Effect of maceration on in sacco degradability and energy content of low-moisture round bale alfalfa silage

The aim of this study was to determine the effect of maceration on in sacco degradability and energy content of low-moisture alfalfa (Medicago sativa L.) silage. The results of two treatments were compared: 1) maceration, in which the alfalfa was processed through a large-scale forage mat maker prior to wilting to approximately 50% DM content (FM treatment), and 2) conventional conditioning, in which the alfalfa was tedded and wilted to the same DM content as that in the FM treatment (CC treatment). Silage bales were chopped in 20-mm pieces for each experiment. In sacco degradabilities of DM, CP and NDF of silage stems were estimated with two fistulated cows incubated for 3, 6, 12, 24,48 and 72 h. DE and ME contents of FM- and CC-treated silage were measured using a respiration chamber with two dry cows. In sacco, DM degradability was similar for both FM- and CC-treated silage, but CP degradability of FM-treated silage was higher than that of CC-treated silage. There were no differences between FM- and CC-treated silage in DE, ME and TDN contents. These results suggested that maceration increased the degradable fraction of CP in the alfalfa stem. However, in chopped silage, maceration has no effects on digestibility and metabolizability of energy.