The Ruminant Digestive System & Nutrition

Ruminant Digestive Systems The digestive system changes food nutrients into compounds that are easily absorbed into the bloodstream.

Ruminant Digestive Systems Ruminants are those animals that contain a multi-chambered digestive system Cattle gain the majority of their nutritional needs from forages and other roughages. Forage refers to grasses, roughages refers to other high-fiber food sources.

Ruminant Digestive Systems Non-ruminant animals cannot obtain the nutritional value from most plant sources unless the food has been modified (ground, mashed, etc.)

Ruminant Digestive Systems The digestive system of ruminant animals starts with: Mouth, Teeth, & Tongue Followed by: Pharynx & Esophagus Mouth - grasps the food Teeth - grind the food Ruminants have only one set of teeth in the front of the mouth (incisors), and two sets in the back (molars). Tongue - covered with finger-like projections (papillae) that contain taste buds. Pharynx - funnels food into the esophagus, preventing food material from entering the lungs. Esophagus - food tube that leads from the mouth to the stomach.

The Ruminant Stomach Rumination: Ruminants are known for “cud chewing” Rumination involves: Bolus of previously eaten feed carried back into the mouth by reverse peristalsis Fluid in bolus is squeezed out with the tongue and re-swallowed Bolus is re-chewed and re-swallowed Ruminant animals grasp mouthfuls of food and swallow it before it is chewed. Ruminants will “chew their cud” (regurgitate) their food material and then grind it with their molars at a time when the animal is resting. This is done until the food particles are small enough to pass through the reticulum into the rumen. Since ruminant animals do not “chew” their food when it is taken in, at times foreign material like rocks, nails, small pieces of wire, can be swallowed. Rumination may occupy about 1/3 of a ruminant’s day

Ruminant Digestive Systems While the animal is “chewing its cud” foreign particles that are heavy are allowed to “sink” in the reticulum, preventing many foreign particles from entering the rest of the digestive system. Once foreign material enters the reticulum, it stays there for the life of the animal.

Ruminant Digestive Systems At this point, ruminant animals have a multi-chambered “stomach” Rumen – the organ that allows for bacterial and chemical breakdown of fiber to gain the proteins and energy from plant sources. Pouch for collection and separation Contains microorganisms (like the rumen) Provides additional area for fermentation As fermentation by microorganisms proceed and feedstuffs are digested, smaller and more dense material is pushed into the reticulum = particle separation Lining has a honeycomb structure Catches and holds hardware consumed by animal. “Hardware Disease” Hardware can be collected and removed with a rumen magnet

Ruminant Digestive Systems The rumen has a very thick, muscular wall. It fills most of the left-side of the abdomen In cattle the rumen can have a capacity of up to 55-65 gallons! Normal 25-30 gallons Large, anaerobic fermentation vat Houses microorganisms Functions of microorganisms Digest roughages Synthesize Volatile Fatty Acids (VFA’s), microbial protein, and vitamins K and B-complex VFA’s absorbed in rumen Lined with millions of papillae (short projections on wall of rumen) needed for absorption “Shag carpet” appearance Rumen saturated with gases and in constant motion Contractions occur several times per minute Serve to mix contents, aid in eructation of gases, and move fluid and fermented feedstuffs into the omasum

Ruminant Digestive Systems The walls of the rumen contain papillae (that can be up to 1 cm. in length), where the bacteria that are used to breakdown fiber live.

Papillae in Rumen

Papillae in Rumen

Ruminant Digestive Systems Next the feed moves into: Reticulum - honeycomb-like interior surface, this part helps to remove foreign matter from the food material. Pouch for collection and separation Contains microorganisms (like the rumen) Provides additional area for fermentation As fermentation by microorganisms proceed and feedstuffs are digested, smaller and more dense material is pushed into the reticulum = particle separation Lining has a honeycomb structure Catches and holds hardware consumed by animal. “Hardware Disease” Hardware can be collected and removed with a rumen magnet

Reticulum - full

Reticulum - cleaned

Tripe = Delicious? People Eat Tripe

Ruminant Digestive Systems Omasum - section that is round and muscular. “Grinds” the food material and prepares the food material for chemical breakdown. A heavy, hard organ with a lining that has many folds (leaves/plies)

Omasum - full

Ruminant Digestive Systems Abomasum - The true, glandular stomach very similar to the stomach of non-ruminants. this is where the majority of chemical breakdown of food material occurs. mixes in digestive enzymes (pepsin, rennin, bile, etc.). The true, glandular stomach Secretes acids and functions very similarly to monogastric stomach Secretes lysozyme Enzyme that efficiently breaks down bacterial cell walls Needed to break down the large quantities of bacteria that pass from the rumen Rennet used in cheese-making

Abomasum – inside view

Ruminant Digestive Systems Followed by: Small Intestine  Large Intestine  Colon Rectum Anus Small Intestine - where most of the food material is absorbed into the bloodstream Large Intestine - begins to prepare unused food material for removal from the body Colon - collects the unused food material that is to be removed from the body Rectum - “poop chute” Anus - opening through which the waste is removed.

Digestive Tract – Bovine Liver Gall bladder Cecum Pancreas

Digestive Tract – Bovine Esophagus Rumen Omasum Reticulum Abomasum Pancreas Liver Gall bladder Cecum Small intestine Large intestine Rectum

Compare the monogastric digestive system with the ruminant system through models (using candy)