Dr. Johannes Thaysen
Consultant for Fodder Conservation and Fodder Quality at the Agricultural Chamber in Schleswig-Holstein, Department of Plant Cultivation

Introduction
Keeping horses healthy means feeding them hygienic, high-quality raw feed that covers their basic nutrient requirements and maintains stable intestinal activity. Too little or poor quality raw feed often leads to life-threatening colics. The horse's airways are prone to allergies or chronic illnesses that are fostered by continuous exposure to dust from low-quality hay or straw. Therefore the preparation of horse silage has become widely accepted. Compared to other types of animals, horses are extremely demanding with respect to the quality of their feed.

What are the key factors to be taken into account in the production of haylage and how can the quality be optimised?

Requirements on the quality of the feed in decreasing order of priority:

  • free of yeasts, moulds and their metabolic products
  • no contamination, sand/soil and dust
  • no damp feed constituents (< 35 % DM)
  • no fermenting feed constituents
  • rich structure
  • low concentration of protein and fructanes
  • sufficient levels of energy, minerals and carotene

The fulfilment of these requirements assumes that the following recommendations are followed.

Optimum harvesting time:
Grass crops for horse feed preparation are cut of approximately 50 % of the main constituents of the crop at the beginning of the bloom and when there is a stable high-pressure weather condition. In this stage of development, the grasses have raw fibre contents of 27-29 % and protein contents of <12 %. The utilisation of 3rd or 4th growths should be excluded owing to inadequate wilting conditions or insufficient structural contents caused by the high proportion of leaf.

Hay or silage harvested for feeding dairy cattle that is cut at a young stage is not suitable as a single feedstuff for horses. The use of grass stalks (end of flowering) should be avoided for hygienic reasons and because they do not supply enough energy.

Silage preparation
In practice, the preparation of horse silage is different in many respects compared to ordinary silage: predominantly hay with above-average DM contents is used, with the consequence that there is insufficient protective acidification taking place in the feed. This means that, if there are holes in the bales, there is a strong tendency towards heating and subsequent growth of moulds in the feed.

Many horse owners have misgivings with respect to this DM range because they fear that their horses may react negatively. Recent results from Sweden and much practical experience in Germany show that the opposite is the case: moister feeds are eaten in preference, they contain more digestible energy and thus save on trough feed.

Before the silage is baled or loaded, careful attention must be paid to ensure that no cadavers have been caught up because these can produce botulism toxins. Incidentally, sufficient acidification prevents the production of these toxins over a long time. For this reason, excessive wilting to >60 % DM should be avoided.

Decisive for the quality and storage life of the silage is, as far as possible, quick and complete exclusion of air, which is characterised by a high level of compaction (kg DM/dt silage). For bale silage, this level of compaction is obtained with a baler. The higher the DM content, the higher the level of compaction must be. The target value for 50% DM should be 220 kg DM/dt silage. Cutters on the balers increase the compactability of the silage material and are thus recommended. In addition, square balers have a higher compaction ratio than round balers and should therefore be used in preference for horse silage.

Storage and wrapping
The bales are wrapped immediately after baling with 8 layers of stretch film. Wrapped bales must either be transported carefully to the storage area with special tongs or they should be wrapped directly at the storage area. The bales must be stored on their end face as a matter of principle. The surface under the bales must be inaccessible to rodents, and bales stored outdoors must be protected from insects/birds and effects of water with a tarpaulin. The bales must be continuously checked for damage because any holes in the wrapping always lead to the growth of moulds. Holes in the wrapping must be sealed with a special adhesive tape.

The silage can be used for feeding after a six week storage period.

Conclusions
Correctly prepared horse silage makes excellent fodder for all horses. In contrast to hay preparation, there is no exposure to dust, which has a negative effect and which is not really reduced by moistening the hay.

Grass crops for horse silage must be cut twice a year when the main fraction of the crop is starting to flower, with a cutting height of 10 cm to avoid soil contamination including detrimental microbes, and then left to wilt to a range of 45 to maximum 60% DM. Late hay or fermenting hay with higher DM levels must be avoided by prompt swathing and harvesting. As a quality assurance measure, the DLG-approved silage additives (DLG is a German Agricultural Society) can be added that provide a lasting improvement of the fermentation quality and significantly reduce the residual risk of mould growth.

In case of bale silage, the bales must be wrapped with 8 layers of film and then handled carefully. If the silage is stored outdoors, the silage facility must be secured with silo nets.