Microbial Dynamics during Aerobic Exposure of Corn Silage Stored under Oxygen Barrier or Polyethylene Films

Abstract

The aims of this study were to compare the effects of sealing forage corn with a new oxygen barrier film with those obtained by using a conventional polyethylene film. This comparison was made during both ensilage and subsequent exposure of silage to air and included chemical, microbiological, and molecular (DNA and RNA) assessments. The forage was inoculated with a mixture of Lactobacillus buchneri, Lactobacillus plantarum, and Enterococcus faecium and ensiled in polyethylene (PE) and oxygen barrier (OB) plastic bags. The oxygen permeability of the PE and OB films was 1,480 and 70 cm 3 m ؊2 per 24 h at 23°C, respectively. The silages were sampled after 110 days of ensilage and after 2, 5, 7, 9, and 14 days of air exposure and analyzed for fermentation characteristics, conventional microbial enumeration, and bacterial and fungal community fingerprinting via PCR-denaturing gradient gel electrophoresis (DGGE) and reverse transcription (RT)-PCR-DGGE. The yeast counts in the PE and OB silages were 3.12 and 1.17 log 10 CFU g ؊1 , respectively, with corresponding aerobic stabilities of 65 and 152 h. Acetobacter pasteurianus was present at both the DNA and RNA levels in the PE silage samples after 2 days of air exposure, whereas it was found only after 7 days in the OB silages. RT-PCR-DGGE revealed the activity of Aspergillus fumigatus in the PE samples from the day 7 of air exposure, whereas it appeared only after 14 days in the OB silages. It has been shown that the use of an oxygen barrier film can ensure a longer shelf life of silage after aerobic exposure.

Digestibility, fermentation and microbiological characteristics of Calotropis procera silage with different quantities of grape pomace

“…Yeasts may produce high ethanol concentrations in silage (Muck, 2010), which was observed herein because the ethanol concentrations increased with greater yeast populations (Table 4). Dolci et al (2011) studied corn silage with a bacterial inoculant and reported a mold and yeast count of 6 log CFU/g silage, which is similar to the values observed herein without a microbial inoculant.…”

The effects of three silage inoculants on aerobic stability in grass, clover-grass, lucerne and maize silages

“…Yeasts are generally the initiators of aerobic deterioration, consuming sugars and fermentation acids and raising silage temperature (Pahlow et al 2003). Finally, moulds complete the deterioration of the silages (Dolci et al 2011). In the present experiment another indicator showing that yeast activity was suppressed was lower ethanol concentration of the inoculated silages when compared with the corresponding UT silages.…”

The influence of covering methods on the nutritive value of corn silage for lactating dairy cows

“…The authors stated that both systems were successful when operated properly and resulted in negligible surface waste or visible mold. In a recent study, Dolci et al (2011) reported that the low permeability to oxygen of the OB film helped to create a more anaerobic environment, and this was reflected in silages with higher lactic acid concentrations and lower pH and acetic acid concentrations, when compared with PE films. In contrast, O'Kiely and Forristal (2003) did not find differences in the fermentation end-products of grass silages stored in bunker silos covered with either two sheets of black polythene film of 125-μm thickness or a single layer of OB film overlaid with a single protective sheet of black polythene.…”