Chitin as an Estimate of Mold in Hay¹

Since studies with food products have shown that chemical quantification of mold is more reliable and repeatable than microscopic procedures, the objective of this study was to evaluate the quantification of mold in hay by the determination of chitin, a fungal cell wall polymer of glucosamine. Alfalfa ( Medicago sativa L.) and alfalfa‐grass hay samples were collected and analyzed for spore count and chitin concentration. Spore counts ranged from 6.8 X 10 5 to 1.8 ✕ 10 7 spores g ‐1 dry matter (DM) and were similar to spore counts previously reported. Chitin concentration ranged from 146 to 592 mg kg ‐1 DM and was similar to those reported for contaminated food products. Chitin and spore count were not correlated (P>0.05). In a second study, core samples were taken from alfalfa bales in which various levels of mold were quantified using a relative mold index (RMI) of 1 = no visible mold to 5 = mycelial mat throughout the bale. Core samples were taken and chitin was quantified in each sample. The chitin concentration ranged from 75 to 464 mg kg ‐1 DM and was similar to chitin concentrations reported in other agricultural products. Chitin and RMI were correlated ( R = 0.81) and residual error was smallest when chitin concentrations were extreme. We conclude that chitin can accurately estimate level of mold infestation in hay.