Carbohydrate metabolism

What are the products of fermentation?

Acetate from fiber, propionate from starch, and butyrate

Where are VFA's absobed?

into the portal vein

What happens to VFAs before they can enter the portal vein?

They enter the epithelium cells and undergo activation. This process adds a CoA

Why do VFAS undergo reactivation in the rumen epithelium?

so that they cant re-enter the rumen

What does butyrate undergo in the rumen epithelium?

ketogenesis

What is ketogenesis?

The production of ketone bodies for energy

What is the most important ketone body?

B-hydroxybutyrate

What does B-hydroxybutyrate energy do?

goes to epitheial cells and any left over goes to the portal vien

In the small intestine what is broken down with what enzyme?

starch with amylase from pancreas

In the large intestine (non ruminants) what happens in the large intestine?

Fermentation of cellulose and starch to the portal vein.

What happens when acetate and B-hydroxybutyrate arrive at the liver?

They enter the peripheral circulation to be used in the Krebs cycle/ as a substrate in fatty acid synthesis

What happens to the energy from acetate after it enters the krebs cycle?

it is the non rumen cell fuel

What happens to the energy from b-hydroxybutyrate after it enters the krebs cycle?

it serves as rumen cell fuel

What happens to propionate in the liver?

it is converted to glucose via gluconeogenesis

What is the most important source of glucose to an animal?

propionate metabolism in the liver

What is gluconeogensis?

the formation of glucose from non-carbohydrate carbon sustances. like propionate

Why is only propionate used for gluconeogenesis?

because butyrate and acetate all carbons are used in the krebs cycle. 2c and 4c respectively

When is gluconeogensis high in ruminants?

after meals because higher availability of propionate from starch

When is gluconeogensis high in non ruminants?

between meals, in strict carnivors, or during fasting/starvation

How is glucose metabolized?

from liver to peripheral circulation where it then goes to TCA/kerbs and FA synthesis.

In non ruminants what is the main source of fatty acid synthesis?

glucose

In ruminants what is the main source of fatty acid synthesis?

acetate and b-hydroxybutyrate