.
Mark Crenshaw, swine specialist with Mississippi State University's Extension Service, said producers in Mississippi can dispose of pig carcasses through composting, rendering, incineration or limited burial.
"Composting is a more environmentally friendly way to dispose of mortality than incinerating or placing them in a landfill," Crenshaw said. "Composting conserves nutrients and the end product can improve soil fertility and plant growth.
"Composting swine mortality has been demonstrated to be an effective method of disposal," Crenshaw said. "Composting is a natural, biological process where bacteria and fungi convert organic material into a stable, organic product. Using properly controlled conditions, the composting process can occur rapidly and with little odor generated."
While the Board of Animal Health must issue a permit for all such plans and facilities, the Natural Resources Conservation Service will assist producers with the design of a composting facility and development of an environmentally sound operation plan.
The general procedure to compost hog remains is to place pigs on a base of at least 12 inches of sawdust and cover the carcasses with 2 feet of sawdust. Natural organisms work over time to break down the carcasses. Temperatures in the compost piles can reach as high as 160 degrees, destroying pathogens.
Biosecurity is a primary consideration when selecting a site and constructing a facility. Surface water is diverted from the composting facility to prevent possible contamination of the water supply.
A steady supply of sawdust and at least three bins are needed for the process. Carcasses are placed in the primary bin until it is full and capped off with sawdust, then a second primary bin is started. At least 60 days after placing the last mortality in the primary bin, the contents are moved to a secondary compost bin for at least another 60 days before the contents are finished.
Once cured, the nutrient-rich compost can be applied to farmland.
"The compost should be applied to crop or pasture land at agronomic rates consistent with nutrient levels needed to obtain optimum crop yields," Crenshaw said.
Jim Blissard, a contract grower for Prestage Farms in Chickasaw County, uses composting to eliminate dead pigs. His eight finishing houses have 7,040 hogs that he grows in 18 to 19 weeks from about 45 pounds when they arrive to a market weight of 250 pounds.
When he and his father began operating, Prestage picked up any dead hogs daily. The company stopped this more than a year ago, and Blissard bought an incinerator for hog disposal.
"We discovered pretty quickly that the machine was not going to hold up," Blissard said. "It would get rid of the hogs, but it would be costly to keep up the equipment."
They turned to MSU for assistance in building a hog composting facility made up of a pole shed housing four 20-foot by 10-foot stalls with 5 1/2-foot walls. These bins are built on a cement foundation with cement walls and a roof overhead.
Blissard said he is quite satisfied with the results of composting.
"It's working very well, even better than we expected," Blissard said.
Using the incinerator cost Blissard about $700 to $800 in diesel fuel per round of hogs raised, plus the equipment has to be replaced in time. Once the composting facility was constructed, Blissard said it costs only about $300 per 18-week round to operate. He estimated composting costs his operation about $1,200 a year while the cost to incinerate was more than $2,000 a year.
"I am glad we changed to this method of dead animal disposal because it does seem to be the most economical way of disposing of them," Blissard said.