Last program we talked about horses that have foundered or may be insulin resistant and need to be on a low carbohydrate ration.  The specific type of carbohydrate that should be lowered is sugar, starch, and fructans, typically called non-structural carbohydrates, or NSCs.  In the past, it was believed that only the lush pastures were high in carbohydrates and that brown dead grass was low in NSCs and could be grazed by foundered horses.  However, Kathy Watts has done a lot of research on various grasses and has found that during the part of cool season, grasses that are still green can have the highest concentration of carbohydrates in the fall.  Also surprisingly, weeds that were thought to have no nutritional value can be high in NSCs and can cause a horse to founder in a pasture with nothing else than weeds.  Thistles and dandelion have been shown to be high in fructans. 

Another important finding is that grass stems have the highest concentration of NSCs in the entire plant.  Because of this, overgrazed pasture may still have a higher carbohydrate concentration and can cause founder.  Also, the same result occurs by shredding the pasture so this will not help prevent founder in these susceptible animals.  Although we used to think that grass that was drought-stressed had less carbohydrates than lush green grass, recent research shows this not to be the case.  So it is important to be cautious when allowing horses that are susceptible to founder to graze on pasture just because the grass is brown and appears to be dormant.  Also, fertilizing grass was not shown to increase carbohydrate content.  Before allowing founder prone horses to graze a specific pasture, consult with your vet and consider a ration analysis for NSCs.