Bale density and moisture effects on alfalfa round bale silage

Moisture concentration and crop density during fermentation affect preservation of chopped silage, but these variables have not been adequately assessed for round bale silage. The effects of these factors on retention of crop dry matter (DM), silage quality, and nutritive value of alfalfa (Medicago sativa L.) preserved as round bale silage or as dry round-baled hay stored outside on the ground were determined in two field trials. Voluntary intake and in vivo digestibility were also assessed in beef cattle (Bos taurus). Silage bale weights were stable during storage but hay lost an average of 18% of its initial DM during 8 mo of storage. Prestorage alfalfa silage had lower concentrations of neutral detergent fiber (NDF) and acid detergent lignin (ADL) and higher crude protein (CP) and in vitro dry matter disappearance (IVDMD) than hay, probably because of leaf losses during hay harvest. Silage from the higher-density treatment had a pH of 4.76 compared with a higher pH of 5.01 for lower-density bales. Density did not affect lactic acid concentration in silage, but that from the higher-density treatment had more propionic acid at the higher moisture level. Average DM intakes of steers were 17.5, 20.4, and 21.0 g kg^-1 of body weight per day for hay, 594 g kg^-1 moisture silage, and 512 g kg^-1 moisture silage, respectively. In vivo DM digestibility of hay was 592 g kg^-1, lower than the 629 g kg ^-1 average for two silages. Increasing bale density unproved some aspects of silage quality, including a lower pH, but moisture effects on silage preservation were small. Results of two field trials indicate that the round bale silage preservation system saved a greater proportion of alfalfa crop DM and improved nutritive value and forage intake compared with hay.