Horse and Cattle Digestion

Horse oddities

Unable to vomit Lack a gallbladder Stomach

Esophageal region of stomach- nonglandular

Margo plicatus

Horse-large intestine

Hindgut fermenters-ferment feedstuffs in Large intestine

Cecum- via ileocecal orifice Ventral colon- via cecocolic orifice Dorsal colon Small colon=descending colon

Horse-large colon

Flexures-”turns” in the colon; named for where they are in the abdomen Sternal flexure Pelvic flexure** Diaphragmatic flexure

** Sites of impactions or twists-leads to colic

A=ileumB=CecumC=right ventral colonD=left ventral colonE=pelvic flexureF=left dorsal colonG=right dorsal colonH=transverse colonI=descending colon

Caudal

Cranial

rightleft

Horses-carbohydrate digestion

Carbohydrates-poorly digested in small intestines Needed to feed the microbes in hindgut Excess carbs-highly fermented, leads to

gas production---BAD!

http://www.wcds.afns.ualberta.ca/Proceedings/1996/figures/wc96-058.gif

Horses-protein digestion

Efficiently digested in small intestines Microbes in the hindgut need proteins Liver secretes urea-helps feed

microbes

Horses-

Microbes produce Volatile Fatty Acids (VFA’s) that are absorbed for energy (other animals-what is the primary energy source??) Acetic acid, Proprionic acid, Butyric acids

Acids in the colon still need to be buffered Bicarbonate secreted in colon Cows where is bicarb from???

http://eduforum.ugent.be/vakgroep/fysiologie/theorie/LasMinuteTheo2de2006.htm

Horses-small colon

Absorb electrolytes, water, VFAs

Other nonruminant hindgut fermenters?

Guinea pigs Rats Rabbits Swine

Ruminant digestion

Ruminate their food- Swallow Regurgitate Chew their “cud”=remastication

Breaks down large plant fibers Increase surface area for microbes

Swallow again Cattle, sheep, and goats are ruminants

Rumination

Ruminant digestion

Prestomach vs. True stomach Prestomach

Reticulum Rumen Omasum

True stomach Abomasum

Reticulum

“Honeycomb” Cranial most chamber Ruminoreticular folds Coordinated

contractions with rumen

“Hardware Disease” magnet

Rumen

Fermentation Vat L. side of the cow Muscular pillars with

separate chambers within rumen for mixing

Ruminoreticular contraction- Regurgitation Eructation-escape of CO2 and

methane Bloat

Control of Rumen

Vagus nerve Other factors-rate and strength of

contractions pH Presence of VFAs ( ) Consistency of feedstuffs Stretch receptors

Fermentative Digestion

= protozoal and bacterial action on remasticated plant material Enzymes from microbes! Mammals do not have cellulase! (complex

carbohydrate) Simple sugars (glucose)-

Microbes utilize Convert to VFAs

Absorbed – liver converts to glucose

Microbes also provide Vitamin B and K

Protein digestion

Proteins eaten Microbe converts to peptides, then amino

acids Used by microbes, then converted to:

Ammonia –used by other microbes for protein production

VFAs-absorbed by animal So where do cows get protein????

Liver converts ammonia to urea Bug bodies!! Bypass proteins

Delicate balance

Fermentation balances: Substrate used by microbes (glucose and

peptides) Microbe number Amount of microbes product (VFAs and

ammonia No rapid changes in diet!!!

Omasum

The “book” Break down food

particles further VFA absorption Remove

bicarbonate ions Water absorption

Abomasum

“True stomach” Similar function as simple stomach

animals

Left displaced abomasum (LDA), RDA

Calf digestion

Do calves eat fermentable material??

Rumen/reticulum small and nonfunctional

Reticular groove (esophageal groove)-esophagus to omasum

Ruminants-hindgut Spiral colon

Modification of ascending colon Some fermentation in hindgut!

This workforce solution was funded by a grant awarded under the Workforce Innovation in Regional Development (WIRED) as implemented by the U.S. Department of Labor’s Employment and Training Administration working in partnership with the Colorado Department of Labor and Employment, the Metro Denver Economic Development Corporation, and the City and County of Denver's Office of Economic Development.  The solution was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor.  The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership.  This solution is copyrighted by the institution that created it. Internal use by an organization and/or personal use by an individual for non-commercial purposes is permissible.  All other uses require the prior authorization of the copyright owner.