Resource Magazine September/October 2013 : Page 5

As recently as September 2011, the foam caused about a half-dozen explosions in the upper Midwest, where this phe-nomenon is centered. One explosion destroyed a barn on a farm in northern Iowa, killing 1,500 pigs and severely burn-ing the worker involved. Jacobson and Clanton and their team spent much of that first year in the field using a grant from the Minnesota Agricultural Experiment Station Rapid Response Fund, examining both foaming and non-foaming pits, as well as sur-veying farmers throughout southern Minnesota. Their results showed a frustrating lack of connection between the problem sites. At that time, about 25 percent of the farmers they con-tacted had some issue with foaming pits, but nothing appeared to be a common tie among them. Even on a farm with a double-wide barn consisting of two rooms and two pits beside each other, sharing a single wall, it was common to find foaming in one pit and none in the other. “We heard from one producer with three barns that one is foaming and the other two aren’t,” Clanton said. “We tried to identify the differences, but it was the same pigs, the same feed, the same genetics, management, and building. Everything was the same.” “We thought, maybe naively, that we would find some obvious commonality,” Jacobson said. “Maybe we would do some simple lab analysis and something would jump out at us, allowing us to trace it back to a cause. But that didn’t happen.” An explosion on a farm in Iowa leveled the building, above , killing 1,500 hogs and severely burning a farm worker, below . Bo Hu is analyzing the varying effects of DDGS on pig manure and foaming, but the process is difficult, with the wide variety of types and quality of DDGS available to farmers. Photo by Martha Enzler. Burning through theories By the summer of 2010, instances of pit foaming had begun to spread beyond southern Minnesota and northern Iowa, and without a clear connection between cases, the team needed a closer look at the foam. They brought BBE scientist Bo Hu on board to analyze their field samples at a microbial level. On a basic level, three things must be present for a liquid to foam: gas, surfactant, and stabilizer. Methane gas is pres-ent in all manure pits, and the filamentous bacteria might serve as a stabilizer—something that keeps the bubbles from bursting. Hu decided to look at a possible surfactant—soap-like chemicals that initiate bubbles—in this case, long-chain fatty acids. The most likely source of an increase in fatty acids in pig manure is the addition of distiller’s dry grains with solubles (DDGS) into the livestock’s diet, which may cause incom-plete digestion of oils. DDGS is a byproduct of corn process-ing for ethanol that is added to most swine feed. DDGS has shown nutritional value for pigs, but Hu thinks that the high levels of unsaturated fatty acids in DDGS may be part of the foaming equation. Identifying how big an issue this is will be a challenge, since the quality and quantity of DDGS varies widely by refinery, season, and farmer. “From a dietary standpoint, the pig can only metabolize about half of the fatty acids in DDGS, so it all goes back to how much you put into the diet,” said Clanton. “But this is the RESOURCE September/October 2013 5

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