Benefits from applying additional film layers

Film wrapping costs varies depending on the number of layers of film wrap used, with the conventional 4 layers (50% overlap) being the cheaper:  £1.17 for 4 layers, £1.85 for 6 layers and £2.53 for 8 layers.

The application of an additional 2 layers of film has become more popular in recent years as it has been shown to provide a more robust oxygen barrier resulting in less spoilage of bales by yeasts and moulds, as well as more stable and consistent silage at feed out. Recent research at the Institute of Grassland and Environmental Research (IGER) evaluating film layering at different dry matter contents, provides evidence that increasing film layers result in significant improvements and financial returns.

The IGER experiment shows that applying 6 layers of film significantly reduced mould coverage on the bales compared to applying 4 layers, but applying 8 layers resulted only in a small reduction when compared with applying 6 layers.

Increasing the film layers applied resulted in significantly more dry matter being recovered after the ensiling period. The application of 6 and 8 layers of film resulted in respectively 5 kg and 7 kg more silage DM per bale being retained for feeding compared to 4 layers.
Residual sugar was also greater in response to increasing film layers applied. The improved sugar content was particularly interesting as previous work at IGER has shown that higher sugar levels improve the way the rumen works enabling better conversion of forage protein into meat and milk.  This more efficient utilisation of protein in the silage means not only more production but also results in environmental benefits by reducing nitrogen excretion.

Financial returns
IGER has assessed the financial returns of applying both 6 layers and 8 layers of film when wrapping.  The extra cost which includes the film, its application and disposal was calculated at £0.71 per bale for 6 layers and £1.43 for 8 layers.  The cost saving achieved in terms of the value of the extra dry matter and sugar recovered was calculated at £1.37 and £2.52 respectively which means that the applications of 6 layers gives a return on cost of 92% for 6 layers and 76% for 8 layers. 

Number of Layers Additional Cost Cost Saving Achieved Return on Cost
 6 layers  £0.71  £1.37  92%
 8 layers  £1.73  £2.52  76%
The IGER experiment was jointly funded by bpi.agri, manufacturers of Silotite and Dow.

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