Why would you want to roast them??
They do eat them better when they're roasted. Deer that are not familiar with browsing on growing soybeans are reluctant to eat them whole sometimes.
It helps to soak whole soybeans in water and put them in a feeder, but they'll spoil if not eaten shortly thereafter.
Best way to feed soybeans is to mix soybean meal 50/50 with a complete mineral mix and feed free choice. The mineral will limit consumption but they'll get what they need.
