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Continued Progress with Composting for Disposing of Dead Swine
Livestock Update, November 2001
Allen Harper, Extension Animal Scientist-Swine, and Mark Estienne, Swine Research Physiologist, VA Tech Tidewater AREC
Traditional methods of dead animal disposal on Virginia swine farms include burial, rendering and incineration. Each method is considered legal when performed correctly. However, these methods have inherent disadvantages and effective dead hog disposal continues to be a challenge on many farms.
Composting is an accepted method for dead bird disposal on Virginia poultry farms and is used effectively for swine disposal in many other states. Last year, we initiated program activities to increase technical information available for Virginia producers to make use of composting for mortality disposal. The first project included construction and evaluation of a "mini-composter" to demonstrate composting of piglets and afterbirth tissues from farrowing operations. The unit consisted of four, 40 by 36 inch panels constructed of pressure treated lumber and hardware cloth. In the initial demonstration with the mini-composter, 405 lb of pigs and afterbirth tissue from 3 farrowing groups was effectively composted with hardwood sawdust in 171 d.
Subsequently, a grant from the Virginia Agriculture Council was obtained to construct a facility to demonstrate composting of larger hogs. The larger unit is a pole-type structure with 8 composting bins that are 5.5 by 8 by 5 feet in size. In the initial demonstration with this unit, 4 sow carcasses ranging from 365 to 410 lbs were placed each in separate bins with hardwood sawdust bulking agent. Twenty gallons of water was added to the sawdust medium around each carcass. On day 28 after placement, 2 bin piles were opened to assess tissue breakdown. A 408 lb carcass had been reduced 71% to 117 lbs. and a 410 lb carcass had been reduced 74% to 105 lbs. Ten gallons of water was added to each of these bins and the tissues were covered again. After a 58 d primary composting period, all four bins were opened and tissue reduction was determined. The bins that had been opened and re-covered on day 29 had total tissue reductions of 86 to 88% on day 58. Those that were left undisturbed for the 58-day period had tissue reductions of 75 to 77%. Overall, a total of 1551 lbs. of sow tissue was reduced to 284 lbs for an 82% reduction (see table) and then "turned" into a single bin with a front-end loader for a secondary composting period. Eighty gallons of water was added to the sawdust medium and tissue when the material was turned into the secondary bin.
Composting Sow Carcasses - Primary Composting Period
| Bin number | Placement 7-2-01 | Assessment 7-31-01 (day 29) | Replacement 7-31-01 (+ water) | Recovery 8-29-01 (day 58) | Percent Reduction (day 58) |
|---|---|---|---|---|---|
| 1 | 365 lb sow | Not opened | Not opened | 91 lb | 75% |
| 3 | 368 lb sow | Not opened | Not opened | 85 lb | 77% |
| 2 | 408 lb sow | 117 lb | 117 lb | 57 lb | 86% |
| 4 | 410 lb sow | 105 lb | 105 lb | 51 lb | 88% |
| Totals: | 1551 lb | 284 lb |
During the primary composting period, temperatures reached 130 degrees F seven days after placement and remained above this temperature for 18 days. In the secondary composting phase, temperatures increased from 92 degrees F to 130 degrees F within two days and remained between 130 and 150 degrees F for 23 days. Temperatures remained between 120 and 130 degrees F for a subsequent 22-day period. It is apparent that turning the compost pile to introduce oxygen and adding water to create appropriate moisture conditions restarts the composting process and enhances breakdown of the carcass tissues.
A second demonstration was initiated in September with 1878 lb of carcasses (2 sows and 6 market pigs) placed in 2 primary bins over a 2-week period. This test and other demonstrations will be presented at a producer workshop scheduled for Tuesday, November 13 from 10:30 am to 2:30 pm at the VA Tech Tidewater AREC swine unit in Suffolk. All swine producers and related industry people are encouraged to attend. Lunch will be provided and there is no cost for the workshop. Participants are requested to pre-register by contacting Debbie Britt at 757-657-6450, ext. 102 or sending an email to Allen Harper at alharper@vt.edu.
If properly managed, it appears that composting is a viable option for disposal of small and large swine carcasses that normally occur on hog farms. Remaining obstacles to adoption of swine composting on a larger scale in Virginia include approval of the practice by the State Veterinarian and qualification of the practice for state cost-share programs. These approvals have existed since 1992 for Virginia poultry growers and efforts are ongoing to achieve the same for swine producers.