Modeling the Effects of Formic Acid and Molasses on Ensilage

Abstract A computer simulation model of the ensilage process is used to study the effect of molasses and formic acid addition on the time course of fermentation and final silage quality. The model simulates the growth and death of lactic acid bacteria and clostridia, hemicellulose hydrolysis, proteolysis, release of ammonia, and changes in water-soluble carbohydrate content, fermentation end products, water activity, and pH. Varying application rates are considered with a range of dry matter contents, buffering capacities, and water-soluble carbohydrate contents for both alfalfa and ryegrass. The results indicate that final silage pH can be either increased or decreased by formic acid addition depending on application rate, crop dry matter content, and other parameters. Final silage pH is decreased by molasses only when the water-soluble carbohydrate content is low enough to inhibit the extent of fermentation. Formic acid is predicted to reduce substantially the extent of proteolysis in silage, while molasses has little or no effect. Both formic acid and molasses reduce the range of conditions resulting in clostridial spoilage, but formic acid ensures a lactate silage with greater certainty.