CARBOHYDRATES

General: Carbon containing compounds that also contain H & O in the same ratio as water (H2O) CH2O, C6H12O6

Major energy source of the body CHO > fat > protein

Monomer: basic building block. For CHO = monosaccharides; (protein = a.a.)

Glucose- major energy source for most cells. No free glucose is ingested. Enzymes must degrade CHO's to single glucose (mono) units.

I. Monosaccharides: single unit

A. Hexoses: 6 carbon

a. Glucose

b. Fructose

c. Galactose -not free in nature = usually linked to something else

d. Mannose

B. Pentoses

a. Arabinose

b. Xylose

c. Ribose (found in DNA & RNA)

II. Disaccharides

A. Sucrose (glucose + fructose)

B. Lactose (galactose + glucose)

C. Maltose (glucose + glucose; a 1,4)

D. Cellobiose (glucose + glucose; b 1,4)

III. Polysaccharides

A. Amylose

B. Amylopectin (a 1,4 links with a 1,6 branches)

C. Glycogen (same as amylopectin, but much more branching - 2-3 X)

D. Cellulose

 

 

Monogastrics

Source of CHO: plant starch & animal glycogen

Breaks down to glucose

 

 

Digestion & Absorption? Small Intestine

Glucose goes to the liver via hepatic portal vein

In the liver ® glycogen synthsis, energy utilization, main blood supply to go to tissues

 

 

 

Ruminant

Source of CHO: Primarily starch and cellulose

Anaerobic fermentation in rumen!

Starch & cellulose ® glucose ® VFA (propionate, butyrate, acetate), CH4, CO2

 

 

Type of Diet:

High cellulose = increase rumen acetate = milkfat

High starch = increase rumen proionate = gluconeogenic

 

Anaerobic Rumen:

No O2

No electron acceptor

No electron transport

Goal is to regenerate NAD (drives glycolysis and krebs), but in Rumen??

NAD's transfer to pyruvate to form lactate

2 ATP's produced in rumen glycolysis, instead of 6 in cells

CO2 serves as terminal electron acceptor CO2 ® CH4,

Glucose

® lactate ® propionate

® butyrate

® acetate

 

 

 

 

 

 

 

 

 

 

 

Lactate build-up in the rumen:

Lactic acidosis

Acidosis

Grain overload

Laminitis

founder

Cause= abrupt increase in starch intake, increases lactate procuction, decreases rumen pH (6.8 ® 5.0).

Occurs when taken from pasture (roughage) and immediately placed on high CHO (corn) diet.