Agroscope, Institute for Plant Production Sciences IPS, 1260 Nyon, Switzerland

PE colour stretch films for silage bales

Within the scope of an investigation, we examined the suitability of colour PE stretch films for wrapping silage bales. Four types of films (white, black, olive green and brown) of two different manufacturers (Silotite and Teno-Spin) were used. We investigated the temperature rise beneath the film at a depth of 10 cm, the films’ influence on fodder quality, the mechanical and physical properties of the new films as well as their quality after a storage period of 10 months. With peak temperatures of 25 to 30 °C, the upper silage layer of 10 cm beneath the film heated up only slightly. The rise in temperature of the green and brown films was practically the same as that of the white films. The bales wrapped in white film reached a slightly better fermentation quality (higher pH values, higher content of lactic acid) than the other bales. Tensile strength and elongation at break of the two degraded colour films decreased more rapidly than with the white and black films, which indicates that the colour films are less resistant to UV rays. The stronger embrittlement of the colour films was visible. Storage of the round bales during ten months did not have any influence on the films’ gas permeability. Due to the rapid ageing of the colour films, it is recommendable to wrap the bales in six layers and to store them in a protected place (under the canopy of a building, covering them with a tarpaulin)

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