White Mould – Causes And Prevention

One of the most frequently asked questions by producers is “How can I prevent white mould in my wrapped silage bales?”.  There could be a number of reasons why white mould appears in your silage bales.  This kind of mould is fairly preventable by making sure that all of the key elements are in place to allow the silage to ferment to perfection.  White mould is usually caused from air penetration into the bale.  Causes could range from using insufficient layers of film; making the bales too loose or damage to the seal during stacking.  Most manufacturers recommend using 6 layers of film for a perfect seal and using more layers is in most cases not economically practical.  However, when wrapping coarser feed or wrapping big square bales, 8 layers is recommended.  Another probable cause may be an over-mature crop or baling at a 65% or higher dry matter (DM) content.  If the product you are baling is too dry and/or over-mature and stemmy, the risk of mould growth increases due to insufficient or non-existent fermentation.

Here in Alberta, the majority of all of the wrapped silage is produced by using what we call “in-line wrappers”.  Most of the white mould found by using this method of wrapping is on the end of the bales or between the bales.  To prevent this from happening, it is important to make the bales equal in size and ensure the bales are dense and cylindrical in shape to ensure a proper seam between the bales.

Quite often, the most common cause of white mould is poor practice. Whenever it appears, most people are too quick to blame the wrap – perhaps because it is the most visible part of the process (unlike the less tangible elements of bacteria or air).  The wrap however is merely a tool and like any tool, it needs to be used correctly to deliver the best results.  Part of this correct usage is ensuring that all of the other basics have been satisfactorily considered and taken care of.  There is a common saying – What you put in is what you get out.  This surely is true when it comes to wrapping bales – you put junk in, you get junk out!

Top Ten Balewrapping Tips

1. Only ensile good quality grass, cut at the optimum growth stage (diagram a) and ideally of 40-50% dry matter (DM). For haylage do not exceed 60% DM. Swath should be uniform in height, density and DM, and the full width of baler pick up (diagram b). Bales should be dense and cylindrical in shape (diagram c).

2. Check that when on the wrapper, the centre of the bale is horizontally in line with the centre of the film reel (diagram d).

3. Check for correct percentage of film pre-stretch by making two marks horizontally 10cm apart on the film reel. Slowly commence wrapping, and locate these marks on the bale surface and measure their distance apart. As an example, for 70% stretch they should be 17cm apart (diagram e).

4. Check on the bale for correct ‘neckdown’. Final film width should be as per (diagram f).

5. Check that film overlap is no less than 50% (diagram g).

6. Ensure that a minimum 4 film layers are applied to all areas of bales up to 50% DM, and minimum 6 layers for those over 50% DM, all square bales, and all bales where the crop is of a coarse nature.

7. Wrap at the stacking area if possible, but if not, move bales from field immediately after wrapping.

8. Never use a spike to stack bales, and repair any damage to bales during the storage period immediately.

9. Protect bales from birds and vermin.

10. Always read film and wrapper instructions before use!

**Top Ten Tips from www.bpiagri.com

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