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

 

VFA Metabolism

Acetate ® Acetyl CoA = no gluconeogenesis

Butyrate ® 2 Acetyl CoA = no gluconeogenesis

Propionate ® succinyl CoA = gluconeogenesis

VFA's for energy: Acetate, Propionate, Butyrate

VFA's for Fatty Acid synthesis (Ketogenic): Acetate, Butyrate

VFA's for glucose synthesis (Gluconeogenic): Propionate

Blood Glucose Concentration

Monogastric ~90 - 100 mg.dL

Ruminant ~40 - 60 mg/dL

Difference is because little free glucose absorbed in G.I. tract of ruminant, process of synthesizing glucose = gluconeogenesis.

Gluconeogenesis = glucose synthesis from non-CHO sources

Propionate

Lactate

Glycerol

Some A.A.

 

3 Irreversable Reactions of Glycolysis: (otherwise = glycolysis backwards)

1. PEP ® pyruvate Þ pyruvate ® oxaloacetate ® PEP

2. Fructose-6-phosphate ® Fructose-1,6-bisphosphate Þ use different enzyme

3. Glucose ® Glucose-6-phosphate Þ use different enzyme

 

LIPIDS

General: organic compounds that contain C, H, O

Carbohydrates = CH2O

Lipids = more reduced = more H, less O2

More reduced = more energy dense: 2.25 X more (9/4=2.25)

Most feeds contain less than 5% fat

Humans = ~18% fat : 18X 2.25 = 40% calories from fat.

* Ideal = < 30% calories should come from fat, animals not a problem, low fat diet anyhow.

Structure:

CH3(CH2)X-COOH

Non-polar, H3O insoluble

Carboxylic acid = polar, H3O soluble

Short chain: less than 14 carbons

2

acetate

CH3COOH

3

propionate

CH3CH2COOH

4

butyrate

CH3(CH2)2COOH = CH3CH2 CH2COOH

 

Medium and long chain:

Almost all have even number of carbons

Most fatty acids are long chain

Saturated FA: No double bond C (no p bonds) General formula = CH3(CH2)XCOOH

myristate

C14:0

palmitate

C16:0

stearate

C18:0

 

Unsaturated FA: p bonds

palmitoleic

C16:1

oleic

C18:1

linoleic

C18:2

linolenic

C18:3

arachidonic

C20:4

 

Essential FA:

Can not be synthesized by the body, therefore dietary requirement

linoleic

linolenic

arachidonic (the cat can not synthesize)