# Feasibility of Utilizing Biodegradable Plastic Film to Cover Corn Silage under Farm Conditions
## 4 Discussion  
The importance of ensuring stable anaerobic conditions to obtain uniform, high-quality silage over the whole profile is unquestionable [3; 33; 34]. The quality of the plastic film used to cover silages plays a key role in the obtained degree of anaerobicis, especially in the 500 to 600 mm peripheral part close to the covering system [4; 9; 35]. The ideal film should have high mechanical and physical properties, high impermeability to oxygen, and costs related to the necessary quality requirements [8]. By the mid-1970s, the use of PE had become the conventional method of covering horizontal silos, and this practice remained unchanged for 30 years. The development of films with similar mechanical characteristics to those of a PE film, but with reduced permeability to oxygen (OB) (obtained by coextruding a layer of barrier polymer), has been shown to improve the quality of corn silage by reducing the yeast count and increasing in aerobic stability [36; 37; 38]. [PERSON] and [PERSON] [9] found, in a commercial bunker silo, that the quality of the silage was improved, over the entire silo face, by use of an OB film, and spoiled silage was minimized (\(<0.6\%\) of the silo surface compared with 5.8% for the part covered with a PE film), especially in the corner areas close to the bunker walls where the DM density was lower and it is more difficult to seal the silos. In the present experiment, the use of an OB film has been confirmed to be a good solution to obtain well-fermented corn silages with a good silage fermentative profile (pH and lactic acid). Moreover, the yeast and mold counts of the silage close to the film were very similar to those at a distance from the film throughout the entire conservation period, that is, until 230 days, whereas the aerobic stability was lower in CF than in FF. These results indicate that apart from a permeability to oxygen, the sealing procedures and the lower density of silage in peripheral areas also play roles in silage aerobic stability [5]. On the other hand, the PE film showed similar values in the FF and CF areas in the first period of conservation, until 133 d, and then started to show significantly higher pH and yeast counts in the CF areas than in the FF ones. Comparing the film  
Figure 8: Aerobic stability of the corn silage, as affected by the time of conservation and the type of plastic cover. Means with a different lowercase letter in the table, within the same column, are different; means with a different uppercase letter in the same row are different. The values at ensiling were not included in the statistical analysis. performances of OB with PE, better fermentation profiles and better aerobic stability appear from 21 d of conservation onwards. [PERSON] et al. [37] also reported a further increase in aerobic stability in silages covered with OB for longer conservation periods than 100 days. Accordingly, in the present work, the aerobic stability increased after 85 days of conservation. In the last few years, there has been a strong pressure to replace petroleum-based plastic films with biodegradable material films [22; 39]. Biodegradable films have been evaluated for this purpose, but their main drawback was found to be their proneness to begin biodegradation during silage conservation [22]. In the present experiment, five different conservation periods (from 21 to 230 days) have been evaluated to verify the effect of MB on silage quality. The MB films showed a positive role in the preservation of silage quality until 85 days of conservation, with similar yeast and mold counts to those of oxygen barrier films, and even better aerobic stability. The use of an MB plastic film in this period allows good silage fermentation, and comparable pH, lactic acid and acetic acid with those obtained when using the commonly used PE and OB films to be achieved. This fermentative profile led to a yeast reduction and improved aerobic stability.