# Feasibility of Utilizing Biodegradable Plastic Film to Cover Corn Silage under Farm Conditions
## 1 Introduction  
Whole-plant corn silage has become the predominant forage to provide fibre and energy in dairy cattle diets, and it is generally conserved worldwide through ensiling [1]. The success and efficiency of silage depend on the acidification that occurs when, in an anaerobic environment, a sufficient amount of lactic acid is produced by the population of lactic acid bacteria present in the forage at harvesting [2]. The degree of anaerbiosis reached in the filled silo and its maintenance over the entire conservation period are key factors in obtaining a high quality silage [3; 4]. If the air-tight sealing of the silo is not ensured, air penetrates the silage, and aerobic microorganisms multiply, thereby triggering aerobic deterioration and causing dry matter (DM) losses which, in the peripheral area of the silo, can exceed 35% [5]. Therefore, the ensiling technique requires an absolutely air-tight environment which, until the fifties, could only be attained through the use of constructions made of concrete or steel. In those structures, silages were either not covered or covered with organic material, such as manure, with high concerns about the microbial quality of the silages. The introduction, in the early 1950s, of plastic sheeting to cover silage was a milestone of great significance [6] and most silages were covered from the beginning of the 1960's until 2000 with plastic film based on low density polyethylene (PE) [7; 8]. The use of a polyethylene film (125-250 um thickness, including plasticizers and ultraviolet stabilizers to prevent the material from disintegrating under sunlight) became, by the mid-1970s, the conventional method of covering horizontal silos, and this practice essentially remained unchanged for 30 years until the development of co-extruded films with reduced permeability to oxygen [4]. These new oxygenbarrier films (OB), which are made by coextruding a layer of barrier polymer (ethylene-vinyl alcohol copolymer (EVOH) or polyamide (PA)) between two or more layers of low density PE, have shown benefits pertaining to improvements in the quality of peripheral areas in bunker silos as a result of the increased uniformity of the whole profile of the silo during the feed-out phase [5,9]. The main benefits are a better prevention of the growth of pathogenic and mycotoxic models during conservation [10], a delay in their growth after the exposure of the silage to air [11], and a reduction in the DM losses of the overall ensiling system, compared to film made of PE alone [5,12]. On the other hand, the disposal of PE and OB films can represent a potential environmental concern, because they can only be used once, and they are non-biodegradable, difficult to recycle and are rarely disposed of correctly [13,14]. The current disposal methods include transferring silage plastics to a solid waste station or plowing them into the ground, and it often happens that silage plastic covers are burned directly in an open fire on the farms, causing the release of toxic volatile compounds, which are dangerous for human and environmental health [14, 15, 16]. Above all for these reasons, in the last two decades, much attention has been paid to replacing petroleum-based plastic films with cost-effective alternatives, such as organic covers [17,18] or biodegradable materials with suitable mechanical properties [9] to protect silage. New biodegradable plastics, made of renewable resources, are becoming more and more available on the market, thanks to the efforts of chemical engineering and biotechnology companies [13,19]. Bioplastics are defined as those innovative materials that are bio-based (i.e. derived from renewable resources) and fully biodegradable (and which may be completely converted, by microorganisms, into carbon dioxide, water, minerals and microbial biomass, without leaving any potentially harmful substances in the environment).