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.

Question?? Acidosis?? Rumen Sample of:

Propionate =

20%

Butyrate =

10%

Acetate =

70%

Not acidosis, propionate from lactate, increase acetate = high forage diet, not a lot of starch

Look at Pro:Ace ratio WHY?

1. Acetic acid ® lost as CH4 = wastefull

2. Propionate ® less CH4 more DE trapped as ME!

Factors that Alter Rumen Fermentation

1. Type of CHO = starch increases propionate, cellulose increases acetate.

2. Feed additives = ionophores, alter Pro:Ace, better utilization of feed. A type of antibiotic = selectively inhibits acetate producing microbes.

monensin = Rumensin

lasalocid = Bovatec

3. Total VFA Produced

a. physical form = ground VS. cracked corn = surface area

b. type of CHO = cellulose VS. starch