Ethanol-Soluble Carbohydrates of Cool-Season Grasses: Prediction of Concentration by Near-Infrared Reflectance Spectroscopy (NIRS) and Evaluation of Effects of Cultivar and Management.
Authors: Kramer Kelly J, Kagan Isabelle A, Lawrence Laurie M, Smith S Ray
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Ethanol-soluble carbohydrates (ESCs)—including simple sugars and fructans—are a recognised risk factor for pasture-associated laminitis, yet measuring them in fresh grass samples has been labour-intensive, limiting practical management decisions around turnout timing and grazing rotations. This research developed and validated a rapid NIRS calibration using 323 samples across four common cool-season grass species (orchardgrass, Kentucky bluegrass, tall fescue, and perennial ryegrass) and 10 cultivars, achieving over 95% accuracy; the researchers then applied this tool to predict ESC concentrations in 1,532 samples across two growing seasons in Kentucky. Afternoon grazing carried significantly higher ESC concentrations than morning grazing across all cultivars tested—a finding consistent with the diurnal accumulation of carbohydrates from photosynthesis—whilst nitrogen fertilisation had minimal effect on ESC levels in most cases. For practitioners managing horses at risk of laminitis, NIRS-based monitoring offers a practical means of timing turnout to low-sugar windows and comparing cultivar suitability, though results from temperate maritime climates may differ from this US-based data, and local validation would strengthen confidence in management recommendations.
Read the full abstract on PubMed
Practical Takeaways
- •NIRS can reliably predict ESC levels in cool-season pastures, enabling rapid assessment of laminitis risk without waiting for lab results
- •Pasture management should consider timing of grazing; afternoon turnout poses higher ESC exposure risk than morning grazing when ESC levels are lower
- •Nitrogen fertilizer application does not significantly alter ESC concentrations, so alternative management strategies should be prioritized when reducing laminitis risk in susceptible horses
Key Findings
- •NIRS calibration achieved >95% accuracy for predicting ethanol-soluble carbohydrate (ESC) concentrations in cool-season grasses using 323 samples across four grass species and 10 cultivars
- •ESC concentrations were consistently higher in afternoon samples compared to morning samples across all cultivars studied
- •Nitrogen application did not significantly affect ESC concentrations in the majority of samples tested