Wet Fractionation Process: Preservation and Utilization of Pressed Alfalfa Forage

Abstract

Lactation, digestion, and laboratory silo fermentation trials compared wet fractionated alfalfa silage treated with formic acid to conventional low-moisture silage. Eight Holstein and two Ayrshire cows in mid-lactation were fed either the formic-acid treated, pressed silage, or conventional low moisture silage as the only source of forage plus grain according to milk production. Daily intake of dry matter from forage, total intake of dry matter, and 4% fat-corrected milk production were similar for treatments. Ruminal concentrations of acetic, propionic, and butyric acids (molar %) and ammonia nitrogen (mg/100ml) were 61.3, 55.3; 19.5, 21.1; 13.5, 14.8; 18.63, 32.99; for formic-acid pressed silage and conventional low-moisture silage treatments. Apparent digestion coefficients for formic-acid pressed and low-moisture silage were: dry matter 66.3, 67.1; crude protein 71.9, 76.5; and hemicellulose 69.3, 57.4. Pressed forages treated with .00, .20, .35, .50, and .65% formic acid were incubated at 37.8C for 60 days in evacuated plastic bags. As formic acid increased, ammonia nitrogen, nonprotein nitrogen, total volatile fatty acids, and acetic acid decreased while the concentration of cell wall constituents and hemicellulose increased. Lactic acid content increased by addition of .20 and .35% formic acid and decreased when .50 or .65% formic acid was added.