The Effect of Microbial Inoculants Applied at Ensiling on Sorghum Silage Characteristics and Aerobic Stability

摘要

Whole crop forage sorghum (Saccharatum) cultivar FS5 was harvested at the soft dough stage of maturity. The sorghum was chopped to approximately 2 cm pieces and ensiled under laboratory conditions in 1.5 L Week glass jars. At ensiling, it was treated with two commercial microbial inoculants; inoculant A and inoculant B. The inoculants were applied at 2 x 10~5 colony forming units g~(-1) DM. Silage with no additives served as a control. Three jars per treatment were opened on days 2, 4, 8, 15 and 60 post-ensiling to study fermentation dynamics. After 60 days of ensiling, the silages were analyzed and subjected to an aerobic stability test lasting 5 days. Results showed that both inoculants caused a more rapid rate of pH decline and a higher amount of lactic acid production. Silages treated with each inoculant produced a little more CO_2 and resulted in more glucose loss as compared with the control. Addition of inoculants did not influence (P > 0.05 ) the ash and crude protein contents, but tended to decrease the concentration of acetic acid (P < 0.05), butyric acid (P<0.01) and propionic acid (P<0.01), and increase the lactic acid concentration (P<0.01). Silages treated with inoculant A possess the more DM loss, and the higher yeast counts upon aerobic exposure. Silage treated with inoculant B had the most DM (P<0.05), lactic acid contents (P<0.01), the least acetic acid content (P<0.05). Inoculant B reduced the ADF (P<0.01), ADL and NDF (P<0.05) contents. It was concluded that lactic bacteria inoculants may improve the fermentation but might impair the aerobic stability for sorghum ensilage.