Preservation characteristics of modified wet distillers grains with solubles stored with marginal-quality feedstuffs in laboratory-scale mini silos1

The objective of this experiment was to determine preservation characteristics of modified wet distillers grains with solubles (MWDGS) when stored with corn silage or feedstuffs having a traditionally marginal nutrient profile. Wet distillers grains with solubles (approximately 50% DM) were blended with either corn silage, corn stalks, soybean hulls, or wheat straw at the rate of 75:25, 50:50, or 25:75 (MWDGS:forage; as-fed basis) and stored as silage in laboratoryscale mini silos weighing between 16 and 23 kg. Three replicates of each mixture were opened at 28, 98, and 182 d of storage for assessment of mold. Mini silos opened on d 98 were subsampled and analyzed for chemical composition and aerobic stability. The resulting feed resources were stable at 98 d, having a final pH near or below 4.0, which significantly slows or inhibits yeast, mold, and fungal growth. In general, increasing concentrations of MWDGS in the blend resulted in increased CP (P < 0.001) and decreased ADF and NDF (P < 0.001) at both mixing on d 0 and after 98 d of storage. In 182-d silos, aerobic stability, measured as the time required for the preserved mixtures to increase in temperature by 2°C once exposed to air, improved as more MWDGS were included in corn silage, wheat straw, and soybean hull blends (P ≤ 0.03). The most dramatic improvement was noted in corn silage-based blends, as a 50:50 mixture of MWDGS and corn silage resulted in an increase in stability by a factor of 4 over pure corn silage alone. In summary, copreservation of MWDGS with corn silage or low-quality feedstuffs inherently increased CP and decreased the fiber concentrations within resultant mixtures. Moreover, when MWDGS were combined with corn silage, wheat straw, and soybean hulls, aerobic stability was improved.