INVESTIGADORES
VINDEROLA Celso Gabriel
congresos y reuniones científicas
Título:
Aerobic stability of corn silage inoculated with autochthonous strains of lactic acid bacteria
Autor/es:
BURNS P; BINETTI, A.; BERGAMINI, C.; MAZZONI, R.; VINDEROLA., G.; REINHEIMER J
Reunión:
Simposio; V International Symposium on Lactic Acid Bacteria; 2016
Resumen:
Silage is a fermented high-moisture stored fodder, which is used to feed the cattle. In particular in Argentina, corn is the main crop that is widely used for silage production in a process called ensiling or silaging, where naturally-present or inoculated selected lactic acid bacteria participate in. When silage is exposed to air on opening the silo bag, fermentation acids and other substrates are oxidized by aerobic bacteria, yeasts and moulds, which causes losses and deterioration (ethanol) of the silage and the possible occurrence of micotoxins . The aerobic stability of silage is then a key factor in ensuring that silage provides well-preserved nutrients to the animal. In general, lactic acid-resistant yeasts are the main microorganisms responsible for aerobic instability, raising inner silage temperature and pH due to the fermentation of carbohydrates and lactic acid. In a previous work, 3 lactic acid bacteria strains (L. plantarum Ls71, P. acidilactici Ls72 and L. buchneri Ls141) were isolated and characterized from natural (non-inoculated) corn silage from the Santa Fe region. The aim of this work was to evaluate the performance of the strains in micro-silos (400 g) and in buckets (12 kg) and to assess the aerobic stability of the silage produced in buckets. Chopped corn was inoculated (or not: control) with a mix (1:1:1) of the 3 strains under study to an initial level of 1 x 106 CFU/g) and with cellullosic enzyme (0.05% w/w)]. Silos were incubated at room temperature for 30 days (micro-silos) and 45 days (buckets). pH, counts of yeasts and moulds and total lactic acid bacteria, content of ethanol and lactic and acetic acid (HPLC) and aerobic stability (monitoring of inner temperature of silage after exposure to air) were assessed. After 24 h of fermentation, pH of inoculated silage was significantly lower than control silage (4.00 ± 0.01 and 4.10 ± 0.01, respectively). By day 30 of fermentation (micro-silos), pH was 3.56 ± 0.03 (control) and 3.64 ± 0.01 (inoculated). Counts of yeasts and moulds in inoculated silage (< 1 log order CFU/g) were significantly lower than in control samples (5.82 ± 0.16 log orders CFU/g) whereas counts of total lactic acid bacteria were 6.27 ± 0.13 (control silage) and 8.11 ± 0.23 (inoculated silage). By day 45 of fermentation (buckets), pH was 3.66 ± 0.02 (control) and 3.73 ± 0.02 (inoculated). Counts of yeasts and moulds in inoculated silage (2.36 ± 1.92 log order CFU/g) were significantly lower than in control samples (6.51 ± 0.12 log orders CFU/g) whereas counts of total lactic acid bacteria were 7.11 ± 0.62 (control silage) and 8.49 ± 0.22 (inoculated silage). The inner temperature of inoculated samples remained stable for more than 400 h (aerobic stability assay), whereas the inner temperature of control silage raised 2°C above room temperature after 48 h of exposure to air. The acetic acid content of inoculated silage doubled that of control samples while the lactic acid content was slightly lower in inoculated silage. The level of ethanol was four times higher in control samples that in inoculated silage. The strains used (L. plantarum Ls71, P. acidilactici Ls72 and L. buchneri Ls141) were able to control yeasts and moulds proliferation in silage, to probably remain viable after 45 days of fermentation and to confer aerobic stability to the silage once opened.