Effect of processing soybeans on their use by calves.

Full-fat soybeans processed by grinding, roasting, or heating by microwave were used to supply the protein in rations fed Holstein calves. Nitrogen digestibilities of the rations were not significantly different. Nitrogen retention for the roasted soybean ration was higher than that of raw or microwave-heated soybean rations. Nitrogen solubility of the roasted soybeans was lower than that of the other soybeans. Protein hydrolysis, as measured by a new in vitro technique, was higher for the roasted soybeans than for the raw or microwave-heated beans. There were no significant differences in the digestibilities of dry matter, ether extract, or nitrogen free extract among the three rations. Digestibility of crude fiber was lower for the roasted ration than for the other rations.