The term high sugar grass (HSG) refers to diploid perennial ryegrass varieties which have been bred for an elevated level of water soluble carbohydrate (WSC). These grasses have a large proportion of their ME (metabolisable energy) as plant sugars which are readily metabolised in the rumen.

High WSC levels can be found in many tetraploid ryegrasses. When selecting any ryegrass, there are some critical issues to consider when matching a pasture variety to the dairy farm.