ANS 252 NCSU Exam 2

Animal Nutrition 252 ncsu Exam 2 review

Energy metabolism in Rumen

Microbial Enzymes & SCFA

Energy metabolism abomasum

Digestive enzymes

Energy metabolism Small Intestine

Protein from feed and microbes

Energy metabolism Hind gut

Microbial Enzymes

Energy metabolism last step

Fermentation of SCFA
Causes bloat in the animal
Produces heat and maintains cows body temp

Rumen

100 to 200 liters in rumen compartment
Anaerobic environment
Diverse microbes
Provides housing for microbes and feeds it cellulose
Microbes provide SCFA and protein

Herbivores "nutritional symbioses" anaerobic

Bacteria 10^11/ml
Protozoa 10^4
Fungi < 10^3

Major source of metabolizable energy for ruminants

SCFA

Main source of energy for non-ruminants

Glucose

Main source of metabolizable protein

Microbes

SCFA in microbial fermentation

Acetic acid
Propionic acid
Butyric acid

Lipogenic - goes to adipose tissue

Butyrate
Acetate

Gluconeogenic - covered back to glucose

Propionate

pH important in gut

high pH \= more basic \= ex. acetate
low pH \= more acidic \= ex. acetic acid

High fiber diet

Increases cellulose \= increases acetate

High starch diet (or grain)

Lower pH (rumen acidosis) \= Higher propionate
Rapid fermentation and disruption in ruminal function
SCFA and lactic acid production

Subclinical Rumen Acidosis (change in pH)

pH ~ 5.5
Decreased intake, gain and FE
Occurs without physical indicators
Irreversible animal will die from it

Clinical Rumen Acidosis

pH < 5.0
Increased lactic acid
Metabolic acidosis
Damage to papillae in SI
Microbial death and release of endotoxins
Can be reversed if caught in time by physical indicators

Rumen acidosis can cause these issues

Parakeratosis (hardening of papillae \= drop in absorption)
Liver abscesses (high acid is pulled from gut)
Laminitis (inflammation between hoof and bone of cow)

Prevention of rumen acidosis

Reduce grain (starch \= decrease propionate) replace with fiber (increase acetate)
Feed additives (buffers)

Glucose homeostasis

Ruminants: 50-80mg
Simple stomached animals: 80-120mg

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Reduced glucose fluctuation due to gut fill size, more time ruminating, prolonged digestion, steady VFA production, continuous gluconeogenesis (propionate)

Ruminants and glucose

From by presence of propionate, amino acids, lactic acid, glycerol

Propionate

More than 70% of energy in animal

Dairy cow diet feed

50% forage + 50% grain

Source of glucose: diet 25% + gluconeogenesis 75%

Fatty acids

a hydrocarbon chain with 2 or more carbons and a carboxylic acid group at one end

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Saturated: SCFA, MCFA, LCFA< vLCFA Unsaturated: Monosaturated FA, Polysaturated FA

SCFA

2-5 carbons (soluble in water)

MCFA

6-12 carbons

LCFA

13-20 carbons (generally insoluble)

vLCFA

\>20 carbons (insoluble)

Simple lipids

Fats and oils made of 3 FA each in ester linkage with a single glycerol (triglycerol)

Compound lipid- Glycolipid

Esters of glycerol with a CHO

Maintain cell membrane stability. In animals severe as markers for cell recognition and energy source. Widely found in plants and major lipid in forages.

Compound lipid- Phospholipids

Water insoluble and water soluble regions.
Critical for membrane function.

Compound lipid -Sphingolipids

Abundant in brain tissues
Serve as adhesive sites for proteins, signaling, recognition
Good sources are meat, dairy, eggs

Compound lipid- Lipoproteins

Synthesized in SI and liver.
Proportion of protein varies relates to density.
ex. Chylomicrons, HDL

Acetate produced from metabolism of

CHO, Fat, AA

Are the building blocks for other compounds when in excess

ex. acetate to ethanol

8 Carbon FA

Caprylic acid
Made in the body

Properties that determine FA function

Chain length
Degree of saturation
Location + type of double bond

FA chain length

Fats can have >30 carbons
Volatility decreases with chain length (less likely to evaporate at room temp)

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5-12 C = liquid at room temp 14-16 C = solid at room temp LCFA = higher melting point

FA degree of saturation - Saturated chains

Packed tightly straight structure. Form is more rigid and organized ex. membranes
Higher melting points

FA degree of saturation - Unsaturated chains

Bend (due to kink in structure) packed less orderly, greater potential for movement.

Location of Double Bond + Nomenclature

Omega route go from methyl end to label double bonds.
Delta route go from carboxyl end.

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Saturated: Steric 18:0 Unsaturated: Oleic 18:1, Linoleic 18:2, alpha-Linolenic 18:3 , EPA 20:5, DHA 22:6

Essential Fatty Acids (Indispensable)

Omerga-6 (Linoleic Acid 18:2)
Omega-3 (alpha-Linolenic 18:3)

Higher level of unsaturation

Greater potential for FA to kill microbes

Conjugated Linoleic Acid

t10 (trans double bond at c10), c12 - Anti-Obesity
c9, t11 - Anti-Cancer

What makes cell membrane fluid?

1. Temperature: Cold close together, hot opposite
2. Degree of unsaturation: Saturated FA only single bonds easy to pack, unsaturated 1 or more double bonds.
3. Cholesterol: Cold increase fluidity + flexibility, hot opposite

Lipids in Rumen

Hydrolysis of TAGS
Unsat. FA undergo biohydrogenation
Limit to fat in diet only 8% supplemental fat

Duodenal lipolysis

Pancreatic lipases attaches to surface of triglyceride globules \= FFAs and 2MG

Pancreatic lipase very efficient in these conditions

Neutral pH
Bile Salts
Mixing
Co-lipase

Micelles function

Transport fats and vitamins to enterocyte membrane in highly efficient way.
Increasing surface area

Micelles are made from and do

Small aggregates of mixed lipids.
Carry lipids to epithelial cells in brush border

Chylomicron includes

Apolipoproteins act as cofactors for enzymes or ligands
Phospholipid + cholesterol coating
Core: TGs, cholesterol esters, vitamin ester (90% of weight)

Lipoproteins

Core: TG + Cholesterol
Shell: Proteins + phospholipids

smallest to largest: HDL (good cholesterol), LDL, VLDL, chylomicron (Highest lipid content)

HDL and LDL

HDL highest % of total protein
LDL higher lipid proportion compared to HDL

Where chylomicrons forma and do

In SI mucosal epithelial cells
Transport dietary lipids to adipose tissue

Where VLDL form and do

In hepatocytes
Transport endogenous lipids to adipocytes

What LDLs do

Carry 75% of cholesterol in blood
Deliver to body cells for repair and synthesis

What HDLs do

Remove excess cholesterol from body cells and blood. Deliver to liver for elimination

Lipogenesis

Glucose or AA converted into lipids.
Process is stimulated by insulin.

Intermediary links are glyceraldehyde-3-phosphate and acetyl CoA

Lipids have how much more energy than glucose?

2 and 1/2 times

Ketone bodies form by

Depleted oxaloacetate \= no acetyl CoA entry in citric acid cycle. Acetyl CoA converts into ketone bodies.

Ketogenesis

ketone bodies made from 2 acetyl CoA:
acetoacetic acid, beta-hydroxybutyric acid, acetone

diabetic ketoacidosis

Excess of ketone bodies caused by hormone imbalance of insulin (which is decreased)
in blood \= ketonemia
in urine \= ketonuria

Amino Acid structure

20 AA in living organisms.

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basic amino group (-NH_2) acidic carboxyl group (-COOH) Variable R group (AAs only differ at R group)

Peptide bonds

Bind AAs together (Carboxyl end and amino end of 2 AAs bond to form dipeptide

Non-polar AAs

Hydrophobic
Sulfur AA
Aromatic AA

Polar AAs

Hydrophilic
Uncharged molecules
Major role in metabolism

Basic AAs

Positive charged molecules

Acidic AAs

Negative charged molecules
Big role in removing N from muscle to deliver out as urine

Primary structure

Sequence of AAs and combine with peptide bonds

Secondary structure (alpha-helix)

Arrangement of molecules in structure
ex. DNA

Secondary structure (beta-pleated sheet)

Arrangement of molecules in structure
Pretty flat
ex. cellulose

Tertiary structure

Folding of proteins that gives it 3D look

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Different bonds: Hydrophobic interactions, Disulphide bridge, hydrogen binds, hydrophilic interactions, ionic bonds (+ and + bond together)

Quaternary structure

Polypeptide chains linked together in specific manner
ex. hemoglobin

Protein permutations

20^n (n \= number of AAs).
ex 20 AA equals 400 different dipeptides (20^2 \= 400)

Amphoteric

Molecule can react as both basic and acidic.

Exist as uncharged molecules, ionic charge (dipolar ions), or a mixture, AA in aqueous solution exist as dipolar

Properties of AA

Can act as buffers resisting pH change
ex. acidosis, ketosis etc.
pH value where AA is neutral is known as isoelectric point

What can synthesize proteins from N?

Plants and microbes

Indispensable AA

Need to be included in animal's diet.

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Arginine, Histidine, Leucine, Tryptophan, Phenylalanine, Methionine, Threonine, Lysine, Valine

Amino Acids

Cannot be stored by body.
Adequate intake is essential for healthy animal.

Protein most expensive ingredient in fed

Supply of AA

Exogenous proteins (digestion and absorption)
2. Tissue protein turnover
3. De novo synthesis

Disposal of AA

Oxidation (CO_2 & NH_3)
Ureagenesis (oxidation linked to elimination of N)
Gluconeogenesis i.e. de novo synthesis of glucose

Diet deficient in one AA

Increased oxidation of all AA
Impaired protein synthesis

Adequate diet

Excess in one specific AA
Increased oxidation for only that one specific AA

Limiting AA

AA in shortest supply relative to req.
Usually indispensable: Lys and Met

Pikachurin

Lighting fast and electric properties
Plays big role in how animals see in the retina

'Spiky' Sonic Hedgehogs

Discovered in fruit flies
Provides information for embryos to develop. Helps in separating right brain from left. Makes sure we have two individual eyes

Ranasmurfin

Protein in blue protective foam hat coats tree frog eggs and helps them stick to trees.

Protein catabolism

protein broken down to amino acids by hydrolysis of their peptide bonds. Breaks down protein into 2 separate AA

Deamination

Removal of amino group from AA creates ammonia and organic acid

Transamination

Take ammonia tag it on another organic acid \= amino acid
How animals make dispensable AA

Ketogenic AA towards Acetyl CoA

Lysine
Leucine

AA is supplied by

microbial proteins (captures N from diet) allows microbes to grow.

Ammoniotelic animals

Excrete nitrogen as ammonia

most aquatic vertebrates ex. bony fish and larva of amphibia

Ureotelic animals

Excrete nitrogen as urea
many terrestrial vertebrates; also sharks

Uricotelic animals

Excretes nitrogen as uric acid
birds and reptiles

Energy requirement of Urea synthesis

Requires 6.5 mol ATP/2 mol NH_4^+

Energy requirement of Uric acid synthesis

19 mol/4 mol NH_4^+

Results in birds to have higher body temp, conserve water, maintain low BW. Uric acid is very strong anti-oxidant minimizes neurodegenerative diseases and cancer in birds.