I found the 1922 preliminary report on the process along with the 1926 study done on the composition, digestibility and feeding value of the hydrolyzed sawdust.

From the 1926 article: “The method of treatment consists in cooking the sawdust under 120 pounds pressure with dilute sulphuric acid, which converts
a portion of the cellulose and allied substances into sugar. The liquor resulting from the digestion together with the washings from the undigested sawdust residue is neutralized with lime and evaporated to a thick syrup, which is mixed with the dried residue. The product is then ready for feeding. It is a dark brown somewhat powdery meal with a slightly sweet woody odor and a woody flavor.”

Before anyone tries to draw comparisons with “Fresh Horizons” bread from the 70’s, that high fiber bread contained wood pulp and NOT sawdust. And it was banned in Canada.

COWS EAT SAWDUST AND THRIVE ON STRANGE DIET

Making cows eat sawdust, and like it. is the feat of the Forest Products Laboratory, Madison, Wisconsin. A process has developed that converts the fiber of the woody pulp into food for cattle by treatment with heat and chemicals. Its immediate application is seen in utilizing the sawdust that was formerly a useless by-product of lumber camps. Tests indicate that cows and other livestock thrive on the sawdust diet.