Bag Silo Densities and Losses

Bag silos made at three research farms in 2000 and 2001 were monitored at filling and emptying to determine densities and losses. A total of 47 bags (24 alfalfa, 23 whole-plant corn) were made, and losses were calculated on 39 of the silos. Dry matter density ranged from 160 to 270 kg/m3. Dry matter density increased with DM content in hay crop silages on average 3.0 kg/m3-% DM whereas the effect in corn silage varied by bagging machine. Density decreased with increasing particle size at 4.1 kg DM/m3 per mm. The operator and how the bagging machine was set up affected density. A wide range of DM losses was observed, 0 to 40%. Average DM losses were 9.2% invisible plus uncollected losses and 5.4% spoilage losses for a total loss of 14.6%. Six silos had excessive spoilage losses of more than 15% and total losses above 25% due to plastic integrity issues or overly dry silage (>40% DM) being fed out in warm weather. Invisible losses were reduced in high porosity silages (where spoilage losses were exacerbated), greater in warm weather, and affected by emptying procedures. Spoilage losses in bags without plastic integrity issues were greater in dry, porous silages, from emptying silos in warm weather, and at lower feed out rates.