Determination of aerobic deterioration of corn stalk silage caused by aerobic bacteria

Aerobic deterioration of silage is an important problem in silage production because it affects not only the silage quality but also the animal health. The objective of the current study was to investigate the aerobic stability of corn stalk silage and the role of microbes resulting in aerobic deterioration. Corn stalks were ensiled in evacuated plastic bags for 65 days at room temperature. After the bags were opened, the silages were subjected to treatment with chloramphenicol (CL) or without CL (WCL). The aerobic bacteria and yeast compositions of silages at opening and after exposure to air for 7 days were investigated by analyzing the sequence divergence in the 16S ribosomal DNA gene and in the D1/D2 region of the 26S ribosomal DNA gene, respectively. The results showed that corn stalk silages were well preserved, indicated by the low pH value and high lactic acid content. At the opening of bags, the aerobic bacteria in corn stalk silage consisted of Myroides odoratimimus, Acinetobacter soli, Stenotrophomonas maltophilia, Serratia nematodiphila, Bacillus pumilus and Lysinibacillus fusiformis, but contained undetectable amounts of yeasts (<2.00 10 log cfu/g FM). After exposure to air for 7 days, WCL silage deteriorated, while CL silage did not, because aerobic bacteria were inhibited by CL. Further study showed that L. fusiformis were predominant in WCL silage (0.625 of aerobic bacteria) and metabolized lactic acid. Therefore, in the present study, L. fusiformis resulted in aerobic deterioration of corn stalk silage.