Wet Plant Fractionation: Utilization of Pressed Alfalfa Silage

Abstract

Three lactation trials and two digestion trials were performed comparing mechanically pressed ensiled alfalfa with similar material which was field-wilted before ensiling. Pressed alfalfa contained significantly (P<.05) less dry matter, crude protein, and ash; and more cell wall constituents than the wilted forage, and these trends were transposed into their resulting silages. The pressed silage contained a greater (P<.05) concentration of acetic and butyric acids and nonprotein nitrogen than the wilted silage. Lactic acid concentration in the pressed silage tended to be lower than that of the wilted silage. Over the three lactation trials, silage dry matter consumption, production of milk, and 4% FCM were an average of 8.9, 6.3 and 7.5% lower in animals fed pressed silage. Supplementation of the silage-based diets in Lactation Trial 3 with 2 kg of alfalfa hay increased the total dry matter intake of both groups but didn't alleviate the difference in intake between the two silages. The percentage of rumen acetic acid was higher while that of propionic acid was lower in the pressed silage-fed animals. Ruminal ammonia concentrations also tended to be lower for this group. Although dry matter digestibility of the pressed silage tended to be lower than that of the wilted silage, the only differences (P<.05) observed were an increase in the digestibility of crude protein and a decrease in that of acid-detergent fiber in Digestion Trial 1.