Comparison of a colorimetric and a high-performance liquid chromatography method for the determination of fructan in pasture grasses for horses.

This study evaluates the reliability of a low-cost colorimetric method versus a costly High-Performance Liquid Chromatography (HPLC) method for measuring fructan levels in pasture grasses for horses. The study concludes that the colorimetric technique fails to provide a dependable substitute for HPLC in determining fructan content in pasture grasses.

The Need for Fructan Determination in Horse Feed

• The study establishes the need through highlighting the health implications of over-consumption of fructan by horses, which is linked to the painful condition of laminitis. Laminitis can be severe enough to warrant euthanasia.
• As fructan levels in pasture grasses, which constitute the majority of equid diets, can vary significantly, accurate quantification is essential for managing horses’ diet, particularly those susceptible to laminitis.

High-Performance Liquid Chromatography (HPLC) vs Colorimetric Method

• High-Performance Liquid Chromatography (HPLC) is often used to measure fructan levels for research purposes, but its high cost makes it not feasible for routine screening.
• The colorimetric method, on the other hand, is frequently used in human food testing and is easily accessible due to its comparative low cost.
• The objective of this study was to test the applicability of the colorimetric method as a low-cost alternative for determining fructan levels in pasture grasses for horses.

Results and Conclusion

• The study involved the analysis of fructan content in various pasture grasses, managed for grazing or conservation, using both HPLC and the colorimetric technique.
• Fructan levels measured by HPLC ranged from 83 to 299 g per kg of dry matter (mean 154), while the colorimetric method measured between 5-238 g per kg of dry matter (mean 82). The discrepancy in measurements varied with the time of sampling and the type of plant species.
• The colorimetric method’s underestimation of fructan content in the pasture grasses was caused by incomplete fructan hydrolysis, thus making it an unreliable substitute for the HPLC method.