Silage production

SILAGE PRODUCTION

Multispecies mixtures to enhance silage production

The objective of this project was to determine the herbage production and conservation efficiency when grass monocultures or multi-species mixtures are managed for silage production.


Grass silage is the primary forage for the majority of ruminant livestock during the winter in Ireland. The feed value of grass silage is a combination of its intake potential and nutritive value, which is primarily determined by digestibility.


Harvest date, and more specifically plant growth stage, plays a major role in determining the digestibility of the pre-ensiled herbage and therefore of the resulting silage. Whereas herbage yield increases as harvest date is delayed, digestibility correspondingly declines as the sward progresses through its reproductive stages and the ratio of leaf to stem decreases.


Good grazing management is necessary to maintain pasture quality and can also impact on the quality of silage swards. Appropriate defoliation in winter and early spring reduces the amount of dead material in the sward and thus helps promote higher silage digestibility. Humphreys and O’Kiely (2007) found that the ensilability of swards increased with more frequent spring grazings, as indicated by increased concentrations of water soluble carbohydrates.


To date, silage production has been heavily reliant on perennial ryegrass swards combined with high nutrient input. This system can be costly if there is a need for more regular reseeding, as well as meeting the requirement for higher nutrient input. It has been suggested that multi-species swards may be just as productive as ryegrass swards but with less nutrient input due to the fixing of atmospheric nitrogen by legumes and the effects of interspecies competition (Connolly et al., 2009).

However, it is not clear how a diverse mix of species will interact under ensiling conditions and how they will correspondingly respond to nitrogen (N) input, primary growth harvest date and number of spring grazings, relative to more conventionally managed monocultures of perennial ryegrass or other grass species. The following experiments aim to assess the performance and quality of herbages harvested from multi-species swards grown for silage production under a range of management conditions.

The field plots for this study are located at Teagasc, Grange, Dunsany, Co. Meath. Thomas Moloney is undertaking a PhD on this research. For further information on this task contact Padraig O’Kiely at This email address is being protected from spambots. You need JavaScript enabled to view it. or phone 353-(0)46-9061131.

References

Connolly J., Finn J.A., Black A.D., Kirwan L., Brophy C. and Lüscher A. (2009). Effects of multi-species swards on dry matter production and the incidence of unsown species at three Irish sites. Irish Journal of Agricultural and Food Research 48: 243–260.
(pdf)

Humphreys J., and O’Kiely P. (2007). Effects of two mixtures of perennial ryegrass cultivars with contrasting heading dates, and differing in spring-grazing frequency and silage harvest date, on characteristics of silage from first-cut swards. Grass and Forage Science 61, 77-88.
(pdf)