Measuring manure depth in the PEDv era
August 20, 2014 by Jerry May Michigan State University Extension
August 20, 2014, East Lansing, MI – The Porcine Endemic Diarrhea virus (PEDv) continues to impact the U.S. pork industry. Farms that have avoided the virus continue to implement intensive precautions to keep PEDv out of their herd. Farms that have already experienced the ravages of the virus are taking steps to prevent reinfection.
PEDv is spread through oral fecal contact and requires exposure to only a small amount of fecal material to cause infection. Adding to the complications of preventing PEDv reinfections is the virus’s ability to stay viable in stored manure. Research conducted by Goyal at the University of Minnesota and reported by the National Pork Board has confirmed PED virus may stay viable in manure stored at 40F (4C) greater than 28 days. Therefore, stored manure with viable virus, if brought to the floor surface, could re-infect susceptible pigs with PEDv.
In Michigan, large livestock farms (CAFOs), who are covered under the MI Department of Environmental Quality (M-DEQ) National Pollution Discharge Elimination System (NPDES) permit, are required to monitor and weekly record manure depth in each of the farm’s manure storage structures. In addition all livestock farms, regardless of size, should record the amount of manure removed when spreading manure. Prior to PEDv, using a stick to measure manure depth in deep-pitted barns, was of small risk to infect pigs with a virus or bacteria. Currently, in this era of PEDv, there is a risk the small amount of manure brought up on the measuring stick may re-infect the pigs.
One option to avoid recontamination in a barn previously infected with PEDv, is to stick and measure manure depth outside of the barn using the manure pump-out ports. However, there remains the risk of contaminating the periphery of the site and vectors such as personnel or rodents tracking manure virus particles back into the barn and exposing the pigs.
As any 8-year-old boy will attest, a better alternative to the stick is a laser. By aiming the laser’s beam down through the slat opening, a laser measure will determine the freeboard between the manure surface and the top of the slats. Dependable laser measures can be purchased for $80 to $125 either online or at local hardware stores. A quick field trial using the laser method demonstrated it was easier than the stick and accurate despite the presence of dust and cobwebs.
A laser measure is an excellent device for all sizes of swine farms to use when calculating the manure application rate needed as part of the record keeping requirements when hauling manure. Simply measure the depth of the manure before starting to haul then measure again when done. Once the depth of manure removed is known it is easy to determine the number of gallons removed and the manure application rate per acre. To calculate gallons per acre convert all dimension to feet (pit length, pit width and depth of manure removed) then multiply length x width x depth which equals cubic feet of manure removed; cubic feet of manure removed x gallons per cubic foot (7.48) = total gallons removed; total gallons remove ÷ number of acres spread = gallons per acre.
Many farms that have experienced PEDv outbreaks are continuously implementing intensified biosecurity measures to help protect their herd from infection. Until more is understood concerning the virus’s extended viability, Michigan State University Extension advises using precaution and assuming the viable virus remains in the manure. On these sites, it is best to avoid exposing pigs to stored manure as a step to prevent reinfection. In the PEDv era, the stick and measure method may be obsolete.