Pre-stretched bale wrap outperforms conventional wrap

14 March 2011

Pre-stretched bale wrap outperforms conventional wrap on baled silage bringing significant savings in terms of time and cost, along with reduced wastage and enhanced silage fermentation, according to findings from new independent research at the Swedish Agricultural University.

Each 2,000m roll of pre-stretched wrap carried 33% more plastic, sufficient to increase output by around 30% or up to 10 bales per roll. Plastic use together with subsequent wastage was reduced by 29% per bale.  The ability to wrap more bales per roll of film thus reducing the number of rolls of film to purchase, handle and dispose of has significant advantages in terms of saving time and money.  Added together, the fewer roll changes, reduced time spent in roll and waste handling, lower logistic costs together with the extra output, and 10% cost savings over conventional film could be made. For contractors, the pre-stretched film has the added advantage of requiring no gear changes.

The Swedish trial featured 132 bales of first cut grass silage comprising an equal mix of round and square bales, half of each were wrapped with pre-stretched Topwrap 2000 and the other half conventional Topwrap. They were stored individually with one metre separation in all directions, covered with netting and checked daily for damage. Samples were analysed after 15 weeks for CO₂ and O₂ content, yeast and mould, DM, pH, sugar and VFAs. In addition, film use per bale, air tightness, temperature inside and outside the bale, bale density and weight loss were also accounted for.

“Despite being lighter film, Topwrap 2000 wrapped bales were relatively similar in silage composition, quality and analysis compared to those wrapped in conventional film,” comments Lars Öhrn product manager for Trioplast on a report from the Swedish Agricultural University. See figure 1. “However one of the most significant findings was that the pre-stretch wrap was approximately 30% more efficient when it came to the amount of film used per bale. Furthermore, pre-stretch wrapped bales recorded a higher CO₂ content which is beneficial for conservation purposes.”

Figure 1: Pre-stretch v conventional film: silage composition, quality and analysis

Source: Swedish Agricultural University

Nsd = no significant difference

“Pre-stretched wrap has been used to make more than 10,5 million bales of high quality silage world-wide.  These new PRETECH products bring together manufacturing expertise, knowledge of raw materials, machinery and silage-making with state-of-the-art technology  and are available in the UK and Ireland offering significant cost benefit opportunities for both contractors and farmers, along with improved silage quality,” says Jeannie Everington of big bale wrapping system pioneer Volac. “Volac Topwrap 2000 is a lighter more durable film which is pre-stretched during manufacture. After stretching, the molecules want to return to their pre-stretched state; they ‘remember’ their original positions which affects the way the bale wrap shrinks back on the bale,” she explains.

“After passing through the pre-stretch unit on the wrapper, film that has already been given a stretch during manufacture will shrink back even further, giving a tighter cling and more effective air-tight seal which encourages enhanced silage fermentation. This was confirmed by the trial findings which demonstrated higher CO₂ levels in the pre-stretch film wrapped bales compared with the bales wrapped with conventional film, thereby enabling better conservation and at the same time preventing clostridia and yeast growth.”

County Antrim based contractor, Brian Darragh, Toomebridge has found that Topwrap 2000 has improved his baling operation’s overall output which adds up to more than 25,000 bales per year. “If all goes well as far as the weather is concerned, we row up and bale on average 500 bales per day using a McHale Fusion 2 integrated baler wrapper.”

The majority of Mr Darrah’s customers request six layers in order to maximise forage quality and avoid wastage, and he reports that the twin wrapper wraps an average 26 bales per roll with Topwrap 2000 compared with 20 bales per roll of conventional wrap. “Consequently, the pre-stretched wrap has brought significant cost savings in that we have been able to reduce the number of rolls used  during an average 500 bale day from 14 rolls of conventional wrap to 10 rolls of Topwrap 2000.

“In addition to purchasing fewer rolls of film, I can use this without changing gears and there is less downtime in changing and handling rolls. Together with the fact that pre-stretch wrap yields approximately 30% more bales per roll, it is helping my baling operation to be much more efficient and economic. Overall, I have been able to reduce wrapping costs by a significant 15p per bale.”

He adds: “The film provides a very tight seal and all my customers over the past two seasons were very happy with their silage results. I am very pleased with the way technology is moving on.”

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