Rehydration Improves Fermentation Characteristics but Increases Effluent Losses in High Dry Matter Whole-Plant Corn Silage

Harvest delays in corn silage production often result in excessive dry matter (DM) content, impairing fermentation quality and increasing losses. Rehydration has been used in practice as an alternative to mitigate these effects. This study evaluated the effects of rehydration on physical and fermentation characteristics, microbial population, aerobic stability, and losses of high dry matter (DM) corn silages. Five harvests were performed at seven-day intervals, resulting in increasing DM contents (34.7%, 40.7%, 46.9%, 49.5%, and 54.2%). A portion of each high DM harvest was rehydrated to 35% DM before ensiling. Silages were ensiled in 20 L experimental silos for 90 days. Rehydration reduced pH and increased lactic acid concentration and lactic acid bacteria counts. Rehydrated silages showed fermentation characteristics closer to those observed in the control silage (34.7% DM), particularly regarding pH and lactic acid concentration. However, effluent losses increased significantly with rehydration, with the greatest losses observed in silage containing 54.2% DM. Water holding capacity and silage density exhibited variable responses across dry matter levels in non-rehydrated silages. Aerobic stability was improved by rehydration. Rehydration partially restored favorable fermentation conditions in high dry matter corn silage, although greater effluent losses were observed at the highest dry matter content evaluated.