Influence of hybrid, moisture, and length of storage on the fermentation profile and starch digestibility of corn grain silages

The ensiling process, as well as the hybrid type and moisture content of corn grains, can affect the fermentation profile and nutrient digestibility of grain silages. Therefore, this study evaluated the effects of hybrid type, grain moisture content at harvest, and length of storage on the fermentation profile, DM digestibility (DMD), and starch digestibility (StarchD) of corn grain silages. We evaluated corn grains harvested at three moisture contents: at approximately 500 g/kg DM (500DM); high-moisture corn at approximately 700 g/kg DM (HMC); and dry grain at approximately 800 g/kg DM, reconstituted to approximately 700 g/kg DM (RC). At RC and HMC, the flint hybrid had an average of 24 % higher (P < 0.05) zein content than that of the soft hybrid prior to ensiling, but after 7 d of ensiling, there were no differences in zein content between hybrids. The StarchD at 12 h and 24 h was negatively correlated with the zein content (P < 0.01, R² = - 0.84 and R² = - 0.87, respectively) and positively correlated with the concentrations of ammonia-nitrogen (P < 0.01, R² = 0.81 and R² = 0.77, respectively) and SP (P < 0.01, R² = 0.88 and R² = 0.80, respectively). After 60 d of ensiling, the DMD and StarchD at 24 h were similar for all silages, independent of the hybrid type or moisture content. After 7 d of ensiling, the RC silages had a higher (P < 0.05) pH (4.90 vs. 4.24), ethanol content (9.29 vs. 5.29 g/kg DM), and 2,3-butanediol content (8656.71 vs. 782.76 mg/kg DM) than those of the HMC silages. After 21 d of ensiling, the RC silages had a higher (P < 0.05) DM losses (58.3 vs. 21.4 g/kg) and acetone content (78.11 vs. 4.60 mg/kg DM) than those of the HMC silages. After 60 d of ensiling, the RC silages had a higher (P < 0.05) butyric acid content (1355.48 vs. 7.98 mg/kg DM) than that of the HMC silages. In conclusion, ensiling HMC and RC for 60 d reduced the negative effects of high vitreousness on the DMD and StarchD due to the proteolysis of the prolamin matrix.