Roll bale is another form of stored forage. Grass is cut and baled while it’s still fairly wet. If it is too wet, it can’t be baled and stored the same as hay. Thus, the proper moisture content for roll bale silage making is around 60 to 70%. The bales are wrapped tightly with 6 layers of 0.025-mm thick plastic film on a bale wrapper. The material then goes through a limited fermentation in which short chain fatty acids are produced to protect and preserve the forage. This method has become popular on some farms. In Japan, the roll bale silage preparation method of fresh rice straw was developed (Fig. 5.6.3), and the animal feed production from biomass resources is expected to make the best use of roll bale technology.