Formic Acid as a Silage Preservative for Milking Cows

Abstract
Two experiments compared orchard- grass made into direct-cut silage with formic acid, wilted silage with formic acid, or untreated wilted silage. The forages were wilted to 34% dry matter in 1967 and 47% dry matter in 1968. Digestibilities in sheep were determined on the three silages and untreated direct- cut frozen forage in 1968. In each year, the silages were fed to 18 Holstein cows for 120 days in six 3 x 3 Latin squares to measure silage intake and milk produc- tion. Residual sugar in wilted silage was doubled by formic acid treatment and was intermediate in direct-cut silage. Re- covery of dry matter as wilted silage from the silo was improved by formic acid in 1967. Digestibilities of energy, cell walls, acid detergent fiber, and nitrogen were greater in direct-cut silages than in the wilted silages. In 1968, digestibilities of fresh forage and direct-cut silage were equal. Digestibilities were similar for treated and untreated wilted silages. Milk production and fat-corrected milk pro- duction were higher on direct-cut than wilted silages. Intakes of digestible energy from silages were slightly greater for silages treated with formic acid.