Effect of microbial inoculation and storage length on the fermentation profile and nutritive value of high-moisture corn ensiled at 2 different dry matter concentrations

The objective of this experiment was to evaluate the effect of microbial inoculation and storage length on the fermentation profile and nutrient composition of high-moisture corn (HMC) ensiled at 2 different dry matter (DM) concentrations. High-moisture corn was harvested when kernel DM concentrations were approaching 65% as-fed, and either left undried (HMC65; 67.6% DM) or dried at 40 degrees C to approximately 70% DM (HMC70; 71.0% DM), and then ensiled in quadruplicate vacuum pouches untreated (CON) or after one of the following inoculant treatments: 6.36 x 10(5) cfu of Lentilactobacillus buchneri DSM 12856, Lactiplantibacillus plantarum DSM 12836, and Pediococcus acidilactici DSM 16243 per g of HMC (LBLP); or 3.0 x 10(5) cfu of Lentilactobacillus buchneri DSM 12856, Lentilactobacillus diolivorans DSM 32074, and P. acidilactici DSM 16243 per g of HMC (LBLD). Vacuum pouches were allowed to ferment for 7, 14, 28, or 56 d. A three-way interaction was observed (P = 0.01) for the pH of HMC, where CON for HMC70 was greatest across storage lengths and HMC65 treatments generally had a lower pH than other treatments. Concentrations of total acids were greater (P = 0.001) in HMC65 than HMC70 and greater (P = 0.001) in HMC treated with LBLP and LBLD than CON. An interaction between DM concentration, microbial inoculation, and storage length was observed (P = 0.05) for concentrations of acetic acid. At 14 d, acetic acid concentrations were greater in HMC65 treated with LBLD than other treatments. Likewise, at 56 d, concentrations of acetic acid were greatest in HMC65 treated with LBLD, followed by HMC70 treated with LBLD. An interaction between DM concentration, microbial inoculation, and storage length was observed (P = 0.05) for 7-h starch disappearance (starchD). Across all DM concentration and inoculant treatment combinations, starchD increased with increasing storage length. StarchD was also generally greater for HMC65 treatments compared to HMC70, with small differences among inoculants. Results suggest that microbial inoculation can improve fermentation of HMC by increasing the production of antifungal acetic acid, but that DM concentration at ensiling remains a primary determinant of HMC fermentability. Lay Summary High-moisture corn (HMC) short-term fermentation is affected by dry matter (DM) concentration. Thus, producers try to influence HMC fermentation by using microbial inoculants and by harvesting HMC at different DM concentrations. This study aimed to evaluate the effects of different DM concentrations, heterofermentative microbial inoculants, and storage length on the fermentation and nutritive value of HMC. Total acid production was greater in HMC with a lower DM and treated with microbial inoculants. Lactic acid concentrations were generally greater in lower DM HMC. Microbial inoculants increased the production of acetic acid, an antifungal acid. Because acetic acid can improve aerobic stability, these results demonstrate microbial inoculation and lower DM can improve HMC fermentation. However, DM concentration seems to influence fermentation to a greater extent than the use of microbial inoculants. Although starch concentration was not affected by microbial inoculants or DM concentration, starch digestibility was greater in lower DM HMC. This demonstrates lower DM may improve nutritive value in addition to improving fermentation by increasing the production of total acids and lactic acid in HMC. Moisture concentration drives high-moisture corn fermentation by decreasing pH and increasing the production of organic acids, suggesting greater microbial activity increased proteolysis and starch availability in this experiment at lower DM.