Anaerobic lactic acid degradation during ensilage of whole crop maize inoculated with Lactobacillus buchneri inhibits yeast growth and improves aerobic stability

Aerobic deterioration of silages is initiated by (facultative) aerobic micr o-organisms, usually yeasts, that oxidize the preserving organic acids. In this study, a Lactobacillus buchneri strain isolated from maize silage was evaluated for its potential as a bacterial inoculant that enhances aerobic stability of silages. In four experiments, chopped whole crop maize (30-43% dry matter (DM)) was inoculated with Lact. buchneri and ensiled in laborat ory silos. Uninoculated silages served as controls. Analysis of silages tre ated with Lact. buchneri at levels of 10(3)-10(6) cfu g(-1) after about 3 m onths of anaerobic storage showed that acetic acid and 1-propanol contents increased with inoculum levels above 10(4) cfu g(-1),whereas lactic acid de creased. Propionic acid, silage pH and DM loss increased with inoculum leve ls above 10(5) cfu g(-1.) Time course experiments with maize inoculated wit h Lact. buchneri at 4 x 10(4)-2 x 10(5) cfu g(-1) showed that up to 7-14 d after ensiling, Lact. buchneri had no effect on silage characteristics. The reafter, the lactic acid content of the inoculated silages declined and, si multaneously, acetic acid and, to a lesser extent, propionic acid and 1-pro panol, accumulated. Inoculation reduced survival of yeasts during the anaer obic storage phase and inhibited yeast growth when the silage was exposed t o O-2, resulting in a substantial improvement in aerobic stability. The res ults indicate that the use of Lact. buchneri as a silage inoculant can enha nce aerobic stability by inhibition of yeasts. The ability of the organism to ferment lactic acid to acetic acid appears to be an important underlying principle of this effect.