CONICET | Buscador de Institutos y Recursos Humanos

For an inoculant to be effective, the plant and the selected microorganisms must be compatible. However, variable success rates can be caused by poor silage management, especially when proper moisture concentration is not achieved. This study aimed at investigating the effects of an autochthonous spray-dried microbial inoculant and wilting time on fermentation parameters, microbiological composition, mycotoxin level and aerobic stability of lucerne silages.A 2 × 2 × 4 factorial arrangement of treatments was used, with two different wilting durations (3 or 21 h), with and without bacterial inoculant (Lactobacillus plantarum Hv75, Pediococcus acidilactici 3903 and Lactobacillus buchneri B463) and four fermentation periods (0, 3, 30, 60 days), in a completely randomized design, with three replicates for each treatment and sampling date. The plant material was ensiled in 48 polyethylene containers. Spray-dried bacteria were applied at a theoretical rate of 2 × 106 cfu/g of cropped forage under constant mixing. The same quantity of double distilled water was sprayed uniformly onto the forages without microbial inoculant. Bucket silos were compacted, sealed and stored at room temperature during 60 days. Triplicate micro-silos were opened at each time point of anaerobic fermentation, and subsampled for analysis of fermentation profile, microbiological counts, mycotoxin incidence and aerobic stability. The data were analyzed using the statistical program InfoStat software (Faculty of Agricultural Sciences, National University of Córdoba, Córdoba, Argentina). Lactic acid bacteria (LAB) supplementation increased dry matter and lactic acid content, reduced pH and concentrations of acetic acid, ethanol and ammonia nitrogen/total nitrogen compared to the control (p < 0.05). In addition, inoculation increased total LAB population and decreased yeast and mould counts (p < 0.05). No differences were observed for crude protein, neutral detergent fibre, acid detergent fibre, acid detergent lignin and ether extract between inoculated and uninoculated samples (p > 0.05). Moreover, no significant differences were perceived in the mycotoxin concentrations among treatments (p > 0.05). All samples were contaminated with total aflatoxins (AF) and 94% were contaminated with deoxynivalenol (DON). The average total AF level was 10.7 μg/kg, whereas the mean level of DON contamination was 380 μg/kg. Regarding aerobic stability, all types of silos were stable at least for 4 days, when the experiment was stopped. Therefore, no effect of treatment or pre-ensiling wilting time was identified (p > 0.05). Although the strains displayed potential to be used as a bio-inoculant at different lucerne moisture levels, prolonged wilting positively influenced dry matter, crude protein and fibre degradation (p < 0.05). Therefore, the addition of this spray-dried inoculant to lucerne silages with longer wilting could be recommended for the attainment of silage quality.