comp anim nutr2013

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Joelal ACHMADI;Laboratory of Nutrirional Biochemistry;Faculty of Animal Agriculture;Diponegoro University.www.fp.undip.ac.id; [email protected]; [email protected]

ComparativeComparativeComparative

Animal NutritionAnimal NutritionAnimal Nutrition


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comparative animal nutrition 2

Nutrition

The interrelated steps by which a living organismassimilates food and uses it for growth, tissue repair

and replacement, or elaboration of products.

It encompasses all forms of life, including plants andanimals.

It requires the application of chemistry, physics, andmathematics as well as the integration of advancesin soil science, plant science, animal science,biochemistry, engineering, production systems, and

other disciplines.

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Nutrient. Any chemical element or compound inthe diet that supports normal reproduction, growth,

lactation, or maintenance of life processes.

Feed. An edible material that provides nutrients.

Diet. A mixture of feedstuffs used to supplynutrients to an animal.

Ration. A daily supply of feed.

NUTRIENT; FEED; DIET; RATION

Describe examples of each item above [email protected]

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A simplified schematic chart of element and compounds

that may be present to feed1. Protein

2. Nonprotein

1. Essential fatty acid2. Sterols3. Terpenoids

4. Waxes5. Phospholipids6. Miscellaneous

1. Monosaccharides2. Disaccharides3. Oligosaccharides4. Nonfibrous polysccharides5. Fibrous saccharides

1. NitrogenContaining

2. Lipids

3. Carbohydrates

4. Miscellaneous

OrganicCompounds

3. Carbohydrates

1. Essentialelements

2. Possiblyessential

3. Nonessential

4. Often toxic

Inorganic

1. Macro

2. Micro

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a.1. Nitrogen Containing

a.1.1. Protein

a.1.1.1. Essential amino acid : isoleucine, lysine, methionine,phenylalanine, threoline, tryptophan, valine.

a.1.1.2. Semi-essential amino acid: arginine, cystine, glycine,histidine, proline, tyrosine.

a.1.1.3. Non-essential amino acid: alanine, aspartic acid, glutamicacid, hydroxyproline, serine

a.1.2. Non protein

Peptides, amides, amines, nucelic acids, nitrates, urea,many nonprotein amino acids, and hundreds of other

compounds containing N

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a.2. Lipids

a.2.1. Essential fatty acids: linoleic, linolenic

a.2.2. Sterols: cholesterol, vit. D, many other related compounds

a.2.3. Terpenoids: carotene, xantophylls, others

a.2.4. Waxes: cutin, others

a.2.5. Phospholipids: lecithin, others

a.2.6. Miscellaneous: free fatty acids, others







a.2. Lipids







a.2. Lipids

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a.3.1. Monosaccharides: simple pentose or hexose

a.3.2. Disaccharides: sugars with two molecules of simple sugars

a.3.3. Oligosaccharides: sugars with more than two simple sugars but still

relatively small molecules

a.3.4. Nonfibrous polysaccharides: dextrins, starches, pectins

a.3.5. Fibrous polysaccharides: hemicelluloses, celluloses, xylans

a.3. Carbohydrates

a.4. Miscellaneous

Lignin; organic acids; compound contributing to color, flavor and odor;

toxins or inhibitors of various types; animal and plant hormones

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b.1.1. Macro elements: Ca, Cl, K, Mg, Na, P, S.

b.1.2. Micro elements: Co, Cr, Cu, F, Fe, I, Mn, Mo, Ni, Se, Si, Sn, V, Zn

b.2. Possibly essential elements: As, Ba, Br, Cd, Sr.

b.3. Nonessential elements: Ag, Al, Au, Bi, Ge, Hg, Pb, Rb, Sb, Ti

b.4. Often toxic: As, Cd, Cu, F, Hg, Mo, Pb, Se, SI

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Comparative Nutrient Utilization

Rumen microbes could breakphytate

Most dietary P [from plant]could not be utilized

Minerals

Rumen microbes couldsynthesize water soluble vitaminsand vitamin K

Most essential vitamins mustbe supplied

Vitamins

Rumen microbes could degrade

beta-linkage of several glucosemolecules

Ration is limited by dietarycrude fiber [cellulose]Carbohydrates

Rumen microbes undergohydrogenation on unsaturated

fatty acids

Unsaturated fatty acids passthrough G.I. tract wihtout

hydrogenationLipids

Do not require specific amino acidRequire specific amino acidProtein

RuminantNon RuminantNutrient

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Preparation of feed for absorption

Reduction in food particle size

mechanical - chewingchemical - HCl, bile

enzymatic - lipasemicrobial

Digestion

Types of Digestive Systems

Monogastric (Simple stomach): humans, swine, poultry

Monogastric with a functional cecum: horses, elephant, rabbit Ruminant (polygastric - 4 compartments): cattle, sheep, goats

DIGESTIVE PHYSIOLOGY


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Components of Digestive System

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Mouthparticle size reduction by mastication (chewing)

Stomach

storage compartment

physical breakdown of feedchemical digestion (HCl, Pepsin): Acidic pH = 2

* also fermentative digestion in ruminant

Small Intestine (pH ~ 6-7) : enzymatic digestionfrom pancreas, liver, small intestine

breakdown peptides to amino acidsbreakdown CHOs to sugars (glucose)

Absorption of nutrients

Large Intestine

water resorption

storage of undigested foodmicrobial fermentation (limited absorption)


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Comparative Type of Digestive System

Microbial digestionMicrobial digestionLarge intestine

Enzimatic digestionEnzimatic digestionSmall intestine

Physical breakdown

Chemical digestion

Microbial digestion

Physical breakdown

Chemical digestionStomach

Mechanical - chewingMechanical - chewingMouth

RuminantNon RuminantGastrointestinal

Track


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NUTRITIVE FEED EVALUATION

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Nutrient profile must be compared on DM basis.

Extremely variable:Grains70 - 95% DM (30 - 5% water)Forages 5 - 95% DM (95 - 5% water)

DM

water

AS FED basis

[Diluted nutrients]

DM

DM basis

[concentrated nutrients]

VS


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Types of Feed Evaluation:Physical

Chemical

Biological

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Evaluation of Feed Quality :Nutrient profile to determine the amount and/or

concentration of nutrients in a feed or diet [chemicalanalysis]

Nutrient utilization to determine the proportion ofnutrients in a feed or diet that are absorbed from

gastrointestinal tract of animal [a biological trial].


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Nutrient Profile of Feed:Proximate Analyse

AIR DRY SAMPLE

MOISTURE-FREE SAMPLE

CRUDE PROTEIN FAT-FREE SAMPLE

CRUDE FIBER + ASH

CRUDE FIBER ASH

Dry at 105 Co

KJELDAHL ETHER EXTRACTION

ETHER EXTRACT

BOIL IN ACID

BOIL IN ALKALI

BURN IN FURNACE


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Nutrient Profile of Feed:Detergent ExtractionMethods

SAMPLE OF ROUGHAGE

N D S

ACID SOLUBLE

N D F

ACID INSOLUBLE

A D SA D F

Digested in acid detergent

Digested in neutral detergent

Digested in concentrated H2SO4

[Cell content] [Cell wall]

[Hemicellulose,lignified cell wall]

[Lignocellulose]

[Cellulose] [Lignin]


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Nutrient Profile of Feed: Specialized AnalyticalMethods

1. Bomb Calorymetry

2. Amino Acid Analysis

3. Atomic Absorption Spectrophotometry

4. UV-Vis Spectrophotometry

5. Gas Chromatography

6. High Performance Liquid Chromatography

7. Automated Analytical Equipment


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Nutrient Utilization of Feed:Conventional Methods of Digestion Trials

Feed Digestibility

The proportion of nutrients [weight unit] in feed or diet that are absorbed fromgastrointestinal tract.

Coeficient of Feed Digestibility

The expression of feed digestibility in percentage.

Nutrient Digestibility [100%]:

Nutrient intake - Nutrient in feces

Nutrient intakeX 100


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Animals are fed a diet of known composition over a time period, during

which the feces are collected and later analyzed for the components ofinterest.

Maintaining a constant daily feed intake is advisable to minimize day-to-day variation in fecal excretion.

Time required for feed residues to travese the GI tract 1 or 2 days fornonruminant, and 4 to 7 days for ruminant preliminary period of 3days [nonruminant] and 10 days is needed to void the GI tract ofresidues of pretest feed and to allow adaptation of the animal to the

diet.

A collection period of 4 days [nonruminant] and 10 days [for ruminant]follows the adjustment period.

Values can be obtained for apparent digestibility of any desirednutrients, but meaningless for vitamin or minerals that are present inextremely small amounts.

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Total Digestible Nutrients [TDN]

Measure of energy for ruminant.

It comprises of the % digestibility of

+ crude protein

+ crude fiber

+ ether extract [x2.25]

+ nitrogen free extract

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Nutrient Utilization of Feed:Indicator Methods of Digestion Trials

Often a choice when it is impossible or inconvenient to

measure total feed intake or to collect total feces.

It uses reference substance which should be indigestible,nonabsrobable, nontoxic, and easily analyzed in feed and

feces.This methods provides an estimate of digestibility of anyor all nutrients without need to know either the total feedconsumption or the excretion of feces.


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External Indicator

Extensively uses for both nonruminant and ruminant.

External markers or indicators such as chromic oxide or rareearth elements that are either added to the feed or given to

animal orally to animal [or administered into the rumen orcannula]

Internal Indicator

Extensively uses for ruminant.

Internal markers that are present in feed naturally, such as ligninthat is digested to a negligable degree though it is incompleterecovery.

The use of silica have a problem presumably because ofcontamination of soil.


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Apparent digestibility [%]

Amount of feed consumption may be esimated using indicator methods:DMfc [units/day] =

% ind.feed

% ind.feces

% nutr.feces

% nutr.feedX100 X{ }100

X [amount. ind. per unit dry feces]

ind.fd/unit DMfd

If 1% of marker Cr2O3 was added to feed, and the marker Cr2O3 in feces were

3%; 3,1%; 2,9%; and 2,7%

Then estimate the coefficient of feed digestibility!


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The Validity for Results of Digestibility Trials

Major classes of nutrients [protein, fat, soluble carbohydrates], exceptfor fibrous carbohydrates, are also excreted in feces from endogenous

sources, besides from feeds.The apparent digestible nutrients represents the difference betweenthe amount ingested and the amount appearing in the feces.

The true digestibility of a nutrient is the proportion of the dietary intake

that is absorbed from GI tract, excluding any contributions from body[endogenous] sources.

For example, fecal N is derived from feed [not from body tissues] exogenous N; fecal metabolic N is derived from body tissues

endogenous N.

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Nutrient Utilization of Feed:

Methods of Digestion Trials for True Digestibility

It is extensively used for nonruminant, but there is

possibility for ruminant.1. Feeding a nitrogen-free diet and determining theamount of nitrogen excreted in feces.

2. Feeding a completely digestible nitrogen.

3. Feeding several levels of nitrogen andcalculating the fecal level by regression analysis toa zero intake [use specific steps of calculation].


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Steps in calculating true digestibility of a protein

8080True N dig., % [7/1 x 100]8

816True N absorption, g [line1 - line6] [1-6]7

24Unabsorbed dietary N, g [line2 line5]6

11Metabolic fecal N, g5

7075Apparent dig.,% [3/1x100]4

715Apparent N absorption, g [line 1 line 2]335Daily fecal N, g2

1020Daily N intake, g1

Protein Intake

High LowI t e m

LineNo.

To determine true digestibility of a protein, proceed sequenttially through the 8 steps as indicated in thecolumn labeled Line No.. Note that true digestibility is not changed by level of protein intake,eventhough apparent digestibility increased by a high protein intake. [Pond et al., 1995].

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SYSTEM OF NUTRIENT METABOLISM

Metabolism:Catabolism. This is the oxidation of biological fuels to produce

energy in the form of ATP. Oxidation of biological fuels [whichare largely hydrocarbons] ultimately to carbon dioxide and

water is the mechanism for energy release. Some of this energyis lost as heat, but much is captured in the chemical bondenergy of ATP.

Anabolism. This is the synthesis of molecules using energy

supplied in the form of ATP. The molecules which are theprecursors of biological polymers are either supplied in the dietor synthesised within cells. Both processes require energy.

System of Metabolism: a travel of nutrient from feed precurement,

preparation for absorption [digestion], and utilization by body tissue.

Three main nutrients: carbohydrates, lipids, and protein.


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Summary forthe nutrient digestion[in nonruminant]

Protein Lipids StarchLactose

Saccharose

Digested byenzymes ofGI tract

Carbohydrates:Cellulose1,2,3,4- -glucanArabinoxylanGalactomannan

-galactoside

Can be digested only byenzyme of rumen microbes

Stomach

pH1,0-2.5

Pancreatic

pH7.6-8.2

Smallintestine

pH6.5-7.5

Pepsin

TrypsinChymotrypsin

Elastase

Carboxypeptidase

A & B

Alphaamylase

Lipase

Di-, &carboxy

peptidase

Glucoamylase;Disaccharidase

Polypeptides

Polypeptides

Oligopeptides

Polypeptides

Oligopeptides

Aminoacids

Monoglycerides

Fatty acids

GlucoseFructose

Galactose

OligosaccharideMaltose

MaltrioseDextrins

Glucose

Aminoacids

Monoglycerides

Fatty acidsGlycerol

GlucoseFructose

GalactoseGlucose

Absorption fromsmall intestine

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Schematic

representation ofrumnal digestion ofcarbohydrate. Dg =degradable; Ug =undegradable; Hc,Hcell = hemicellu-

lose; C, Cell =cellulose; St =starch; WSC = watersolublecarbohydrate; ATP =adenosintriphosphate; VFA =volatile fatty acids;M, Micr = microbes,microbial; Duod =duodenal. (from :Beever, 1993).

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Carbohydrate Metabolism

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DigestionIn the mouth of nonruminants, amylase from saliva degrades starch to

oligosaccharide units. The amylase saliva randomly catalyses the

breakdown of 1,4-glicosidic bonds in starch. The action of amylase salivais inhibited by a low pH of the stomach.

In the small intestine, the digestion of starch is continued by the action ofamylase from pancreas [amylopsin]. The oligosaccahrides are digested to

monosccharides by the action of disaccharidases.

In ruminants, some bacteria secrete cellulase, pentonase, and othercarbohydases. These intracelluler enzymes catalyse the breakdown ofdietary carbohydrates. Monosaccahrides and disaccharides are rapidlyfermented to volatile fatty acids [VFA], and hemicellulose and cellulose are

fermented more slowly.

Acetic, propionic, and butiric acids are main products of carbohydrate digestionin rumen. The proportion of this VFA depends on the ratio of dietaryroughage to concentrate.


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Absorption of ingested carbohydrates

The cranial part of small intestine have biggest capacity for monosaccharidesabsorption. The lower part of small intestine have more lower capacity for theabsorption, and stomach and cecum have lowest capacity for monosaccharidesabsorption.

In general, glucose and galactose are absorbed with the biggest rate. Theabsorption of glucose and galactose are absorbed via mechanism of active

transport [depending on available energy]. The absorbed glucose andgalactose remain intact relatively after reaching portal vena.

Most of VFA in the ruminant body are from the rumen. The propionic and butiricacids are metabolized in rumen wall and liver; and acetic acid are moved to theperipher circulation. The oxidation of acetic acid mainly occurs in adipose and

muscle tissues of ruminant body.

The order of VFA absorption : butiric > propionic > acetic; the more longer fattyacid is more rapidly absorbed.


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Patways for Metabolism Conversion of Monosaccharides

Some monosaccharides that are not converted to glucose in mucose cell ofsmall intestine throughout absorption will be converted to glucose by some

conversion pathways in liver.

Glucose will be converted to glycogen and then is stored in muscle and livertissues. Glycogen is starch like compound that is ready to be coverted

back to glucose [recall pathway of glucose conversion to glycogen, and

vice versa].

Non carbohydrate compounds are also converted to glucose viagluconeogenesis pathway in liver. Glucogenic amino acids and short chainfatty acid could be converted to glucose via gluconeogenesis.


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The storage of glycogen is limited, when ingested carbohydrate is in excessiveamount over the requirement for glycogen formation, then glucose will be

converted to the fat body. This process is accomplished by breakdown ofglucose to pyruvate, and therefore it is ready for fat synthesis. The conversionof glucose to pyruvate is continued by lactate formation that occurs inanaerobic condition in muscle tissue [recall pathway of glycolisis].

Other route for glucose catabolism via oxidative pathway of phosphogluconate[pentose-phosphate pathway; oxidative shunt; pentose shunt]. Some enzymesthat drive glucose utilization are found in liver, adipose tissue, cell of mammarygland.

The pathway of pentose-phosphate is impportant:1. to allow synthesis of ribose-5-phosphate, the main component of

nucleic acid,2. to allow by passing process for some tissues in glycolitic pathway,

3. to produce nicotine adenin dinucleotide phosphate [NADPH], an

essential reductor in synthesis of fatty acids and reaction ofhydroxylation.


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In ruminants, oxidation of acetate mainly occurs in adipose and muscletissues. Propionate is mainly for glucose synthesis. Propionate plays an

important role for stabilization of blood glucose, especially in ruminant fed onhigh roughage, thus only small amount of glucose is absorbed from GI tract.Some studies reported that more than 30% of propionate from rumen isutilized for glucose synthesis.

After transportation to blood circulation, VFA enters the tricarboxylic acid[TCA] cycle, and is used to meet the energy requirement of some bodyprocesses:

Acetic acid + 2 ATP Acetyl coenzyme ATCAcycle 10 mol ATP + CO + H O2 2

Propionic acid Propionyl coA + 2CO Methylmalonyl coA Succinyl coA

18 mol ATP + CO + H O2 2

TCAcycle

Butyric acid Butyryl coA Acetyl coATCAcycle 27 mol ATP + CO + H O2 2


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NFEFIBRE

COMPONENTS

NFE FIBRECOMPONENTS

VFA

MICROBIALCARBOHYDRATE

NFE FIBRECOMPONENTS

SIMPLESUGAR

NFEFIBRE

COMPONENTSVFA

MICROBIALCARBOHYDRATE

Undigested

NFE

Undigested

FIBREMICROBIAL

CARBOHYDRATE

Feed

Ru-men

SmallIntes-tine

LargeIntes-tine

Feces

VFASIMPLESUGAR

VFASIMPLESUGAR

ENERGYFAT

PROTEIN

GLYCOGEN

ENERGYFAT

PROTEIN

GLYCOGEN

Blood

Liver

Tissue

SchematicRepresentation

ofCarbohydrateMetabolism inRuminant

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Lipids Metabolism

Digestion

The ingested lipids react with bile salts in small intestine, and then aredigested by pancreatic lipase digest. The bile salts decrease the surface

tension of the ingested lipids mass [ as a chyme], this causes an emulsificationof fatty materials. The pancreatic lipase then forms emulsion from lipidsparticle, this may significantly result in increased surface area of the water

insoluble material. And this materials are more reactively to pancreatic lipase.

Pancreatic lipase are secreted in an inactive form in the lumen of smallintestine. The presence of Ca2+ may activate the pancreatic lipase. Thisenzyme is very reactive to emulsified substrates. The main action of this

enzyme is on an ester group of hydroxyl [in the position of 1 and 3 of glycerol].The end product of pancreatic lipase action in small intestine is 1,2-

diglycerides.


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Rumen microbes hydrolyze triglycerides and some lipids. Generally, lipid fromplants could be hydrolized completely compared to lipid and glycerol fromanimal origin. The product of lipid hydrolyzation is triglycerides, then arefermented to be propionic acid by rumen microbes.

In most lipids of plant, unsaturated fatty acids have cisconfiguration, but mostfatty acids of ruminant body have transconfiguration. This fact showed thatthe fermentation of ingested lipids in rumen produces some fatty acids withconfiguration of trans-isomer.

When ruminants are fed on free fat diet then the fatty acids of C14, C15, C16and C18 will be synthesized in the rumen. Fatty acids in the body of ruminants

could be synthesized from ingested carbohydrate, protein and lipid. And themost interesting thing, methionine could stimulate the synthesis of LCFA fromglucose and acetic acid.

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Schematic Representation of lipid digestion, absorption, and resynthesis. The


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Schematic Representation of lipid digestion, absorption, and resynthesis. The

heavy arrows indicate the more important pathway [Pond et. al. 1995]


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Pancreatic lipase

Triglyceride

2-monoglyceride

1,2-diglyceride


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(C13:3) Linoleic acid;Cis 9, Cis 12; Cis 15

Conjugated dienoic acid;Cis 9, Cis 11

Hydrogenation isomerase[+ H ]2+

Hydrogenation [+ H ]2+

Vaksenic acid; Cis 11

(C18:0) Stearic acid

(C18:2) Lenoleic acid;Cis 9, Cis 12

Isomeration

(C18:1) Oleic acid;Cis 9

The hydrogenation of linoleic acid in the rumen could be postulated:

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Schematic diagram of major conversions that occur in transport lipids


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g j p p

accross the intestinal mucosal cell during absorption [Pond et al., 1995]

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Ab ti f i t d li id


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Absorption of ingested lipids

Some absorptions occurs along the intestinal tract from distal [lower]duodenum to distal ileum, but main site of lipids absorption is theproximal [upper] jejunum.

Glycerol and SCFA [C2 C10] are absorbed by passive transport intomesentric blood and pass to the portal blood system.Monoglycerides and LCFA enter the brush border [microvilli] and theapical core of the absorptive intestinal mucosal cells by diffusion.Most of phospholipids in the intestinal lumen are hydrolyzed partially by

pancreatic and intestinal lipases to yield FFA.Free cholesterol is absorbed readily, but other dietary sterols exceptvitamin D are absorbed poorly.Cholesterol esters must be hydrolyzed by pancreatic and intestinal

lipases to form free cholesterol for absorption.


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After entering the epithelial cell, LCFA are converted to derivatives of coenzymeA in the presence of ATP. This fatty acid-coenzyme A complex [fatty acylcoenzyme A] reacts with monoglycerides within cell to form di and then

triglycerides.The triglycerides thus fromed contain only FA of C12 or greater chain lengthbecause shorter chain FA are absorbed directly into portal system.Before leaving the mucosal cell, the mixed lipid droplets become coated with a

thin layer of protein absorbed to the surface.These protein coated lipid droplets are called chylomicrons and consist mainly oftriglycerides with small quantities of phospholipids, cholesterol esters, and

protein.The chylomicrons leave the mucosal cell by reverse pinocytosis and enter the

lacteals via intercelluler spaces.Lacteal lead to the lymphatic system, which carries the chylomicrons to theblood via the thoracic duct.Although mammals absorb most of these LCFA into the lymphatic system, the

chicken apparently absorbs its dietary lipids into the portal blood, which carries

them dierctly to the liver. Nevertheless, the processof reesterification of FA totriglycerides in the mucosal cell is similar in birds and mammals.

F id b b d i i i i hi b h


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Fatty acids are absorbed via active transportation within rumen because thereis a gradation of energy concentration between fatty acid in the rumen and in

the blood circulation.This fact showed that each two molecules of absorbed fatty acid may loss onemolecule of CO2 and forming one molecule of bicarbonate (HCO3).After the absorption of VFA from rumen wall:

The concentration of -hydroxy butyric acid in blood vena is higher than in

blood artery, because butyric acid is oxidised to -hydroxy butyric acid;The cells of rumen wall do not convert acetic acid;The propionic acid do not change significantly.

The fatty acids in blood circulation become precursor for LCFA, and along with

glycerol forming milk or body fat.

Some factors affecting the synthesis of milk fat:The ration of acetate : propionat, the more higher this ratio value more higherthe synthesis of milk fat,The more lower rumen pH [to normal limit] more higher the synthesis milk fat;

The -hydroxy butyric acid become precursor of milk fat, because 8-10% of -

hydroxy butyric acid supplies the carbon skeleton of milk fat;The more higher glucogenic precursor [glucose] more higher milk fat, but theprecursor of non glucogenic decreases LCFA.

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Mobilization and Deposition of Fat


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Mobilization and Deposition of Fat

The Free fatty acid [non esterified fatty acid] is transported as a complex with

albumin.Chylomicrons are removed rapidly toward liver, fat storage, and other tissues.The body tissues store triglycerides, the adipose tissue is an important fat

storage.

The adipose tissues have capability in synthesis and mobilisation of fat from

carbohydrate source and oxidized fatty acid. The synthesis and mobilisation oftriglicerides in adipose tissue occur continuously, because triglyceride storageis readily as the energy source.

When the energy intake exceeds the requirement, triglycerides will be stored, andvice versa.

The triglyceride storage tends to be specifically according to the animal species.In non ruminants, the feed lipids reflects on the fat storage.In ruminants, the fat storage in body is less sensitive to the the feed lipids

because of lipid metabolism in the rumen, though there is a little effect of feed

lipids on body fat storage.

When the action of rumen microbes is inhibited, the body fat storage is influencedby the feed lipids.

The protection of feed lipid may inhibit the action of rumen microbes.


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The body fat storage of ruminant could be manipulated by adding morereadily available carbohydrate.

Normally, the body fat storage in ruminants is characterized by odd andbranhced carbon chain as the ruminal VFA derivatives.Also the body fat storage in ruminants is characterized by configuration oftrans isomer as the results of metabolism of feed unsaturated fatty acid.The fat body of ruminants apparently on a dynamic of metabolic status. The

turnover rate of triglyceride is very rapidly in the storage of ruminant body.The lipid metabolism of adult ruminants is apparently different to nonruminant:

Feed lipid [triglycerides, phospholipids, and galactolipids] is degraded bythe rumen microbes, and the occurence of microbial lipid synthesis.The hydrogenation of fatty acid, the unsaturated fatty acid is saturated to

saturated fatty acid.Lysolecithin did not act as micell membrane formation, and

monoglycerides do not act as stabilizator in micell formation.The resynthesis of triglycerides in epithelial intestine uses the pathway of

-glyceroacetic, and does not use the monoglycerides pathway.

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Protein Metabolism


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Protein Metabolism

Digestion

Digestion of ingested protein or hydrolysis of peptide bonds begins in stomach

with the presence of acidic condition [pH 2-3], it is an optimum pH for pepsinproteolytic.

The product of pepsin digestion, oligopeptides and polypeptides, then react withpancreatic proteases, trypsin, chymotripsin, and carboxypeptidase. Theproduct of these protease digestions are free amino acid and oligopeptides.

In young ruminants, rennin of stomach coagulates ingested casein rapidly.

In adult ruminants, ingested protein consist of pure protein and non proteinnitrogen. The protein that are bypassed from reticulo rumen fermentationthen will be degraded in the small intestine [just like in the monogastric].


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In adult ruminants, amino acid is hydrolyzed for : a] synthesis of protein

microbes, or b] deamination to form organic acids, ammonia and CO2. Theammonia then is combined with keto acids to form new amino acids forsynthesis of protein microbes, and are absorbed to protal circulation liver

urea.

Most of urea are filtered by kidney and then are excreted via urine. A part ofurea may be recycled to rumen via saliva or passthrough the rumen wall [via

blood circulation].

In rumen, urea is converted to ammonia and CO2 by the action of urease. In

the synthesis of protein non nitrogen, rumen microbes need a large amount oforganic acids that are originated from ingested starch.

Ingested protein that enters to abomasum [true stomach] : bypassed proteinfrom reticulorumen degradation, protein saliva from degestion process,

microbe protein, amino acids originated from resynthesis of deamination.

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Mode of Nitrogen Transaction in the


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Mode of Nitrogen Transaction in theRumen. The ovals delinetae themicrobial cell wall and numbers

adjacent to arrows refer to individualpathways as follows: 1 proteolysis bybacterial, protozoal and fungalproteases; 2 carrier-mediated peptideuptake across microbial cell walls; 3peptidolysis; 4 amination/demination; 5

protein synthesis; 6 microbialassimilation/excretion or equilibration ofamino acids and ammonia; 7 proteinnot hydrolyzed before efflux fromrumen [UDP]; 8 microbial protein efflux;9 efflux of extracellular peptides andamino acids; 10 efflux of extracellularammonia; 11 absorption of ammoniathrough rumen wall; 12 movement ofendogenous urea through the rumenwall; 13 N compounds excreted byliving cells and debris of lysed cells; 14engulfment of proteinaceous particle by

protozoa [from: Nolan, 1993]

The digestion of ingested protein in small intestine is mainly by the action of


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The digestion of ingested protein in small intestine is mainly by the action ofpancreatic proteases, i.e. trypsinogen, chymotrypsinogen, and

procarboxypeptidase]. Upon a proteolitic cleveage, these pancreatic pro-proteases are then activated.

Trypsinogen is activated by trypsin itself or by enterokinase that is secretedfrom small intestine mucose.

Activation of trypsinogen consist of transfer of simple hydrolytic on one

hexapeptide, Val-Asp4-Lys, from end terminal of amine group.The conversion of chymotripsinogen to chymotripsin occurs in three different

steps.

The combination of these pancreatic proteases degrade protein molecule to

free amino acids and small amount of peptides. As in carbohydrate

digestion, the hydrolysis is ended by hydrolase action from mucose ofsmall intestine.

Some hydrolysis action occur in the lumen of small intestine, but most ofhydrolysis occur as peptides enter and contact to brush border epithel or in

mucose cells.

Leucine aminopeptidase, a non-specific exopeptidase, is responsible for mostof the peptidase activities. Though some peptidases remain to beelucidated for their roles in the end of digestion process.

Absorption


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Absorption

The intact protein or small chain of polypeptides is unable to be absrobed bysmall intestine of adult animal.The absorption of free amino acids occur in the small intestine using an activetransportation system.

The rate of absorption depends on type of amino acid, though there is no spesific

transportation system for each type of amino acid, there is a commontransportation system. The absorbed amino acids from small intestine then enterportal vena, thus they are preceded a process in the liver to be available for body

tissue metabolism.

The absorption of amino acid by an active transportation system. The amino

acids that enter membrane cell of small intestine move againts gradient ofconcentration, this uses energy from cellular metabolism. L-amino acids are moreabsorbable than D-amino acid. Each neutral amino acid may compete for eachtransportation. For example, a high amount of leucine in the diet may increase

the need of isoleucine.


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Removing a carboxyl group by forming an ester, removing the electric chargeof amino group with acetylation, or introducing the electric charge on side chainof some amino acids may destroy the system of active transport. This caused

by a high natural specifity of the carrier system.

The basic amino acids, ornithine, arginine, and lysine have a similartransportation system along with cystine.

Arginine, cystine and ornithine inhibit the transportation of lysine.Some neutral amino acids inhibit the transportation system of some basic

amino acids. For example, methionine inhibits the transportation of lysine.

The basic amino acids is unable to inhibit the transportation of neutral amino

acids apparently. Proline and hydroxyproline have a simlar transportationsystem to sarcosine and betaine, and have a high affinity for the transportation

of neutral amino acid.

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Schematic Representation of Nitrogen Metabolism in Ruminant


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PROTEIN

MICROBIALPROTEIN

Feed

Ru-

men,Reti-culum

SmallIntes-tine

UREA Saliva

Liver

Tissue

N P N

N P NPROTEIN

AMINO ACIDS

AMMONIAPROTEIN

AMMONIA

AMINO ACIDS

Aboma-sum,

PROTEIN+METABOLIC FECAL PROTEIN

Feces

UREA

AMMONIAAMINOACIDS

UREA

AMMONIA

AMINO ACIDS

Urine

Blood

UREA+ENDOGENOUS N

TISSUE METABOLISMjachm

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The dynamic equilibrium theory of body proteins


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DietaryProtein

Aminoacids

Amino acids pool

in cells andbody fluids

Carbon chain metabolismand urea excretion

Synthesis ofnitrogen non protein

Tissueprotein

Digestion

Absorption Deamination

y q y y p

Relationship between ingested proteins and tissue proteins. Amino acids from both

sources form a common metabolic pool which can provide amino acids forresynthesis of proteins or which can be metabolized to other end products.


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References cited:

Forbes, J.M. and J. France [eds.]. 1993. Quantitatice Aspetcs of RuminantDigestion and Metabolism. CAB international, the University press, Cambridge.

Pond, W.G., D.C. Church, and K.R. Pond. 1995. Basic Animal Nutrition andFeeding. John Wiley & Sons. New York.

Preston, T.R. And R.A. Leng. 1987.Matching Ruminant Production Systemswith Available Resources in the Tropics and Sub-Tropics. Preambul Books,Armidale.

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