24/07/2025
Important information on the use of agricultural stretch films
Storage of the stretch films
New and partially used rolls must always be stored in the original carton and upright. The storage location must be dry and protected from heat and sunlight.
Before changing
Ideal feeding stage for the wrapping process:
- Grass at the beginning of ear emergence
- Alfalfa in the young, less woody stage
- Clover for bud formation
Earlier or later timing has an unfavorable effect on the energy content.
Too early: Forage contains reduced nutritional value and little sugar
Too late: Woody stage leads to: Increase in trapped air, poorer forage conservation, reduction in digestibility; Less sugar and increasing crude fiber content disadvantage the fermentation process, which ultimately worsens the silage quality.
The dry matter content (DM content) is also decisive. Ideally, this should be between 35 and 55 %.
A dry matter content of < 35 % may result:
- An unfinished fermentation (especially as the sugar content is low)
- Irregularly shaped bales
- An increase in (possibly toxic) leachate and thus a loss of nutritional value
- Difficult and unstable storage
- Generally poorer preservation
A dry matter content of > 55 % may result:
- Sugar loss
- Change in fermentation
- Increased risk of mold growth
The cut should not be too deep! Cutting heights of seven to eight centimetres - ten centimetres for alfalfa - should be the minimum.
Cutting too deeply can lead to dirt in the forage, prevent rapid resprouting and reduce shading, which leads to more evaporation in the soil.
Preparation and maintenance of the winding machine
In addition to proper maintenance of the winder, the following should be checked in particular:
- The wear condition of wear-prone parts (springs, bearings, rollers, gears, cylinders, etc.)
- The correct lubrication of all elements to be greased (chains, gear wheels, couplings, etc.)
- The rotational speed of moving elements, including the winding plate and arms
- Cleaning the pre-stretch rollers, which must be free of any adhesive deposits
- The height adjustment of the pre-stretching system (align the roller and bale center on a common axis)
- The system setting of the pre-stretcher to obtain a stretching of the film in the longitudinal direction between 50 % and 70 % for round bales and between 55 % and 65 % for square bales
To check the degree of pre-stretching, proceed as follows:
Draw two vertical lines 10 cm apart on the roll before stretching. As soon as the film is stretched on the bale, the distance between these two lines must be between 15 cm and 17 cm for a round bale and between 15.5 cm and 16.5 cm for square bales.
Caution: Pre-stretching is indeed an important component: too little stretching impairs the correct adhesion of the film layers and carries the risk of air penetrating the bale, meaning that preservation is no longer guaranteed. Excessive stretching makes the film too thin and too narrow, it loses its optimum effect and threatens to tear.
The feed press
In order for the wrapping film to be used properly, the compressed bales must be uniform and uniform and have a good compression density. The prerequisites for this are:
- symmetrically shaped swath,
- a press set according to the manufacturer's specifications and
- appropriate conditions of use (good degree of compaction, constant and appropriate speed).
Failure to do so may result in the film tearing during or after wrapping.
Wrapping process
In general, each bale should have at least 6 layers of film at each point of the bale.
Also note the following:
- For woody forage such as alfalfa, apply at least 8 layers of foil
- For continuous wrapping, it is essential to include 2 additional layers for the transition between the bales
- If yarns, netting or blades of grass get caught between the first two layers of film during the wrapping process, two additional layers must be applied to the affected bale until it is actually wrapped airtight.
The film layers should overlap by at least 50%!
Please note: 750 films offer better overlap than 500 films and therefore improve the sealing of the bale and thus good feed preservation even more!
Check regularly during diapering:
- the cleanliness of the pre-stretcher rollers and clean them again if necessary
- the degree of pre-stretching (must be set the same as before winding; otherwise check the winding machine!)
Important:
- Grass continues to “live” even after mowing. Cellular respiration continues in the presence of oxygen and consumes sugar. The nutritional value of the forage also decreases. It is therefore very important to wrap the bale quickly after baling (maximum 2 hours afterwards)!
- Wrapping should not take place in the rain (the moisture reduces the adhesive strength of the film) and not during the hottest hours (heat impairs pre-stretching)
- The adhesive side of the film must always be in contact with the lining!
Handling and storage
Wrapped bales should be moved as little as possible, especially to avoid friction and impacts during storage and transportation. Any handling means a potential entry of air into the bale and a possible loss of nutritional value of the feed.
It is necessary to use tongs or tools specifically designed for handling the bales in order to avoid damaging the bales at all costs!
Any processing must take place in the hour after wrapping or at the earliest 72 hours afterwards! Due to the air pressure in the bale, any intervention from the second to the 72nd hour jeopardizes the impermeability of the film layers and impairs feed preservation.
Round bales should only be stored on the flat side (“upright bales”). Bales with a high dry matter content (between 45% and 55%) should be stacked no more than three times, bales with a low dry matter content (between 35% and 45%) only twice.
We recommend storing the bales close to the farm on a firm and level surface (preferably concreted or asphalted). Whatever the type of storage surface, under no circumstances should the bales be stored on a surface where water can accumulate through holes, watercourses, troughs or drainage. In fact, the film can lose its oxygen and water impermeability properties due to the action of water, which in turn can lead to a reduction or loss of feed quality, even of the feed itself.
The film cannot withstand damage caused by animal attacks (birds, cats, foxes, rodents, etc.). It is therefore essential that all wrapped bales are covered with a protective net suitable for this application, such as the Polytec® bale protection net or Zill silage protection grid, kept closed and protected from rodents by appropriate measures.
Any perforation of the film causes oxygen to enter the bale and impairs the preservation of the ensiled feed. Bales must therefore be checked regularly for holes or other external damage. In the event of perforation, the holes must be sealed with agrifol® special adhesive tape and the feed - provided it is still suitable for feeding - must be used up quickly.
Source: Zill GmbH