Summary Advances in micro‐organism identification techniques have resulted in increased knowledge of the diversity of prokaryotes and eukaryotes in silage. Such knowledge has enhanced the understanding of how fermentation occurs in forage crops with different characteristics and how the process can be improved to enhance silage quality. Undesirable micro‐organisms can grow in silage when fermentation does not occur properly. Such micro‐organisms may be pathogenic and/or produce toxic metabolic compounds; however, information on the consequences of these metabolites on the health of animals that consume silage is still lacking. The major challenge of ensilage is to produce high‐quality feed that is nutritional, sanitary and stable, with a high dry matter recovery rate, in a process involving no interventions during fermentation and considerable variation in the characteristics of the substrates. It is important to note that each substrate has particularities and that we can only improve fermentation if we fully understand microbial diversity. This review is intended to update information related to the fermentation profile of silage, focusing on microbial diversity.

Sugar cane (Saccharum spp.) is a forage crop widely used in animal feed because of its high dry matter (DM) production (25 to 40 t/ha) and high energy concentration. The ensiling of sugar cane often incurs problems with the growth of yeasts, which leads to high losses of DM throughout the fermentative process. The selection of specific inoculants for sugar cane silage can improve the quality of the silage. The present study aimed to select strains of lactic acid bacteria (LAB) isolated from sugar cane silage and to assess their effects when used as additives on the same type of silage. The LAB strains were inoculated into sugar cane broth to evaluate their production of metabolites. The selected strains produced higher concentrations of acetic and propionic acids and resulted in better silage characteristics, such as low yeast population, lower ethanol content, and lesser DM loss. These data confirmed that facultative heterofermentative strains are not good candidates for sugar cane silage inoculation and may even worsen the quality of the silage fermentation by increasing DM losses throughout the process. Lactobacillus hilgardii strains UFLA SIL51 and UFLA SIL52 resulted in silage with the best characteristics in relation to DM loss, low ethanol content, higher LAB population, and low butyric acid content. Strains UFLA SIL51 and SIL52 are recommended as starter cultures for sugar cane silage.

The selection of microbial inoculants for each crop promotes improvement of silage quality. Studies on the chemical and microbiological characteristics of silage provide useful information for improving ensiling techniques.

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Aims The aim of this study was to evaluate the chemical and microbiological characteristics and to identify the lactic acid bacteria (LAB) and yeasts involved in rehydrated corn kernel silage. Methods and Results Four replicates for each fermentation time: 5, 15, 30, 60, 90, 150, 210 and 280 days were prepared. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and PCR‐based identification were utilized to identify LAB and yeasts. Eighteen bacteria and four yeast species were identified. The bacteria population reached maximum growth after 15 days and moulds were detected up to this time. The highest dry matter (DM) loss was 7·6% after 280 days. The low concentration of water‐soluble carbohydrates (20 g kg−1 of DM) was not limiting for fermentation, although the reduction in pH and acid production occurred slowly. Storage of the rehydrated corn kernel silage increased digestibility up to day 280. Conclusions This silage was dominated by LAB but showed a slow decrease in pH values. This technique of corn storage on farms increased the DM digestibility. Significance and Impact of the Study This study was the first to evaluate the rehydrated corn kernel silage fermentation dynamics and our findings are relevant to optimization of this silage fermentation.

The objective of this work was to evaluate the effects of a new strain of Lactobacillus buchneri (UFLA SIL 72) isolated from sugar cane (Saccharum spp.) silage and the addition of propionic acid [1% based on fresh matter (FM)] to silages treated with and without calcium oxide (1% of FM) at 60 and 170 d of ensiling. A randomized block design with a 2 · 2 · 2 · 2 factorial arrangement of treatments was used to analyse the results. The use of calcium oxide reduced the ethanol content and neutral detergent fibre in all silages, increased pH values and favoured the growth of clostridia and yeasts. The addition of propionic acid reduced the yeast population, but it was not able to reduce ethanol content of silage. The addition of L. buchneri resulted in silages with higher concentration of propionate, reduced the levels of ethanol and reduced the population of clostridia in all silages. The use of calcium oxide is not recommended for silage of sugar cane.

Aerobic stability is an important feature in the evaluation of silages. The aims were to investigate the chemical and microbiological changes that occur in sugar‐cane (Saccharum spp.) silage after aerobic exposure, to identify the major species of yeasts associated with the aerobic deterioration process and to select lactic acid bacteria (LAB) strains that can improve the aerobic stability of this silage. Fourteen wild LAB strains belonging to Lactobacillus plantarum, L. brevis and L. hilgardii were evaluated using experimental silos. Silage samples were collected at 0, 96 and 216 h after aerobic exposure to determinate the DM, WSC, pH, products of fermentation, to evaluate the silage temperatures and to identify yeast species associated with the aerobic deterioration of silage. The strains tested were able to modify the fermentative and chemical parameters and the diversity of yeasts species of silage after aerobic exposure. There was no association between the facultative or obligatory heterofermentative fermentation patterns and the increased aerobic stability of silage. Aerobic stability of sugar‐cane silages was associated with high acetic acid and 1,2‐propanediol concentrations. L. hilgardii UFLA SIL51 and UFLA SIL52 strains promoted an increase in aerobic stability of silage.

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