Silage Insights - Research
Re-baling: a suitable method for producing small bale silage and haylage for horses?

By PhD Cecilia Müller

During the last 10 to 20 years there has been an increased interest in feeding baled silage and haylage to horses. However, baled silage and haylage needs to be fed within a few days after opening to avoid aerobic deterioration of the forage. Conventional big bales of silage and haylage, containing about 400-800 kg forage, can create problems for farms and stables housing only a few number of horses, as the daily forage consumption is often low. In fact, more than 75 % of the Swedish horse stables house only one to four horses (Persson, 2005), making it difficult to use big bale silage or haylage. Also, many small horse farms lack equipment to handle big bales easily. Therefore, silage and haylage in small bales is of interest for horse feeding purposes.

One shortfall with the production of small bale silage and haylage is the lack of commercially available machinery equipment adapted for this type of forage production. Due to this, conventional high-density hay-balers are often used for the production of silage and haylage in small square bales, weighing 30-70 kg each. Despite the name, high-density hay-balers often needs to be modified (e.g. exchange of knotters and/or needles) to be able to produce a sufficiently high bale density (kg DM/m³) in silage and haylage bales. Hay bales can and should be porous, while a high porosity (= low bale density) is detrimental for both silage and haylage. Also, handling of small bales in the field during production can be very time consuming and labour intensive. These factors, among others, can make it difficult to harvest the crop in small bales within the harvest window (at a plant maturity giving suitable nutritive value for the horse category in question).

One solution to this problem can be to harvest and ensile the crop in conventional round bales, which are later opened and re-baled into small square bales. This method is also labour-intensive, but has the advantage of a higher field capacity during the harvest. The conventional high-density hay-baler could also be expected to produce a higher bale density, as the crop is already ensiled and will not be as resistant to compaction as a fresh crop. Results from a pilot experiment (see below) using this re-baling method showed average bale densities of 198 kg DM/m³.

The method of re-baling will also put the forage in contact with oxygen in the surrounding air. The question is, therefore, if the hygienic quality and aerobic stability of the re-baled forage will be impaired by this treatment. A pilot study, done at the Swedish University of Agricultural Sciences in 2000-2001, showed that re-baling can be an interesting method for production of small bale silage and haylage, but that big bales containing yeasts may not be a suitable material for re-baling purposes.

The results of the study also showed that the chemical composition of the silage and haylage did not differ between original big bale forage and small re-baled forage, and the general microbial quality was judged to be good, with very low levels of clostridial spores. Also, the temperature in the small bales was stable during at least five days after opening. However, yeast counts were generally higher in small bales, especially if the original big bale had yeast counts detectable in a microbial analysis (above log 1.7 CFU/g fresh forage).

The re-baling method has also been used in a more recent experiment (Müller et al., 2008). In this study, different conservation methods for forage (hay, haylage and silage) and the effect of these forages on hindgut digestion in horses was compared. The haylage and silage in the study was harvested in big bales, and after 6 months of storage re-baled to small square bales. Differences were found between big bale forages and re-baled forages in yeast and mould counts, which were higher in the re-baled forage. However, the general microbial quality was judged as good and the changes in yeast and mould counts were not very large (from log 1.5 to log 3.0 CFU/g fresh forage for yeast, and from log 1.4 to log 1.8 CFU/g fresh forage for moulds). Further validation of existing data and additional studies of the re-baling method are however needed in order to understand the influence of the re-baling procedure on hygienic quality of silage and haylage. It should also be mentioned that both experiments mentioned previously were done when the ambient temperature was below 10°C.

In conclusion, the re-baling method can be an interesting alternative for production of small bale silage and haylage. However caution must be taken as there may be an increase in yeast and mould in the re-baled forage. It is essential that the big bale forage used for re-baling is of very good hygienic quality, that the oxygen exposure time of the forage is kept very short, and that the re-baling location is kept clean.

References:
Müller, C.E., von Rosen, D. and Udén, P. 2008. Effect of forage conservation method on microbial flora and fermentation pattern in forage and in equine colon and faeces. Livestock Science, In Press. Doi: 10.1016/j.livsci.2008.03.007
Persson, P. 2005. Kartläggning och analys av hästverksamheten i Sverige (In Swedish). Rapport, samordningsenheten. Jordbruksverket, Jönköping. ISSN 1102-3007.

PhD Cecilia Müller works at the Department of Animal Nutrition and Management at the Swedish University of Agricultural Sciences, Uppsala, with research and teaching within the area of production and utilization of forages for horses.

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