Effects of Lactiplantibacillus plantarum inoculation on the quality and bacterial community of whole-crop corn silage at different harvest stages

Background: Silage is achieved by anaerobic fermentation of lactic acid bacteria. However, harvest stage and Lactiplantibacillus plantarum (L. plantarum) content affect the changes of microbial community in silage, which play an important role in silage quality and mycotoxin levels. The current study evaluated the effects exerted by the application of L. plantarum on fermentation, mycotoxins and bacterial community of whole-crop corn silage at different harvest stages. The fresh whole plant corn from the same area was harvested during the milk stage and the dough stage, following which from each harvest stage was subjected to four L. plantarum treatments: 0 cfu/g; 1 x 10(6) cfu/g; 1 x 10(7) cfu/g; and 1 x 10(8) cfu/g in a 2 x 4 factorial experimental design. Samples were collected on days 0, 3, 7, 21 and 42. Subsequently, nutrition parameters, fermentation parameters, mycotoxin levels and bacterial community were determined. Results: Prolonging the harvest stage resulted in an increase in the levels of starch and dry matter as well as deoxynivalenol in corn silage. Addition of 1 x 10(7) cfu/g and 1 x 10(8) cfu/g of L. plantarum applied after 42 d of ensilage reduced dry matter loss, which significantly lowered deoxynivalenol concentration in corn silage at the dough stage (P< 0.01). The pH of corn silage decreased, whereas the lactic acid concentration increased after ensiling. The effects exerted by the interaction (harvest stage x dose of L. plantarum) on pH on day 21 as well as on fermentation and lactic acid on days 21 and 42 were significant (P< 0.05). Addition of 1 x 10(7) cfu/g of L. plantarum at the dough stage significantly increased the relative abundance of Firmicutes while decreasing that of Bacteroidetes, compared to when L. plantarum was not added (P < 0.05). Conclusions: Adding L. plantarum improved the fermentation quality and bacterial community of silage, which reduced part of mycotoxin content and relative abundance of harmful bacteria. In addition, adding L. plantarum in dough stage resulted in greater improvements to mycotoxin content and bacterial community.