Water- and Ethanol-Soluble Carbohydrates of Temperate Grass Pastures: a Review of Factors Affecting Concentration and Composition.
Authors: Kagan Isabelle A
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Understanding the soluble carbohydrate content of pasture grasses is critical for managing equine metabolic health, particularly in preventing pasture-associated laminitis and other nutritional disorders. This 2022 literature review synthesised peer-reviewed evidence from the preceding decade on factors influencing water-soluble carbohydrate (WSC) and ethanol-soluble carbohydrate (ESC) concentrations in temperate grassland, examining how environmental conditions, management practices, and grass genetics interact to shape carbohydrate profiles. Key findings revealed that cool temperatures and autumn–winter seasons consistently elevate WSC concentrations, whilst diurnal patterns show substantial variation (ranging from −20 to 74 g/kg dry matter) with generally higher concentrations in evening hours; however, responses to nitrogen fertiliser, water stress, and defoliation frequency proved inconsistent across different grass cultivars and application rates, indicating no universally predictable outcome. For practitioners—whether assessing pasture risk for metabolically compromised horses, implementing grazing management strategies, or advising on nitrogen fertilisation—this synthesis underscores that soluble carbohydrate content cannot be reliably predicted from single factors alone; instead, veterinarians, nutritionists, and managers must evaluate the interplay of multiple conditions specific to their individual pasture systems and consider direct forage testing when precision is required for high-risk animals.
Read the full abstract on PubMed
Practical Takeaways
- •Monitor pasture carbohydrate content more closely during cooler seasons and late afternoon/evening when horses graze, as WSC levels are higher and laminitis risk increases
- •Implement frequent rotational grazing strategies to reduce fructan accumulation in pastures, which may help mitigate laminitis risk in susceptible horses
- •Recognize that environmental and management factors interact unpredictably—test pasture samples under your specific conditions rather than relying on general guidelines for nitrogen, water stress, or grass variety effects on carbohydrate content
Key Findings
- •WSC concentrations increase under cool temperatures and during cooler seasons in temperate grasses
- •WSC and ESC concentrations generally increase from morning to evening with a range of -20 to 74 g/kg DM
- •Frequent defoliation usually lowers WSC and fructan concentrations
- •Nitrogen application, water stress, and cultivar choice have variable effects on WSC concentration and composition