Hay, Haylage and Silage: What’s the Difference?

activity and just like conventional hay bales that are baled in excess of 12 percent moisture heat generation to occur. Forage that is ensiled too dry is a fire risk and can have reduced feed quality due to heating within the bale.
The differences between haylage and silage
Haylage and silage are both ensiled forages but the difference between them is moisture content. In general haylage has a moisture content of between 15 percent to a maximum of 40 percent 60 to 85 percent DM. Silage has a moisture content of more than 40 percent DM less than 60 percent. Both haylage and silage can be found in plasticwrapped round bales. In silage with the higher moisture content the preservation of the forage is as a result of the fermentation of the sugars in the grass under anaerobic conditions. This results in a pH drop. In general a good grass silage in a round bale should have a pH of less than 5. In haylage there isnt sufficient moisture to allow for as much fermentation as in silage. The pH of a haylage round bale will be above 5 on a pH scale of 14. The preservation of the forage in haylage comes from the low moisture content which prohibits microbial growth.
Do all round bales contain ensiled forage? 
All round bales that are wrapped in plastic are either silage or haylage. The plastic is commonly white or light green but can be black as well. The plastic wrap on the round bale provides the anaerobic environment necessary to allow the preservation of the forage through fermentation.
It is extremely important that all round bales fed to any livestock species be wrapped with sufficient layers of plastic. Bales that are not wrapped adequately are more likely to suffer tears and perforations of the plastic allowing secondary bacterial growth. This can contribute to contamination of the bales with yeast mould mycotoxins and spoilage bacteria.
What about preservatives for hay or ensiled feed?
Preservatives like propionic acid can be used to speed up the drop in pH in ensiled forages and prohibit microbial growth in hay that is higher in moisture than ideal. Although propionic acid is safe for horses it is expensive and so not routinely used by growers. Inoculants such as bacterial cultures of lactic acidforming bacteria are used by some growers to facilitate a good fermentation in ensiled forage. Again they are safe for horses