Fructan is a carbohydrate made-up of the simple sugar fructose that is more concentrated in cool season grasses than warm season grasses and has been associated with precipitating laminitis and/or colic. For forages, fructan is a carbohydrate that is important to consider but the amount in the grass will vary with growth stage of the plant. Percent water soluble carbohydrates (WSC) represents sugars, some starch, and fructan content but the problem with using only % water soluble carbohydrates to assess fructan concentration is that one does not know the actual percentage of fructan in the %WSC analysis. Therefore one should use % starch along with %WSC for forage assessment.