Seasonal and Diurnal Variation in Water-Soluble Carbohydrate Concentrations of Repeatedly Defoliated Red and White Clovers in Central Kentucky.

The study examines the seasonal and daily changes in water-soluble carbohydrate concentrations in red and white clovers that have been frequently grazed by horses. The research suggests that these carbohydrates might contribute to unhealthy levels of rapidly fermentable carbohydrates in the horses’ diets and warrants further study to determine if they pose risk factors for the horses’ health.

Objective of the Research

• The primary objective of the research was to study the seasonal and diurnal (day and night) changes in the water-soluble carbohydrate (WSC) concentrations in red and white clovers grazed by horses. This was put under examination because these carbohydrates in pasture plants may contribute to excessive consumption of rapidly fermentable carbohydrates by grazing horses

Research Methodology

• The researchers conducted the study from April to October 2015. They observed the vegetation growth every four weeks and the carbohydrate concentration twice a day, once in the morning, and once in the afternoon.
• Two different varieties each of red and white clovers were selected for the research. These plants were sourced from monoculture plots and were used as representative samples for the kind of vegetation typically grazed by horses.
• WSCs were quantified for each harvest, and starch was quantified for two of the harvests.

Key Findings

• The mean monthly WSC concentrations ranged between 80-99mg/g, while the mean starch concentrations were 31 and 40mg/g, on a freeze-dried weight basis.
• In September, white clover had 14% more WSCs than the red clover.
• WSC concentrations were 10% higher in the afternoon compared to the morning. Contrarily, the starch concentrations were 290% higher in the afternoon than in the morning, and the total nonstructural carbohydrate concentrations in the afternoon averaged around 150mg/g.

Conclusions and Further Research

• Even though the research sheds light on the seasonal and diurnal changes in water-soluble and starch carbohydrate concentrations in commonly grazed clovers, it doesn’t clearly establish if the accumulation is enough to cause health risk factors for horses.
• Therefore, the researchers concluded that additional studies are needed to determine whether the mixed grass-legume pastures of central Kentucky accumulate enough nonstructural carbohydrates to present risk factors for equine metabolic or digestive dysfunction.