Animal Digestion, Ruminant Nutrition, and Digestive Anatomy

Vocabulary flashcards covering monogastric and ruminant digestive physiology, feed byproducts, microbial fermentation, and nutrient metabolism.

Dried Distillers Grains

A feed byproduct originating primarily from ethanol fuel production where corn carbohydrates are fermented into alcohol, leaving behind concentrated protein, fat, and carbohydrates.

Cottonseed Hulls

A byproduct of the cotton industry consisting of outer seed shells and fibrous cellulose that ruminant animals can digest and convert into energy.

Monogastric

An organism possessing a single, simple stomach connected to the mouth by a one-way esophagus, such as humans and pigs.

Abomasum

The true stomach of a ruminant animal where gastric acid enters the digestive system to denature proteins.

Rumen

The large fermentation chamber comprising approximately $80\%$ of a ruminant's digestive tract, housing billions of bacteria and protozoa that ferment feed.

Reticulum

The cranial compartment of the ruminant stomach characterized by a honeycomb lining that stretches and contracts to hold ingested forage.

Bolus

A compacted ball of masticated grass formed in the mouth through circular chewing motions before entering the reticulum.

Rumination

The process where a ruminant brings a bolus back up the two-way esophagus into the mouth to re-chew and further mechanical digestion.

Mucin

A substance contained in saliva that lubricates swallowed food particles throughout the alimentary canal.

Salivary Amylase

A chemical digestive enzyme present in monogastric saliva that begins the enzymatic breakdown of sugars in the mouth.

Concentrate

A grain-based feed source where accessible carbohydrates are concentrated within the inner portion of the seed kernel.

Crop

An anatomical structure in birds where ingested whole seeds are briefly stored before undergoing muscular grinding.

Gizzard

A muscular organ in avian digestive tracts that utilizes swallowed stones or pebbles to mechanically grind tough grains.

Cecum (Horse)

The hindgut fermentation site in a modified monogastric located behind the small intestine, positioning microbial activity downstream of primary nutrient absorption.

Microbial Crude Protein

The primary protein source for a ruminant, composed of rumen bacteria and protozoa that synthesize amino acids from nitrogen and are subsequently digested downstream in the abomasum.

Lysine

A critical essential amino acid that is historically deficient in corn and soybean meal rations fed to pigs.

Hydrochloric Acid ($HCl$)

The gastric acid found in the stomach that denatures complex proteins, lowering gastric pH to approximately $2$ to $3$.

Chyme

The acidic, liquid digestive mixture produced in the stomach before passing through into the duodenum.

Brunner's Gland

A gland situated in the duodenum that secretes alkaline buffers to neutralize low-pH chyme and prevent ulcers.

Duodenum

The initial segment of the small intestine where pancreatic digestive enzymes, bile for fat emulsification, and buffers enter the digestive tract.

Volatile Fatty Acids (VFAs)

Energy-yielding compounds, including propionate, acetate, and butyrate, generated through bacterial fermentation in the rumen and absorbed across the rumen wall.

Propionate

A volatile fatty acid predominantly produced from high-grain diets that is converted into glucose in the ruminant body, yielding white carcass fat.

Acetate

A volatile fatty acid predominantly produced from high-quality forage diets that serves as the biological precursor for milk fat synthesis and results in yellow fat.

Urea Cycle (in Ruminants)

The physiological conservation pathway wherein uncaptured rumen nitrogen is absorbed, processed, and recycled back through the salivary glands to support continuous microbial synthesis.