Here is the real science, from a real scientist, who is involved in doing real science. Please post real science from a real a scientist supporting your stated position.
As per this real scientist at Ohio State U the portion of a chickens' gut that is responsible for the digestion of fiber is only a scant 4 inches long (or about as long as your forefinger) and it is largely nonfunctioning because it has atrophied over millenniums much like your appendix or mine has atrophied from disuse. There is a truism in animal husbandry that states that short digestive tracks are responsible for more food nutrients being lost or pass unabsorbed in the manure.
The part of the below quote in bold italics was highlighted by myself simply to make it easier and clearer for the reader or readers to read and understand. I highly recommend that anyone seriously interested in the welfare of their chickens to click on and view and read this link or similar links. There is a real chickens' digestive system displayed here.
from John Anderson, Dept. of Animal Sciences, The Ohio State University. Used with permission.
http://www.geauga4h.org/poultry/chicken_digestion.htm
"In most livestock, teeth function to grind feed into smaller particles. Birds must pass feed usually whole into the esophagus because they do not have teeth. Therefore, particles of poultry feed should be small enough to pass through the esophagus. Feed passes from the mouth and through the precrop esophagus to the
crop. If the proventriculus and gizzard are full, feed is stored in the crop. Feed is also moistened in the crop.
Feed passes from the crop through the
postcrop esophagus to the
proventriculus. The proventriculus (a glandular type of stomach) secretes acid and enzymes. The acid and enzymes are mixed with the feed to start the digestive process. The feed then passes to the
gizzard (a mechanical type of stomach). The gizzard has very strong muscular walls that grind the feed. Depending on the type of feed ingested, poultry may also swallow small rocks. These rocks aid in the grinding of harder feed particles in the gizzard.
Feed passes from the gizzard into the
small intestine, where additional enzymes are added and digestion occurs. The small intestine also serves to absorb digestion products (proteins, carbohydrates, and fats). You should notice in the photo above that the first part of the small intestine loops around the
pancreas (called the duodenal loop). The pancreas secretes digestive enzymes into the small intestine. The small intestine of a mature chicken is more than 4.5 feet in length, which is necessary to provide the surface area required to absorb digested feed.
Two blind pouches called the ceca (singular: cecum) are attached at the junction between the small intestine and large intestine. Microorganisms capable of breaking down fibrous material live in the ceca. However, this is not a significant part of the digestion system in modern birds. Scientists believe that the ceca may have played an important role in the digestion system of ancestors of modern birds.
The
large intestine of a mature chicken is relatively short, about 4 inches in length. The large intestine stores undigested waste material and absorbs water from the material. The large intestine connects to the
cloaca, which is where the digestive, urinary, and reproductive systems meet. Uric acid is mixed with feces and passes out of the
vent. The vent serves also as the point where eggs pass out of the bird body.
"