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How To Cut Silage Damage And Plastic Use On The Farm With HOB Film

Choosing high oxygen barrier (HOB) membranes instead of black PVC panels has been shown to reduce silage clamp losses from 15% to 7%.

This could go a long way toward protecting farmers from rising feed costs.

Burner plates are thin polymer films that stick to the top of the clamp, with the goal of eliminating air pockets.

They’re manufactured using less plastic than traditional blackboards – which are often double-layered – and can only be used with ultraviolet (UV) grille on top, plus weight.

See also: 3 ways farmers use to improve silage management to cut costs

The stove plates cling to the top of the clamp in a similar way to traditional “cling film” plates, but do not require an additional black plastic layer on top.

Manufacturers also claim to reduce silage losses by reducing oxygen penetration. This facilitates the rapid fermentation process and prevents the ingress of air, which in turn prevents the formation of mold.

Tim Brewer of Silostop who specializes in silage protection explains: “A suitable high-oxygen barrier will have an oxygen transmission rate of less than 5cu cm/m² of film. This means that almost no air can get into the clamp used.

‘With this typical black fodder plastic [rate] More than 300 cc / m².

In conventional cling film, he says oxygen transmission can reach 1,000 cc/m² in 24 hours.

This polyethylene is thin and transparent [cling] Films can appear to give a reasonable result, with a visible reduction in damage to the top layer. But a very high oxygen transfer rate leads to high dry matter losses,” he says.

Experimental work at the French National Institute for Agricultural Research (Inra) showed a significant reduction in silage waste from 15% to 7% when switching from black boards to HOB films.

Butyric acid concentrations were also higher in the black plastic-coated grating, indicating poor fermentation.

Cost saving

UK farms showed an even greater reduction in waste, from 15% to 5%. Independent dairy nutrition expert Martin Atwell believes such improvements represent significant cost savings.

For example, in a clamp containing 600t DM of silage at 30% DM, a waste reduction from 15% to 5% will result in an additional 60t DM of silage, he says.

A silage of 11.5 MJ/kg would produce 11500 MJ per ton of DM. If 90% of that energy is going from a tong to a cow, that’s 10,350MJ ME.

High Oxygen Orange Barrier Film With Reusable Cover Anti-UV © Silostop

If 5.3MJ ME were needed to produce a liter of milk, this would likely produce 1.950 liters of milk. And 60 tons DM will produce an additional 117,000 liters.

“At 40p/liter of milk, this represents over £46,000 in additional milk yield. Or, if you want to look at it another way, for every 1 ton DM missing it needs 0.75t of concentrate to replace.

“So if you can save 60 tons of clamp loss, you save 45 tons of extra focus. At £350 a ton, that saves close to £16,000,” Atwell explains.

Moving to HOB film can also help farmers reduce their environmental impact and their use of plastic.

For example, covering feed maize with a single layer of HOB film has been shown to give a significant reduction in primary energy and greenhouse gases compared to covering grates using two layers of standard thick film (see below).


  • -42%
    Waste reduction on top layer of clamps closed with HOB film, compared to black plastic sheet (Meta-analysis of over 50 workpieces, University of Nottingham)
  • > 15%
    Total silage losses on a traditional black plastic film clamp compared to 7% when using HOB (Inra) film

Studies at Wageningen UR Livestock Research have shown that:

  • -82%
    Reducing the overall weight of plastic used when using HOB film versus standard black plastic sheet
  • less than 20%
    The difference in energy required to produce HOB film compared to standard black plastic sheets
  • > 5.5 times
    The amount of greenhouse gases produced in the manufacture of standard black plastic sheet compared to HOB film

Tips to get the most out of your HOB movie

  • Select the appropriate film size for the silage clamps and select the number of joints to avoid air ingress
  • Use an original stove – check by asking questions about oxygen transfer rates
  • Manage films properly: Choose stronger film and a secure cap if clips are frequently filled. A lighter paper with a UV coating is sufficient for filled and left clips
  • Use stove top side panels to reduce the risk of oxygen penetration
  • Follow best silage making practices. In particular, pay attention to uniformity and weight across the clamp. Arrange the sandbags in a 5-meter grid with a double row around the edges. Always cover every evening when harvesting

Case study: Bartletts and Southey Farm, Ilminster, Somerset

Facts about the farm

  • Partnership between Mark Humphrey and his wife Belinda and son Matt
  • Duchy of Cornwall tenants
  • 263 hectares (650 acres)
  • 364 cows produce 8200 liters of cows annually with 4.54% fat and 3.65% protein
  • 3750 liters of cow’s milk annually from the feed
  • Autumn semester – end of August to end of November
  • Triple Cross: Holstein Cross, Norwegian Red Cross, Fleckefe

The use of a high-oxygen barrier film (HOB) eliminated overhead waste on the corn forage buckle, made lids a “breeze” and halved plastic use on Mark Humphrey’s dairy farm.

“I would say we got to zero waste compared to an inch of waste at the top [previously]. It’s not just about quantity, it’s the nuisance factor for removing this contaminated feed,” says Humphrey.

Two years ago, he decided to try using HOB film and an anti-UV coating in place of “cling film,” the traditional black plastic sheets, and green nets.

Although they initially doubted that such a light paper would be strong enough to avoid snagging and do the job without the extra black paper, the system proved its worth.

Corn buckle has side plates, HOB film, UV coating and tire walls or bags of gravel layered in a cross-clamp box style.

Mr. Humphrey found that using less plastic speeded up the lidding process and meant the team was more likely to lie down at night after a long day of silage making.

Forage losses on the previous system are estimated at about 1% or 7.5 tons on a 750-ton corn grate.

Since the rotten silage had to be stripped and disposed of, and good silage could also be removed in the process, he thinks that the total waste could be double or triple that.

Less spoilage also improved ration palatability and dry matter intakes.

The new system uses about 300kg of plastic, about half of that used in turf troughs, where the old system is still in use.

With recycling costs of £220 a tonne last year and environmental pressures to reduce plastic use, the plan is to move the lawn nets to the same system as the green nets wear out and need to be replaced.

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