Evaluation of the Quality and Nutritional Value of Modified Corn Wet Distillers’ Grains Plus Solubles (mcWDGS) Preserved in Aerobic and Anaerobic Conditions

To enhance the effectiveness of sustainable preservation of modified corn wet distillers’ grains plus solubles (mcWDGS), various additives were tested under aerobic and anaerobic conditions. In Experiment I, the mcWDGS was stored under aerobic conditions for 5 days at 25 °C. Treatments included different organic acids applied at 0.3% or 0.6% of fresh matter (FM). In Experiment II, the mcWDGS was ensiled anaerobically for 8 weeks at 25 °C using organic acids, a commercial acid mixture, or a microbial inoculant at 0.2% FM. In aerobic conditions, the best preservability was achieved with propionic and formic acids at 0.6% FM, as indicated by the lowest temperature, pH, and microbial counts on days 3 and 5 ( p ≤ 0.01). Under anaerobic storage, the highest lactic acid concentrations were recorded in the control, citric acid, and commercial acid mixture variants ( p ≤ 0.01). Acetic acid levels were highest in the control ( p ≤ 0.01). The highest NH3-N content was found in the formic acid variant and the lowest in the inoculant variant ( p ≤ 0.01). Aerobic stability after ensiling was greatest in the control and propionic acid groups ( p ≤ 0.01). Nutritional analysis showed that the citric acid group had the highest dry matter content ( p ≤ 0.01), while the control group contained the most crude protein ( p ≤ 0.01) and saturated fatty acids ( p ≤ 0.05). The propionic acid and commercial acid mixture variants had the highest unsaturated fatty acids ( p ≤ 0.05). Antioxidant capacity was also greatest in the control ( p ≤ 0.01). In conclusion, mcWDGS can be effectively preserved aerobically with 0.6% FM of propionic or formic acid, and anaerobically via ensiling, even without additives. These findings support its potential as a stable and nutritious feed ingredient.