Assessing the effect of securing bales with either polyethylene film or netting on the fermentation profiles, fungal load, and plastic consumption in baled silage of grass-legume mixtures

The aim of this research was to study the possibility of reducing mold growth on the surface of low-moisture baled silage, without increasing plastic costs, by replacing polyethylene net with polyethylene tying-film to secure large round bales in the baler chamber. Two trials (I and II) were performed on first and third cuts of the same grass-legume mixture located in the Po plain. In each trial, a total of 16 round bales were baled after 24 h of wilting and half of them were secured with net while the other half were secured with polyethylene film. Four bales from each secure method were randomly assigned to the wrapping layer treatments (four or six layers). All the bales were stored outdoors on their flat ends. After 250 days of storage, the bales were examined to establish their fermentative profile and microbiological quality. Total plastic consumption and costs were also evaluated. The high DM content of the silages restricted fermentation and resulted in low concentrations of acids in both trials, with pH in the inner part of the bale ranging from 5.41 to 5.70. The tying film was well distributed on the curved side and over the edges of the bales and did not show signs of damage due to mechanical operations (ejection, handling, wrapping). The use of tying film, compared to net led to a reduction in the number of holes and an improvement in the anaerobic status of the baled silage, even with just four layers of stretch-film, and resulted in a decrease in mold counts and visible mold growth over the bale surface. It was concluded that securing baled silage with tying film before wrapping could reduce the fungal load of baled silage without increasing the total plastic usage and costs.