The nonstructural carbohydrate (NSC) value in forages is an analysis of the simple sugars, fructans and starch content of a plant. This nutritional component is an important factor in horse nutrition as it has been linked to health problems including obesity, laminitis, equine metabolic syndrome and tying up. Much attention has been given to NSC content of forage since it comprises the majority of most equine diets. However, it is important to consider the total amount of NSC in the diet (i.e., forage, grain, treats, supplements, etc.).
A study conducted at North Carolina State University determined the effect of pasture height on pasture NSC and horse grazing preference.
In the fall (November), four mature, idle stock horses with an average age of 8.5 years grazed small pastures containing tall fescue that was mowed to different heights before grazing. Forage heights were short (4 inches), medium (8 inches) and long (12 inches). Pasture height and biomass (yield) was measured in each pasture before horse grazing. Forage samples from each pasture were collected and NSC was calculated. Time spent grazing in each pasture was recorded.
Pasture NSC concentrations were lower for the short compared to the medium and long pastures. Horses spent more time grazing long compared to the shorter pastures and as expected, the taller pastures resulted in more biomass (yield) compared to the shorter pastures.
These results suggest that horses prefer to graze tall pastures that contained greater NSC concentrations. Future research should include different locations, seasons and types of forage. For more information on the research, click here.