The Cornell University ruminant physiologist Peter J. Van Soest has stated "As a result of evolution, ruminants have probably adapted to efficient gluconeogenesis, while the lower digestive tract has adapted to the lack of sugar and starch. The true diet of the ruminant is not what it eats, but rather, the combination of fermentation products and fermented feed that escapes from the rumen. The net changes in the ingested feed include conversion of dietary protein and nitrogen into microbial protein, and conversion of carbohydrate into a variety of non-carbohydrate products."
Uhlenhopp, Eldon K.
"Isoacids In The Ruminant,"
Iowa State University Veterinarian: Vol. 49
, Article 2.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol49/iss1/2