In-Vessel Composting of Poultry Mortality FY98 CWA Section 319(h) Project (project continuing through 2001)

Page last updated on June 12, 2000

This is an implementation/demonstration project funded through the Texas State Soil and Water Conservation Board and managed by the Department of Agricultural Sciences at Texas A&M University-Commerce.  Day-to-day operations are provided by Mr. Wilbur Wilhite, Wilhite Farms, Mt. Vernon, Texas (click here for a map to the project site).

 

Current Texas broiler production approaches 400 million birds annually.  The industry suffers an annual death loss of an estimated 20 million birds in production facilities and produces over 400,000 tons of litter that require disposal.

Natural mortality (dead birds) poses microbial risks to watersheds, and the carcasses create disposal challenges in all production regions due to lack of readily available, environmentally friendly, low management disposal techniques.  The mortality, which may average up to 5% of total production, is currently being disposed of by incineration (photo 1, photo 2), rendering or static bin composting (photo 1, photo 2).  The passage of Senate Bill No. 1910 in Texas in 1997 restricted mass burial as a disposal alternative for carcasses.

Current carcass disposal options can be problematic under some circumstances due either to high costs, extensive carcass handling, labor and management requirements, microbial contamination risks to the watershed, or a combination of these factors.

Mortality is collected daily and loaded into a horizontal, single auger feed mixer equipped with knives to macerate carcasses and mix with the selected bulking agent (sawdust, hay, or cotton gin trash).  The blended compost mass is then loaded (photo 1, photo 2) into an in-vessel composter measuring 6 ft. in diameter and 16 ft. long, and turning at 4 revolutions per hour.  Composting temperatures in excess of 140 degrees F inside the in-vessel composter are sustainable for three days or more.

As product needs to be unloaded from the composter to make room for continued daily additions, the compost is transferred to static bins to mature for a minimum of three weeks prior to use.

Although annual clean-out litter works well as a bulking agent for in-vessel composting of poultry mortality, cake (material removed from production houses between each flock of birds using a housekeeper) does not work well as a bulking agent.  Cake is composed primarily of manure and spilled feed and typically contains little bedding material.  Without bedding material (ex. sawdust or rice hulls), the texture of cake-out material is too fine to provide the required porosity/oxygenation necessary to sustain rapid, thermophilic composting.

The following ratio of compost components (by weight) have been found to work well using in-vessel composting procedures as described above:

25% mortality / 75% sawdust (if sawdust contains 30% moisture)
50% mortality / 50% sawdust (if sawdust contains 15% or less moisture)
75% mortality / 25% cotton gin trash (if gin trash contains 10% or less moisture)
75% mortality / 25% hay (if hay contains 10% or less moisture)

As moisture level of the above bulking agents increase, the quantity of carcasses must be reduced to prevent compost blends from becoming too wet and creating anaerobic conditions.

Composting of poultry mortality from Wilhite Farms'  broiler production houses (photo 1, photo 2) began full-scale in the fall of 1999.  Three compost formulations containing mortality and sawdust, mortality and hay, and mortality and cotton gin trash have been developed for use at the Wilhite Farms demonstration site.

Beef cattle feeding trials utilizing mortality composted with sawdust, "cake-out" litter, and corn were initiated in June, 2000.

Don Cawthon
Department of Agricultural Sciences
Texas A&M University-Commerce
Commerce, TX  75429