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.

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)

Dietary From:

Triglyceride (TG): glycerol + 3 fatty acids

Di-: glycerol + 2 fatty acids

Mono-: glycerol + 1 fatty acid

Phospho-: glyceride + 2 fatty acids + phosphate

Glyco-: CHO group

Sulfo-: SO4

Lipoprotein: contains protein

1. low density lipoprotein (LDL) = ­ lipid, ¯ protein (bad cholesterol)

2. high density lipoprotein (HDL) = ¯ lipid, ­ protein (good cholesterol)

Other Lipds

Waxes: esters of fatty acids and long chain alcholos

Steroids: insoluble in water

*basic structure

Cholesterol - precursor for sex hormones

Carotenoids - carotene - yellow pigment of veggies (Vit. A precursor)