Spring pasture grasses are capable of accumulating high amounts of NSCs, which are implicated in acute equine digestive diseases associated with rapid fermentation and chronic metabolic disorders. | Photo: iStock

As benign as it might seem, this fresh forage can cause more harm than good.

Not all pasture grass is created equal. Although this forage cornerstone of the equine diet offers excellent nutrition, provides fiber to keep the horse’s digestive tract healthy, and allows the horse to satisfy his innate need to graze, come spring it is also notorious for causing causing problems. This is particularly true in horses at risk for digestive or metabolic disorders.

“Spring pasture grasses are capable of accumulating high amounts of nonstructural carbohydrates (NSCs), which are implicated in acute equine digestive diseases associated with rapid fermentation, and chronic metabolic disorders,” says equine nutritionist Bridgett McIntosh, MS, PhD. The types of NSCs found in grasses fall into three categories: sugars (glucose, fructose, sucrose), starches, and fructans.  

“The NSC content of grass varies widely depending on environmental conditions, plant species, and stage of growth,” McIntosh continues. “Through photosynthesis, grasses use light to produce sugars from carbon dioxide. When sugars are produced in excess of the plant’s energy needs for growth and development, they are converted into storage, or ‘reserve,’ carbohydrates