In trial 1, eight Holstein heifers weighing 410kg were used in an 8×8 Latin square and fed TMR containing 79.3% alfalfa silage and 20% soybeans. The first four treatments were raw soybeans, soybeans roasted and held for 3h at the roasting temperature, extruded soybeans, and soybeans roasted in a California Pellet Mill Jet-Sploder®. The remaining four treatments were obtained by altering the residence time of soybeans in the Jet Sploder®. The temperatures of soybeans exiting the roaster were 117, 126, 138, and 154°C for the last four treatments. The soybeans held 3h postroasting and the extruded soybeans resulted in the highest estimate of postruminal available lysine. Blood plasma concentrations of essential and branched-chain AA were highest in heifers fed soybeans held 3h postroasting. In trial 2, 44 Holstein heifers weighing 150 to 250kg were assigned randomly to one of four TMR. Diets consisted of 91.8% alfalfa silage and 7.5% of one of four soybean treatments. Treatments were raw soybeans, soybeans roasted in a drum roaster with an exit temperature of 146°C, and those roasted with exit temperatures of 141 or 146°C and held for .5h. Estimated postruminal available lysine was higher for soybeans roasted and held versus roasted or raw soybeans. However, BW gain for heifers was similar across diets, averaging .90 kg/d for 12 wk. concentrations of AA in plasma were not affected by diet. Overall, results support the recommendation of holding soybeans for at least .5h following roasting.