Bunker silo unloaders: An economic comparison

In the United States, bunker silos are most frequently emptied with a skid-steer loader or other bucket unloader. The value of a milling-type unloader on a typical 100-cow Michigan dairy farm was assessed using DAFOSYM, a simulation model of the dairy forage system. The milling-type unloader was predicted to improve dry matter recoveries 0.5 to 3.7 percentage units in alfalfa and 0.3 to 1.5 percentage units in corn silage dependent on silage densities and bunker unloading rates. This range in improved dry matter recovery and the resulting quality changes increased the annual net return from $275 to $4,816. Under good management, increases in net return from a milling-type device were on the order of $400 to $750 per year. This savings would justify an additional investment of up to $6,000 for this equipment if labor and energy requirements for silo emptying were not affected by the unloading method. If the milling-type unloader increased unloading time by 10%, increases in labor and energy costs would reduce the maximum breakeven investment by $3,480.