Effect of Formic Acid on Recovery, Intake, Digestibility, and Growth from Unwilted Silage

Each of four experiments compared a common source of forage prepared as unwilted silage with no treatment or 0.5% formic acid at ensiling. Two first growth alfalfas and two sudan-sorghum hybrids were used. In each experiment digestibility was determined in 4 4 Latin-square trials, and ad libitum feed intake and growth were measured concurrently in continuous trials with dairy heifers. Animals fed formic silage gained more (P < .025) than those fed untreated silage (588 versus 354 g/day). Mean digestible energy intake was greater (15.8 versus 14.3 Meal/day), and digestible energy intake above maintenance per unit gain was less (11.6 versus 13.9 Mcal/kg) on formic silage than untreated silage in all experiments although these differences were not significant. Energy digestibility was 61.8 for formic silages and 60.6 for untreated silages. Energy digestibility was statistically greater for formic silage in one of four experiments. Gain per metric ton of dry matter ensiled was 122 kg for formic silages and 80 kg for untreated silages. Recovery of energy from the silo was 91.9% for formic silages and 85.6% for untreated silages.