Abstract:

[Objective] The aim of this study was to explore the effects of different microbial agents addition and different compaction densities on nutritional components and fermentation quality of corn silage. [Method] Four commercial microbial agents with two compaction densities （750 kg/m³ and 850 kg/m³）, and two microbial agent addition methods （adding the recommended level or the same level） were set up using whole plant silage corn as raw material. The recommended addition levels of the microbial agents A （group A, consisting of 7 bacteria such as Enterococcus faecalis and Lactobacillus paracasei）, B （group B, consisting of Lactobacillus buchneri and Lactobacillus plantarum）, C （group C, consisting of Lactobacillus buchneri, Lactobacillus plantarum and Pediococcus acidilactici） and D （group D, consisting of Lactobacillus plantarum and Lactobacillus buchneri） were 2.5×10¹¹, 1.1×10¹¹, 2.9×10¹¹ and 1.0×10¹² CFU/t, respectively. The same addition level of the four microbial agents was 5.0×10¹¹ CFU/t. Control groups without addition of microbial agents were set at the both compaction densities. After 120 d fermentation, samples of the corn silage were taken to measure and compare the nutritional components and fermentation indicators under different levels of microbial agents addition and at different compaction densities. [Result] At the compaction density of 750 kg/m³, when adding the recommended levels of the four microbial agents, the dry matter content in group D was higher than that in control group, and was significantly （P<0.05） higher than that in groups A and B. When the addition level of the four microbial agents was all 5.0×10¹¹ CFU/t, the dry matter content in group D was significantly （P<0.05） higher than that in control group. Compared with control group, adding the recommended levels and the same level of the four microbial agents all had trend of increase in the contents of crude protein, starch and lactic acid. Adding the recommended levels of the four microbial agents at the both compaction densities, the starch content increased by 5.61% to 9.23% and 2.49% to 6.71%, respectively, and the lactic acid content increased by 11.09% to 25.94% and 15.56% to 38.97%, respectively. At the compaction density of 850 kg/m³, when the addition level of the four microbial agents was 5.0×10¹¹ CFU/t, the dry matter content in groups C and D increased by 2.94% and 2.60% compared to control group, respectively. In comparison with control group, the addition of the recommended levels and the same level of the four microbial agents showed trend of decrease in the content of butyric acid. Overall, different compaction densities had limited effects on the nutritional components and fermentation quality of the corn silage. [Conclusion] Microbial agents addition improves the nutritional components and fermentation quality of corn silage. Higher level addition of the microbial agent consisting of Lactobacillus plantarum and Lactobacillus buchneri has better performance than lower level addition of the microbial agent with the same composition or combinative addition of multiple microorganisms.

Key words: microbial agent, compaction density, whole plant corn silage, nutritional components, fermentation quality