New oxygen barrier stretch film enhances quality of alfalfa wrapped silage

The objectives of this research were to (i) test a new oxygen barrier (OB) stretch film with a 20-fold lower oxygen permeability than the polyethylene (PE) film commonly used on farms to wrap bales and (ii) determine the effects on microbial status, dry matter (DM) losses, and fermentation of alfalfa (Medicago sativa L.) bale silage. Five field trials were conducted on a farm near Turin, Italy. In Trial 1, the bales were wrapped with two, four, six, or eight layers of either conventional PE or OB film. A further four trials were conducted to compare bales wrapped with four layers of OB with bales wrapped with six layers of PE. In the outer layer of bales, the pH was lower in the OB than the PE silages. There was a significant effect of the film type and number of layers on the percentage of bale surface covered by mold (P < 0.001), with less than 15% in bales wrapped with at least four layers of OB film. Storage DM losses ranged from 50 to 123 g kg(-1) DM and were affected by the type of film used (P < 0.001) and by the number of layers applied (P = 0.035), with consistently lower values in OB silages. The new stretch film supports the possibility of conserving high quality alfalfa silage for up to 14 mo, with less film than currently used.