Effects of the addition of peanut vines and corn flour to distiller’s grains on the mixed fermentation quality and rumen degradation rate in vitro

The purpose of this experiment was to study the effects of adding different proportions of peanut vines and corn flour on the anaerobic fermentation quality and rumen degradation rate of distiller’s grains in vitro, namely to improve the nutritional value of distiller’s grains and prolong their safe storage period. Using a two-factor with three levels experimental design, the supplemental levels of peanut vines were 0, 5% and 10% of distiller’s grains (fresh weight basis), respectively. The addition amounts of corn flour were 0, 2% and 4% of distiller’s grains (fresh weight basis), respectively. The fermentation quality and in vitro rumen degradation rate were evaluated after anaerobic fermentation. The results showed that after 180 d anaerobic fermentation, adding peanut seedlings significantly increased the pH of distiller’s grains (P < 0.05), but had no significant effect on the contents of lactic acid (LA) and acetic acid (AA) (P > 0.05). Adding corn flour significantly reduced the AA content of distiller’s grains (P < 0.05), but had no significant effect on pH and LA content (P > 0.05). Adding 5% peanut vines and 4% corn flour at the same time significantly reduced the contents of NH₃-N/TN, propionic acid (PA), and butyric acid (BA) (P < 0.05). The control group had the lowest V-Score, which was 87.83, while the group treated with 5% peanut vines and 4% corn flour had the highest V-Score, which was 97.23. Furthermore, without anaerobic fermentation, adding peanut vines significantly improved the in vitro rumen degradation rate of dry matter (DM) and neutral detergent fiber (NDF) (P < 0.05), while adding corn flour had no significant effect on the in vitro rumen degradation rate of DM and NDF (P > 0.05). Adding 10% peanut vines and 4% corn flour at the same time significantly improved the in vitro rumen degradation rate of crude protein (CP) and acidic detergent fiber (ADF) (P < 0.05). After anaerobic fermentation for 180 d, adding peanut vines and corn flour significantly improved the rumen degradation rate of DM and ADF in vitro (P < 0.05). Adding 10% peanut vine and 4% corn flour at the same time significantly improved the rumen degradation rate of CP and NDF in vitro. In summary, adding peanut vines and corn flour improved the anaerobic fermentation quality of distiller’s grains and increased the rumen degradation rate of fermented distiller’s grains in vitro. Adding 5% peanut vines and 4% corn flour at the same time had the best effect on improving the quality of anaerobic fermentation, while adding 10% peanut vines and 4% corn flour at the same time had the best effect on improving the rumen degradation rate of fermented distiller’s grains in vitro.