Evaluating the potential of lignosulfonates and chitosans as alfalfa hay preservatives using in vitro techniques.

In our first experiment, we assessed the antifungal activity of two major types of byproducts, one known as lignosulfonates (5 types), which are generated by paper mills, and another known as chitosans (2 types), which are generated from shellfish. These were tested against four fungi isolated from spoiled hay. We observed that acidic conditions are not necessary for chitosans but are crucial to activate the antifungal properties of lignosulfonates. Also, we found that sodium lignosulfonate from Sappi Ltd. was the most antifungal relative to other sodium lignosulfonates from other manufacturers. Chitosans had stronger fungicidal activity than propionic acid or lignosulfonates against all but one mold tested. In our second experiment, we compared the best treatments from experiment 1 against propionic acid using alfalfa hay as a substrate to grow the same fungi tested in experiment 1. None of the doses of chitosan prevented spoilage on high moisture hay, showing results similar to untreated hay. In contrast, an optimized sodium lignosulfonate and propionic acid prevented fungal spoilage of alfalfa hay with doses as low as 0.25%.