Quality of Silages from Intensively Managed Permanent Meadows
Photo: G. Brändle,
Agroscope
While botanical composition, growth cycle and phenological stage are integral factors, they are not the sole determinants of the quality of grass silages from intensively managed permanent meadows.
In 2018 and 2019, forage was harvested from a Swiss network encompassing a total of 21 intensively managed permanent meadows over a maximum of 5 growth cycles to study its ensilability as well as the fermentative quality of the silage obtained from different growth cycles with permanent meadows of varying botanical composition according to a realistic mowing schedule.
Growth cycle and stage of development influence fermentative quality
Silage quality was highly variable, but predictable from the forage fermentation coefficient estimated based on dry matter and soluble sugar content, as well as buffering capacity.
Growth cycle and stage of development are intrinsically linked in management practices of permanent meadows. They influence forage chemical composition and hence the availability of substrates (mainly water-soluble sugars) and inhibitor concentration, thereby influencing the fermentative quality of grass silages. Botanical composition also influenced the fermentative quality of grass silage, but the differences between botanical types were less definitive than those associated with the other factors investigated in this study.
The analysis of pH, volatile fatty acids and alcohols is essential for the detailed characterisation of silage fermentative quality. Concentrations of the different compounds are correlated. Taken together, they provide an overview of the fermentative processes occurring during ensiling.
Nevertheless, the wide variability in the fermentative characteristics of the silages remains largely unexplained by the factors considered in this study.
The unexplored effect of epiphytic microflora
The microorganisms that inhabit the surface of plants in grasslands, including bacteria, yeasts and moulds, remain an understudied aspect that could also explain some of the variability in the fermentative characteristics of grass silages. The exploration of these microbial communities, now made more accessible by high-throughput DNA sequencing techniques, could provide novel insights for a more comprehensive understanding of the factors influencing the quality of silages derived from permanent meadows.
Conclusions
- This study highlighted the wide variability in the chemical and fermentative characteristics of silages from different intensively managed permanent meadows according to Swiss practices.
- The chemical composition gives an indication of the fermentability of the forages and may serve to predict the fermentative quality of the silages.
- Nevertheless, the variability of the chemical and fermentative characteristics of grass silages remains largely unexplained by the combinations of factors considered in this study, including growth cycle, stage of development at time of mowing, and meadow botanical composition.
- Understanding the agroecological mechanisms that determine chemical composition, the fermentation process and the quality of grass silage remains important for the continual optimisation of meadow management to meet specific objectives.
Bibliographical reference
Analyse multi-facteurs de la qualité des ensilages issus des prairies permanentes à utilisation intensive.
