Abstract: [Objective] To investigate the effects of adding Pediococcus acidilactici （P. acidilactici） and Lactobacillus brevis （L. brevis） on fermentative quality and aerobic stability of corn and ryegrass silage. [Method] Experimental strains of P. acidilactici and L. brevis were isolated from fermented TMR. Thirty-day-long silage fermentation trials using whole plant corn and ryegrass were conducted by setting four treatment groups, including control group （adding tap water）, PA group （adding P. acidilactici）, LB group （adding L. brevis） and PA + LB group （simultaneously adding P. acidilactici and L. brevis）. After the sealed silage was opened, the indicators associated with silage quality, such as pH value, lactic acid content, acetic acid content, and the number of lactic acid bacteria and yeasts were determined, and the aerobic stability test was carried out. [Result] For corn silage, after a 30-day-long fermentation, no significant （P>0.05） differences in pH value and lactic acid content among the four treatment groups were observed; the contents of acetic acid in LB group and PA + LB group were significantly （P<0.05） higher than that in control group, and the numbers of lactic acid bacteria in PA group and PA + LB group were significantly（P<0.05） higher than that in control group; in the aerobic stability test, the spoilage of corn silage in PA + LB group was observed after 5 days of opening, and those in the other groups were observed within 2.5 days after opening. For ryegrass silage, after a 30-day-long fermentation, the pH values and ethanol contents in the experimental groups added with lactic acid bacteria were significantly （P<0.05） lower than those in control group, and the lactic acid content was significantly （P<0.05） higher than that in control group with the highest value in PA group; in the aerobic stability test, except for control group, the spoilage of ryegrass silage in the experimental groups added with lactic acid bacteria was observed after 7 days of opening, the lactic acid content in PA + LB group was the highest, and the acetic acid content in PA + LB group was significantly （P<0.05） lower than that in LB group. [Conclusion] Single addition of P. acidilactici or L. brevis has no significant effect on quality and aerobic stability of corn silage, and the combinative addition of P. acidilactici and L. brevis has no significant improvement in fermentative quality of corn silage, but improved its aerobic stability. Addition of lactic acid bacteria improves the fermentative quality and aerobic stability of ryegrass silage, and addition of P. acidilactici has the best performance in improving the fermentative quality. Furthermore, the combinative addition of P. acidilactici and L. brevis not only improves aerobic stability of ryegrass silage, but also improve its fermentative quality.

Key words: lactic acid bacteria additive, silage, fermentative quality, aerobic stability