Development and evaluation of a pelleted feedstuff containing condensed corn steep liquor and raw soybean hulls for dairy cattle diets

A novel product containing raw soybean hulls (RSH) and corn steep liquor (CSL) was developed and evaluated. Feed processing techniques evaluated were: (1) CSL inclusions (0, 50, 80, 100, 120, 150, 200, and 250 g/kg of pellet dry matter [DM]) at the pellet mill conditioner; (2) CSL inclusions (100, 150, and 200 g/kg of pellet DM) using an expander as the sole source of thermal processing; and (3) treating a 200 g/kg CSL inclusion (DM basis) with expander cone pressures of 10.5, 14.0, 17.6, and 21.0 kg/cm2. Improvements in pellet quality were observed with increasing amounts of CSL independent of processing method. However, both pellet durability and electrical energy efficiencies during processing were optimized when CSL was applied at the pellet mill conditioner at a rate to produce pellets containing 750 g/kg RSH and 250 g/kg CSL (raw soybean hull-condensed corn steep liquor pellet (SHSL), DM basis). Increasing the concentration of CSL (up to 250 g/kg of pellet DM) resulted in higher pellet equilibrium moisture contents (EMCs) and reduced the urease activity in RSH. The chemical compositions of RSH, CSL, and SHSL are presented.