Animal Science 233 Applied Animal Nutrition

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Animal Science 233Applied Animal Nutrition

• Protein Systems

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Protein Terminology

• Bioavailability the degree to which an ingested
  nutrient is absorbed in a form that can be
  utilized
• Includes
• Digestion
• Absorption
• Utilization

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Protein Terminology

• True protein protein composed only of AA
• Nonprotein nitrogen (NPN) compounds that contain
  N and can be converted to protein by bacterial
  action by RUMINANTS
• e.g. urea

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Protein Terminology

• Crude protein (total protein) protein composed
  of true protein and any other N compounds
• Rememberdetermined by Kjehdahl
• CP N 6.25
• Feed contains 7 N so has 7 6.25 43.75
  CP
• OK estimate if no NPN sources used

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Protein Terminology

• Digestible protein the portion of CP which the
  animal can digest
• Difference between the amount in the feed and the
  amount in the feces
• If feeding 100 g of CP from Distillers Dried
  Grains and get 15 g CP in manure, then DDG is 85
  digestible

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Protein Terminology

• Metabolizable protein Protein that is absorbed
  by the animal and utilized for growth and
  maintenance
• Protein used for function
• Digested ? Utilized

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Review of Protein Metabolism

• Animals do not have a protein requirement, but a
  nitrogen requirement in the form of amino acids.
• Ratio of Essential aas-to-Non-Essential aas
• The animal consumes proteins, which are complexes
  of amino acids in the form of folded peptides.

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Review of Protein Metabolism
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Review of Protein Metabolism

• The proteins are denatured by the stomach acids
  (HCl).
• Bonds are broken that allow the structure to
  unfold
• This unfolding is crucial in the absorption of
  the proteins

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Review of Protein Metabolism

• The unfolding of the protein allows enzymes to
  bind with active sites of the protein
• Activates the enzymes
• The enzymes can now cleave (cut) the protein into
  peptides and amino acids
• Which can be absorbed across the gut epithelium

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Review of Protein Metabolism

• Fate of absorbed amino acids
• Cells of the body incorporate the aas into
  tissue or utilize for protein synthesis
• Muscles
• Organs
• Enzymes
• Used as a fuel source after glucose levels
  decline
• Approx. 1-2 hours after a meal

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Review of Protein Metabolism

• AA imbalance
• If the ratio (essential-to-nonessential) is
  imbalanced, then aas will not be incorporated
  into tissues or used for protein synthesis and
  will be burned as energy or accumulate in the
  blood

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Review of Protein Metabolism

• AA imbalance
• Burning of aas by the liver 6 of daily
  maintenance energy
• Production of N products - Urea Cycle
• The accumulation of amino acids in the blood will
  also decrease intake
• Triggering hormones and satiety receptors
• Performance begins to drop off

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Protein Quality

• Definition balance of bioavailable AA in a feed
  ingredient relative to animals AA requirement
• Changes in protein structure will change protein
  structure and availability, not presence of N

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Protein Quality

• How is it possible to change protein structure
  and thus quality?
• Denaturation
• Loss of structure and biological activity
• Heat, UV light, acids, alkali, organic solvents

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Protein Quality

• How is it possible to change protein structure
  and thus quality?
• Maillard Reaction (Browning Reaction)
• Caused by excess heat cooking, drying, improper
  storage
• Protein-CHO complex formed
• Protein is still there, just unavailable to
  animal

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Maillard Reaction
HCO CHOH CHOH
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Maillard Reaction
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Protein Quality

• How is it possible determine protein quality?
• Biological Value (BV) measure of amount of true
  protein absorbed from the intestinal tract and
  how well the digestive system converts it into AA
• Higher for animal protein than plant protein

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Protein Quality

• How is it possible determine protein quality?
• Biological Value
• Efficiency with which a protein furnishes the
  required amounts of essential amino acids needed
  for productive body functions
• Used to index or rank protein quality
• Expressed as

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Protein Quality

• How is it possible determine protein quality?
• Biological Value
• N intake (Urinary N Fecal N)

BV
100
N intake Fecal N
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Biological Value

• Biological Value
• Egg Protein (albumin) ? Highest BV (97)
• Animal Origin 60 - 80
• Plant Origin 40 - 80
• FYI BV are indexed against albumin to rate
  protein quality
• BVs gt 70 are capable of supporting growth
• Assuming E is in adequate proportion
• Mixing low BV proteins with higher BV proteins
  may enhance the use of low BV proteins

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Protein Quality

• Other methods for determining protein quality
• Net Protein Utilization Measures the efficiency
  of growth by comparing body N content resulting
  from feeding a test protein to the body N content
  of animals consuming a protein-free diet for the
  same length of time

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Net Protein Utilization

• Advantages Large number of values can be
  obtained over short period of time
• Disadvantages Normal animal function is
  compromised
• Limited use on this type of study

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Protein Quality

• Other methods for determining protein quality
• Protein Efficiency Ratio (PER) Feeding trial in
  which protein sources are compared in terms of
  gain in body weight per gram of protein or N fed

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Monogastric Protein Systems
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Monogastric Protein Systems

• Swine poultry industries have done away with
  the crude protein system. Research in their
  respective industries have focused on amino acid
  requirements
• Most swine and poultry diet requirements were
  based on corn soybean meal diets
• Limiting AAs Lysine (1st), Methionine,
  Tryptophan

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Monogastric Protein Systems

• Limiting AA The essential amino acid that is
  present in the lowest quantity in the diet when
  expressed as a percentage of the animals amino
  acid requirement
• Lysine, Methionine, Tryptophan

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Monogastric Protein Systems

• First Limiting AA concept
• Current protein system focuses on meeting the
  animals need for lysine (or methionine in
  poultry)
• Based on Corn/Soybean meal diets
• Other amino acid requirements should be satisfied
  once the 1st limiting amino acid is met

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Monogastric Protein Systems

• Ideal AA concept Provide a perfect pattern or
  balance of essential nonessential amino acids
  in the diet without any excesses or deficiencies

Chung and Baker, 1992
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Ideal AA concept

• Basis of derivation of ratios (ideal concept)
• Growth studies
• Whole body AA profile
• Ratios differ for growth vs. maintenance

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Ideal AA concept

• Ratios for Pigs

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Ideal AA concept

• Ratios for Pigs
• Increase proportion of total AA required as
  animals increase in age
• BOTTOM LINE Different ratios at different
  ages/stages of production

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Ideal AA concept

• How do we meet those individual amino acid
  requirements?
• 1. Use complimentary protein sources
• Corn and SBM
• 2. Use crystalline amino acids
• Lysine, Methionine, etc.

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Ideal AA concept

• Advantages/Applications
• Simplifies feed formulation
• Helps in formulating for improved AA balance
• Decrease N excretion
• Improved efficiency of growth
• Improved energy efficiency
• AA used inefficiently as an energy source

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Ideal AA concept

• Producers need to concentrate on systems that
  keep excessive N excretions low, but still
  maintain low costs of gain

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Ideal AA concept

• When do crystalline forms of amino acids come
  into play?
• When it becomes economically sound to replace
  grain supplemental protein sources with
  crystalline forms
• Lysine (L-Lysine HCl)
• Methionine
• Need to monitor all other amino acid
  requirements, because limitations
  (deficiencies/imbalances) can show up depending
  on type of feed being supplied

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Digestible AA

• Swine NRC represents AA requirements on a
  digestible and total basis
• Total requirement on as is basis or total
  amount that must be there to meet needs
• Digestible amount that is digestible required
  to meet needs
• More refined basis for determining requirements

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Apparent digestibility of AA in some common swine
protein sources
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Ruminant Protein Systems
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Ruminant Protein Systems

• Rumen fermentation puts a twist on providing
  protein to the animal
• Microbial requirement
• Animal requirement
• For a long time it was thought that all protein
  leaving the rumen was of good quality adequate
  to meet the essential amino acid requirements of
  the animal

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Ruminant Protein Systems

• DIP - Degradable Intake Protein
• Degraded in the rumen
• UIP - Undegradable Intake Protein
• Escape - Not degraded in the rumen
• usually called bypass or escape protein
• 2 factors that have the largest impact on protein
  degradability
• 1. Enzyme kinetics (protease activity)
• 2. Passage rate

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Salivary Gland
Bact. Undeg Prot.
Prot.
AAs
Undig prot.
Feces
Kidneys
Bladder
Rumen
Abomasum
Urine
Liver
Bacteria
Feed Protein
Blood pool
UIP
ENERGY
Urea
NPN
NH3
True protein
Amino acids
DIP
Amino acids
NPN
Body tissue
Milk protein
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Metabolizable Protein System

• Quantity of protein digested or amino acid(s)
  absorbed in the post-ruminal portion of the
  digestive tract of ruminants
• a.k.a. apparent digestible protein in
  monogastrics
• Quantity / Quality of protein flowing out of the
  rumen
• Evaluates UIP outflow (escape value)
• Degraded dietary protein used in the synthesis of
  microbial protein (BCP)
• Both sources (UIP BCP) are considered amino
  acid sources for the animal

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Metabolizable Protein System

• Does a better job at predicting protein needs of
  cattle
• vs. CP levels where many nitrogen sources are
  unavailable to the animal
• Couples ruminal degradation of dietary protein
  with maximal protein synthesis rate of microbes
  based on dietary energy level

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Bacterial Crude Protein (BCP)

• Dead or dying microbes from the rumen
• Broken down by digestive enzymes and secretions
• Absorbed in the small intestine
• Supply 50 - 100 of the MP required by beef
  cattle, depending on UIP source
• BCP synthesis can be slowed by
• 1. High, readily-fermentable grain diets
• Due to low pH
• 2. Low quality forage diets
• Inadequate energy to sustain growth

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Ruminant Protein Systems

• Nonprotein nitrogen (NPN) compounds that contain
  N and can be converted to protein by bacterial
  action by RUMINANTS
• e.g. urea

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Non-protein Nitrogen (NPN)

• Main source UREA (also biuret, triuret)
• Used only to supply N to microbes
• Microbes have an enzyme called urease which
  breaks the molecule into primarily NH3
• Mammals do not have this enzyme
• NH3 is then incorporated into bacterial growth,
  as long as energy is sufficient
• Excess NH3 is absorbed across the rumen wall into
  the animals blood system.
• NH3 is extremely toxic to mammals

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NPN

• The liver then converts the NH3 to urea and
  releases it back into the blood
• Fate of urea
• Recycled back to the rumen
• Microbes get second chance at the nitrogen
• Via ruminal epithelium
• Via the saliva
• Excreted via urine
• Excess NH3 can result in toxic shock to the
  system
• Liver cant keep up
• Urea toxicity
• Vinegar drench

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Undegradable Intake Protein (UIP)

• Escapes microbial breakdown in the rumen
• Provides a source of unaltered amino acids to
  the animal
• Possibly greater in quality and quantity versus
  BCP
• Methods of increasing escape value of protein
  sources
• Heat treatment
• Treatment with formaldehyde or tannins
• Encapsulation of amino acids
• Use of amino acid analogs
• Control of microbial metabolism in the rumen

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High escape value does not necessarily mean
improved animal performance

• Escape (By-pass) protein may be poorly digested
  in the small intestine
• Balance of amino acids in postruminal protein may
  be out of whack
• Increased non-essential AAs
• Foul up the transport mechanisms
• Energy supply or nutrients other than amino acids
  may limit animal performance

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Ruminal Degradability of Plant Protein Sources
vs. Urea
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Animal Protein Sources

• Excellent source of essential amino acids
• Especially for non-ruminant animals
• Can not be used in Ruminant diets
• BSE
• Consumer perception
• Not palatable to animals
• Especially blood and meat meal

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Animal Protein Sources

• Indigestible components
• Keratin, bone, connective tissue
• By-products can be extremely high in certain
  minerals
• Ca, P, S

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Protein Digestion in Ruminants

• Neonatal ? 4 - 6 weeks of age
• Rumen has not developed
• Essentially a monogastric system
• Milk / Milk Replacer
• 6 weeks ? 8 weeks of age
• Functioning rumen (consuming solid foods milk)
• Need to satisfy both the rumen environment and
  the growing animal
• Natural proteins preferred
• Microbial population in not adequate to utilize
  NPN

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Protein Digestion in Ruminants

• 8 weeks
• Functioning ruminant digestive tract
• Utilize natural and NPN sources of nitrogen

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Protein Feedstuffs

• Sources and their value in rations

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Protein Feedstuffs--Roughages
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Protein Feedstuffs--Concentrates
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Protein Feedstuffs--Byproducts
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Protein FeedstuffsAnimal protein sources
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Protein FeedstuffsMisc. protein sources