Water-Soluble Carbohydrates of Cool-Season Grasses: Prediction of Concentrations by Near-Infrared Reflectance Spectroscopy and Evaluation of Effects of Genetics, Management, and Environment.

The study focuses on determining the concentrations of water-soluble carbohydrates (WSCs) in cool-season grasses and how factors such as grass species, time of day, and fertilization affect them. This information is important because high levels of WSCs can negatively affect horses prone to certain medical conditions. Using near-infrared reflectance spectroscopy, the researchers were able to predict WSC concentrations with 90% accuracy.

Overview of the Study

• The researchers sought to develop a method to predict WSC levels in cool-season grasses using near-infrared reflectance spectroscopy (NIRS).
• The study focused on four cool-season grass species — tall fescue, Kentucky bluegrass, orchardgrass, and perennial ryegrass — and 10 cultivars.
• Samples were collected every two to four weeks from plots with or without added nitrogen, both in the morning and in the afternoon.

Results of the Research

• Using a sample subset, the researchers were able to develop an NIRS calibration that predicted WSC concentrations with 90% accuracy.
• The study found that WSC concentrations were influenced by an interaction of species, nitrogen treatment, time of day, and harvest date.
• A moderate positive relationship was observed between photosynthetically active radiation and WSC concentration when both morning and afternoon samples were considered.
• On most harvest dates, the highest WSC concentrations were found in perennial ryegrass or tall fescue.
• Higher WSC cultivars included ‘Aberzest’ and ‘Calibra’ perennial ryegrass, ‘Ginger’ Kentucky bluegrass, and ‘Bronson’ and ‘Cajun II’ tall fescue.

Implications of the Findings

• The study found that it may be possible to minimize WSC intake by horses through the choice of cultivar, time of grazing, or frequency of mowing.
• WSC levels didn’t exceed 150g/kg of freeze-dried weight, which the researchers suggest could be due to the method of testing, the time of sampling, or the process of defoliation.