DIGESTION SYSTEM Bargfrede

Monogastric (non ruminate) Pigs Chickens Turkeys Dogs Cats Bargfrede

RUMINANTS CATTLE GOATS SHEEP DEER Bargfrede

HIND GUT FERMENTORS HORSE RABBITS OSTRICH Bargfrede

Small intestine (jejunum, ileum) monogastrics Esophagus Stomach Liver Pancreas Duodenum Small intestine (jejunum, ileum) Cecum Colon Rectum Bargfrede mouth > esophagus > simple stomach > small intestine (duodenum, jejunum, ileum) > large intestine > rectum > anus

Mouth Esophagus Monogastrics Mechanical breakdown of foodstuffs by chewing (reduces particle size, increases surface area for action of enzymes). Saliva added as a lubricant and, in some species, contains amylase to begin starch digestion. Esophagus The portal to the stomach Food passes quickly through the esophagus by PERISTALSIS into the stomach. Peristalsis – a process by which muscular contractions propel food material through the digestion tract. Bargfrede

Monogastrics Stomach Liver Pancreas Enzymatic digestion of proteins begins. Foodstuffs reduced to liquid form. Liver Center of metabolic activity in the body. Major role in digestive process is to provide bile salts to small intestine (needed for digestion and absorption of fats). Pancreas Provides a potent mixture of digestive enzymes to the small intestine to help in digestion of fats, carbohydrates, and proteins. Bargfrede

Monogastrics Small Intestine (duodenum, jejunum, ileum) Site of final stages of chemical enzymatic digestion. Where almost all nutrients are absorbed. duodenum (first part of the small intestine) Bile and pancreatic secretions enter here jejunum (second part of the small intestine) Absorption of nutrients ileum (third part of the small intestine) To split food molecules and absorb nutrients Bargfrede

Monogastrics Large Intestine Site of water absorption from G.I. tract. Bacterial fermentation occurs (production and absorption of volatile fatty acids). Somewhat limited in monogastrics Feces formed Remember: the large intestine is shorter in length than the small intestine but of greater diameter and volume. Rectum The last part of the large intestine where feces is stored before going to the anus. Anus Undigested feces that has passes through the body cavity is secreted. Bargfrede

Small intestine (jejunum, ileum) monogastrics Esophagus Crop Proventriculus Gizzard Liver Gall bladder Cecum Cloaca Large intestine Small intestine (jejunum, ileum) Pancreas Duodenum Bargfrede mouth > esophagus > crop > proventriculus > gizzard > small intestine > ceca > large intestine > cloaca > vent

Beak Esophagus Crop monogastrics No lips, no teeth, and no chewing The portal to the stomach Crop Out-pocketing of the esophagus that provides storage pack for consumed food. Saliva assist the foodstuffs tomoistened and softened (little if any digestion). Crop Bargfrede

monogastrics Proventriculus Proventriculus Glandular stomach where the first significant amount of digestive juices are added. This part is also referred to the glandular stomach due to it containing hydrochloric acid (HCL) and digestive enzymes. Proventriculus Bargfrede

Gizzard monogastrics Gizzard A muscular organ used to grind and break up food. May contain grit (small stones) eaten by animal. Most of the fine particles of feed are not retained and move rapidly into the small intestine. Gizzard Bargfrede

monogastrics Small intestine Large intestine Cloaca Vent Major part of digestion and absorption. About 5 feet in length. Large intestine Only 4-5 inches Digestion here happens quickly Cloaca Large intestine joins the vent Serves as a receiving area for the egg in hens. Vent The external opening of the cloaca which allows both egg and waste material to be expelled from the body Bargfrede

RUMINANTS Esophagus Rumen Omasum Reticulum Abomasum Pancreas Liver Gall bladder Cecum Small intestine Large intestine Rectum Bargfrede mouth > esophagus > rumen (regurgitate, rechew, reensalivated, reswallowed) > reticulum> omasum> abomasum > small intestine > cecum > large intestine > rectum > anus

Ruminant Mouth, esophagus, small intestine and large intestine have functions similar to monogastrics. Stomach Structure and function of the stomach is the major difference between monogastrics and ruminants. Multi-compartmented stomach – rumen, reticulum, omasum, abomasum. Bargfrede

Ruminant Rumen (regurgitated, rechewed, reensalivated, reswallowed) Lining of the rumen Rumen (regurgitated, rechewed, reensalivated, reswallowed) The largest of the 4 compartments in the stomach, predominantly on the left side of the body cavity. Active microbial digestion occurs. Covered with papillae to increase the surface area Rumen saturated with gases and in constant motion. Regurgitation: first step in rumination large quantities of roughage are consumed and are chewed just enough to swallow after swallowing, regurgitation (“cud chewing”) takes place, food is re-chewed and the process continues till the food is small enough to travel to the reticulum, the next step in digestion. Bargfrede

Ruminant Reticulum Houses microorganisms Catches hardware (ingested by animal) Provides additional area for fermentation. As fermentation by microorganisms proceed and feedstuffs are digested, smaller and more dense material is pushed into the reticulum (from which it along with microbe-laden liquid is ejected into the omasum). Lining has a honeycomb structure. Hardware can be removed with a rumen magnate. Open to the rumen Bargfrede

Omasum A heavy, hard organ with a lining that has many folds (leaves). Ruminant Omasum A heavy, hard organ with a lining that has many folds (leaves). Function not well understood Believed to produce a grinding action on foodstuffs. May absorb residual VFA’s and bicarbonate. Absorbs mostly water Bargfrede

The true, glandular stomach. RUMINANT Abomasum The true, glandular stomach. Secretes acids and functions very similarly to monogastric stomach. Unique feature is that it secretes lysozyme. Enzyme that efficiently breaks down bacterial cell walls. Needed to break down the large quantities of bacteria that pass from the rumen. Bargfrede

Ruminant Small intestine Cecum enzymatic digestion and absorption Functions of the small intestine: digestion of proteins, carbohydrates, and fats; absorption of the end products of digestion duodenum jejunum ileum Cecum Some microbial fermentation Bargfrede

HIND GUT FERMENTOR Esophagus Stomach Duodenum Small intestine Cecum Large colon Small colon Rectum Bargfrede mouth > esophagus > stomach> small intestine > cecum > large intestine (small colon, large colon)> rectum > anus

HIND GUT FERMENTOR Mouth, esophagus, stomach and small intestine have similar functions as compared to monogastrics. Small and large colon (large intestine) The large intestine of hind gut fermentors is analogous to the rumen in ruminants Microbes digest structural carbohydrates (cellulose, hemicellulose) and soluble carbohydrates that escape digestion in small intestine to Volatile Fatty Acids (VFA’s). VFA’s absorbed from large intestine and utilized by the animal. Microbial protein produced in large intestine is wasted (only very limited absorption from large intestine). Bargfrede

Digestive System Comparisons Function Monogastric Ruminants Hind Gut Fermentors Digest and extract energy from cellulose Very limited (large intestine) Yes (rumen/reticulum) Utilize dietary sugar sources directly (absorbed as glucose) No (fermented to VFA’s) Utilize protein from feeds directly Limited (most converted to microbial protein) Utilize fat from feeds directly Some (most fermented to VFA’s) Utilize microbial protein (60-80% of AA from microbes)

Digestive Tract Capacities Sheep/Goats Cattle Swine Horses Rumen 5-10 gal 55-60 gal ---- Reticulum 1.5 qt 3-4 gal Omasum 1 pt 1-2 gal Abomasum Stomach 2 gal 2-3 gal Small intestine 2.5 gal 17-18 gal 12-15 gal Small intestine length 85-90 ft 130 ft 60 ft 70 ft Large intestine 1.5 gal 10 gal 3 gal 30-35 gal

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