Lecture 13 - Digestive Systems Continued

The act of regurgitation, re-mastication, re-salivation and re-swallowing

“True stomach” Glandular -has acidic,enzymatic and mucous secretions

• tissues arranged in a network: “Honeycomb” • traps large particles • collects metal and hardware • next to the heart “hardware disease”

-not completely separated to the reticulum (reticulo-rumen) - left side -largest of the 4 compartments -primary site for microbial fermentation -lined with papillae for increased absorption -storage and “soaking” -microbial protein production Microbial fermentation leads to volatile fatty acids and their absorption which is a source of energy for animal -pH of 6.5 -anaerobic -temp=101-103 degrees

Synthesize protein, B vitamins, vitamin K, and essential fatty acids

Volatile Fatty Acids are short fatty acids • major source of energy by the animal • absorbed by rumen wall

• health benefits: anti-carcinogenic, reduced body fat - synthesized in the rumen

-uppermost : gas - middle : recently ingested roughages - bottom : grain and digested roughages Dependents on gravity

Elimination of gas produced by microbial fermentation in the rumen • eructated gas travel up the esophagus • most of gas is first inspired into the lungs • expired

• leaves of tissues :”pages in a book” • absorption of water and other substances • leaves “squeeze” water from the feeds • regulate water volume of digestion into abomasum • leaves retain particulate matter, fluids move to the abomasum

Similar to the nonruminant stomach • secretion of HCL is relatively greater in ruminants • reduce pH of alkaline contents coming from rumen

Starch : digested by enzymes from small intestine and pancreas Fiber : pass to large intestine (for hindgut fermentation)

• milk bypasses rumen via esophageal groove and goes directly to omasum • grooves contracts and forms a tube which leads to the milk bypassing the rumen and reticulum • muscular fold on the wall of the reticulum

• young ruminant feeds exclusively on milk • consumption of grain and forage leads to establishment of rumen microbial population • the end products of fermentation lead to the development of the rumen