SDSU research: Wet distillers grains with silage

SDSU research: Wet distillers grains with silage
Recent research at South Dakota State University explored whether producers can preserve wet distillers grains better by combining them with corn silage.

SDSU Extension Dairy Specialist Alvaro Garcia said SDSU scientists will be on hand at Dakotafest to discuss that topic, as well as issues such as dealing with nitrates in drought-stressed corn, with interested producers. Dakotafest 2006 takes place Aug. 15-17 at the southeast outskirts of Mitchell.

Garcia explained that aerobic deterioration, particularly during warm weather, can make it difficult to preserve wet distillers grains. This is due to the fact that oxygen enhances yeast growth during storage, which is responsible for heating.

Research has shown that inoculating silages with acetic acid reduces yeast survival and enhances preservation. Research trials at the University of Wisconsin in 2001 suggest that inoculating silage with a bacterium (Lactobacillus buchneri) produced acetic acid during fermentation, inhibited yeast growth, improved air stability of silages and the total mixed rations that contain them, and resulted in improved milk production.

However, SDSU research got encouraging results by combining wet distillers grains and corn silage, even without inoculation, Garcia said.

Researchers at SDSU's Dairy Science Department tested corn silage-wet distillers grains combinations at 75:25 and 50:50 ratios. The crude protein content was 15.6 and 20.7 percent for the 75 and 50 percent corn silage blends, respectively. In spite of the high pH of the green chopped corn (5.7) the initial pH of both blends was 4.6 and 4.0 for the 75 and 50 percent corn silage respectively. This was attributed to the low initial pH (3.1) of the wet distillers grain when it came from the ethanol plant. By day 14 in the silo-bag, acetic acid concentration in both blends exceeded 3 percent of the dry matter.

By day 129 the acetic acid concentration on the 75 percent corn silage blend reached 5.7 percent, a value similar to that observed by University of Wisconsin researchers in bacterium-inoculated, high acetic acid silages.

Although further research is needed, Garcia said the low pH and high acetic acid concentration suggests preservation can be enhanced by the combination of both feedstuffs.

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