The following is from the Swine Management News Column of Kenneth B. Kephart, Extension Swine Specialist for the Department of Dairy and Animal Science, Penn State University (Feb., 1992)
Animal rights, manure odors, and lousy market prices have given pork producers their share of aggravation. Now I'm about to suggest that another issue is waiting to erupt for every livestock producer--dead animals. We generate a lot of them, and I suspect that sooner or later someone is going to figure that out. The first question will be, "What does the industry do with all of those carcasses?" Our answer, if we're honest, may not give us high marks.
We can assume that from each litter of pigs, one will be born dead and another will die before weaning. Before market, another half a pig will die. A rough estimate of these death losses would be about 40 lbs. per litter.
Sows will average about two litters per year, which makes the annual death losses about 80 lbs. per sow. Multiply that times the 100,000 sows in Pennsylvania alone (as of Dec, 1991), and we have a staggering pile of dead hogs.
According to Pennsylvania Act 317, passed in 1945, we have three options: burn, bury or render. Producers "...owning any animal that has died shall not allow the carcass to lie about his premises."
This act provides no details on burning, however the Department of Environmental Resources does have recommended criteria for emissions from "crematory incinerators."
If a producer chooses the burial route, the site must not be subject to overflow from ponds or streams, and must be at least "...100 feet from any water source, public highway, house or stable." In addition, the carcass must be covered with at least three inches of lime and two feet of soil.
Renderers must be licensed, and there are requirements listed for how the renderer must operate.
From an informal assessment, I've found that most of the large operations choose rendering as their method of dead pig disposal. Biosecurity is a potential risk when sending dead animals to the renderer. You should assume that the rendering truck is loaded with any organism that's ever been invented. Use the same precautions at the time of dead animal pickup or drop off that you would in an auction barn.
[After some discussion of various name brand incinerators, the author notes:] If the largest unit (600 pound capacity, 2.75 gal fuel/hr.) were used for 14 hours per week, it could easily handle a 300 sow farrow to finish operation. At $1.00/gal, the annual fuel cost would be about $2000. Add to this a depreciation value of $400, and the total cost of dead pig disposal amounts to $2400, which doesn't compare too favorably with the current costs of rendering.
Burial requires a little more work, but it's generally the most practical system for operations off the beaten path, and it's cheap. The biggest concern I have with burial is the way it's done. Many producers dig a trench, fill the trench with dead pigs, and cover as they go. If they cover with lime (most people don't) and two feet of soil, this method is technically legal. But in time, enough rotting flesh could accumulate that ground water could easily be contaminated, especially in areas of limestone, sink holes, shale or sand.
Manure spreaders are not legal, and not in the best interest of biosecurity.
Some operations have established symbiotic relationships with local scavenger populations such as buzzards and alligators. Dead hogs are hauled up to the hill-side and the buzzards do their thing, sometimes, I am told, within a matter of hours--a routine not listed in the 1945 law. Alligators are popular in Florida. Ernie Nunez maintains over 7000 gators to clean up the dead from his 2000 sows and 200 cows.
Composting is working for the poultry industry, and I think it has promise for the hog industry. Dead animals, straw and manure are mixed together and Mother Nature does the rest. If the pile is kept aerobic (at least 30% free air space), at the right moisture level (40-60%), and the correct pH (5-12), the organic material will decompose under temperatures of about 150 degrees F. That's enough to kill harmful microorganisms.
Dr. T. Veum and others at the University of Missouri recently demonstrated that composting works for dead hogs. They utilized empty pens (approx. 6.5 ft X 9.5 ft) in an open front hog building. To each pen they added a layer of straw (about 5 lbs./sq. ft), then a layer of dead pigs, followed by a dry manure/straw mixture, and another layer of straw equal to one half of the weight of dead pigs. The layers were repeated until a final depth of about 3 feet was reached.How veal is made