Association of Lactobacillus buchneri with aerobic stability of total mixed ration containing wet brewers grains preserved as a silage

Abstract: Laboratory-scale plastic silos were prepared to examine bacterial factors associated with the aerobic stability of total mixed rations (TMR) preserved as a silage after mixing. In experiment 1, TMR silages containing wet brewers grains (BG), hay (lucerne or sudangrass), maize grain, wheat bran, beet pulp and liquid molasses, were ensiled for 14 and 56 days, and bacterial communities were examined by denaturing gradient gel electrophoresis (DGGE). The silages resisted aerobic deterioration for as long as 2 weeks, except that heating occurred after 5.5 days in 14-day silage prepared with sudangrass hay. The DGGE analyses indicated that, although not found in the materials, Lactobacillus buchneri and L. brevis were detectable in long-stored TMR silage. L. delbrueckii and L. fermentum were found in the materials, and appeared to survive during fermentation and after exposure to air. There were few changes in the DGGE profiles before and after heating in deteriorated silage containing sudangrass hay. In experiment 2, TMR silage with ingredients similar to those in experiment 1 was prepared, and culturable lactic acid bacteria were isolated from the plates of de Man-Rogosa-Sharpe agar. L. delbrueckii and L. fermentum were obtained from the materials but not from TMR silage. L. buchneri and L. brevis were not found in the materials, but more than one-third of the isolates were L. buchneri and L. brevis in 14- and 56-day silages, respectively. In experiment 3, whole crop maize was inoculated with L. buchneri, L. brevis, L. delbrueckii and L. fermentum isolates, and fermentation and aerobic stability were determined. No changes occurred from L. brevis, L. delbrueckii and L. fermentum inoculation, while aerobic spoilage was suppressed by L. buchneri with increases in pH and acetic acid content. Results indicate that, whilst not found in BG or the TMR mixture, L. buchneri can become detectable during fermentation, and this bacterium helps establish aerobic stability of BG-containing TMR silage. [Copyright &y& Elsevier]