429: PROTEIN

NUTRITIONDanielle Pogge

PROTEIN Chain of amino acids with a specific function

Folding of protein determines function Enzymes, hormones, structural, etc

Amino acids (20) Molecules containing an amine group

Essential vs. non-essential Essential = required in the diet

Lysine = 1st limiting AA; Methionine

Protein expressed as crude protein (CP) = 6.25 x % N

Ex: DDGS, 29% CP = 4.6% N

PROTEIN IN THE BODY Specific uses in the body:

Maintenance = primary goal Growth Lactation Pregnancy (number of lambs) Wool Hormones and enzymesAntibodies

PROTEIN REQUIREMENT Ruminant Protein:

N containing feeds, NPN, endogenous Ammonia for microbes Amino acids for animals (SI absorption)

Dependent on: Stage of production

Growth, gestation, lactation Level of production

High vs. low producing Composition of gain

Lean gain vs. fat

Ewes = 9-15% (Highest = Lactation) Lambs = 11-20% (Highest = creep feeding)

Decrease with age

FACTORS INFLUENCING RUMEN PROTEIN DEGRADATION

Physical barriers Plant cell walls, cross linking of peptide chains

Feed intake Rate of passage (ingestion to excretion = ~48 h)

Fast = less degradation = more by-pass Rumen pH

Predation of bacteria Protozoa = engulf bacteria

Feed processing Heat damage (increase by-pass/decrease solubility)

Maillard Reaction SBM, DDGS, Blood Meal

Chemical damage (formaldehydes, tannins) Coating (lipid)

TYPES OF PROTEIN: 3 “Types” of protein:

Degraded Intake Protein (DIP) Metabolized by microbes in rumen

Microbial Crude Protein (MCP) Microbes themselves

Bacteria = ~50% Protozoa = 20-60%

Contribute ammonia from protein metabolismUndegraded Intake Protein (UIP)

“By-pass protein” Absorbed in the small intestine

Fate of proteins in a ruminant: Feed proteins Peptides Amino acids (rumen)

Undegraded, escaped AA, “by-pass” proteins (SI)

PROTEIN IN FEEDS:

Quality of protein is determined by the compatibility of AA profile to animals needs

New NRC (Nutrient Requirement Council) Protein requirement based off % UIP More UIP = lower total protein requirement

Ingredient % CP %UIP Corn 7.5 40Alfalfa Hay 14-22 15SBM 43 40DDGS 27 62Blood Meal 83.7 80Urea 287 0

NON PROTEIN NITROGEN Non-protein nitrogen (NPN)

N not associated with protein Free AA, nucleic acids, amines,

ammonia, nitrates, nitrites, urea Ex: Urea (287% CP)

100% degradable in the rumen Providing N for microbes

Feeding NPN: If inadequate DIP available for

microbes Precautions:

Less than 1/3 of total protein intake Requires fermentable energy Increases the S requirement

Church, 1988

SUPPLEMENTING NPN

DIP = 8-13% Total Digestible Nutrients (TDN) Below = benefit from NPN Over = excrete Ex: 100 lbs SBM = 49 lbs CP, 30 lbs DIP (49 lbs *.65

%DIP) 30 lbs DIP/87 lbs TDN = 34% of TDN

% DIP

% TDN

% CP %BCP %DIP of TDN

SBM 65 87 49 11.3 34Dry Corn 45 90 9.8 11.7 4.9*Alfalfa Hay 82 60 17 7.8 23Corn Stalks 68 55 6.3 7.15 7.78*DDGS 40 85 30 11.05 14.1Brome Pasture 80 74 21 9.62 22.7

MICROBIAL CRUDE PROTEIN (MCP) Microbial sources of N:

Diet protein NPN Recycled N

Microbial synthesis: Dependent on ammonia and amino

acids Energy

Balance available ammonia for bacterial growth

% of microbial protein entering SI: Low protein diet = ~60% High protein diet = ~40% NPN = 100%

Church, 1988

MICROBIAL CRUDE PROTEIN (MCP)

Microbial protein yield = 0.13 lbs MCP/lb TDNMP yield = TDN x 0.13

Microbial protein: ~80% protein, with digestibility of ~80% in SI

Nutritive value of microbial protein: Increases value of low quality feed Decreases value of high quality feed Can survive on NPN and low amounts of

recycled N

NITROGEN RECYCLING

Routes: saliva, across rumen wall, low rumen pH

Dependent on protein in diet Low CP = increase recycling

End of lactation dry diet = important!

Intake Protein

Protein Ammonia

Urea

NPN

Microbial Protein

Metabolizable Protein

PROTEIN ABSORPTION Metabolizable protein = available

for metabolism Absorbed amino acids Microbial protein (digestible) Undegraded protein (by-pass,

digestible)

Absorption Active transport: Intestines Portal

blood Cells Na dependent Exchangers

Amino acid availability for host: Quality, quantity, and degradation

Undegraded protein and microbial protein

PROTEIN IN THE BODY:

Church, 1988

PROTEIN NUTRITION High producing animals may need a

greater percent of escape/bypass protein Ex. Ewes with triplets

Lactation (maximize production) High quality alfalfa + corn for energy

Nutrient use: Low quality forage (corn stalks/straw)

Supplement protein High quality forage (alfalfa)

Often meets requirements = rarely supplement protein

MANAGING EWES Management practices:

Test hays for CP values Supplement on low quality forages (crop

residue) Sort ewes by production level

Lactation = greatest need (lose weight 2-6 weeks of lactation)

Cheap protein sources: Soybean meal (46.5% CP)

$310 = $0.33/lb CP DDGS (29% CP)

$200 = $0.34 Alfalfa Hay (17% CP)

$200 = $0.58

.37 .52 .66 .83 .83 .93 .93 1.10012345678

Protein intake

Milk

Yield

1.28 TDN1.86 TDN

2.35 TDN

MILK YIELD, PROTEIN, ENERGY

PROTEIN NUTRITION Why we care:

Protein deficiencies = reduces production Longer days on feed, decreased milk yield, etc. Depresses microbe function and nutrient digestion

Protein excesses: EXPENSIVE! Increases animal’s maintenance requirement Environmental concerns

Increased N excretion and run off

Economics Question: Escape protein = expensive

Is it worth it?

SUMMARY Protein requirements:

Amino acids Microbial protein

Energy is the limiting factor for protein utilization

Protein deficiency = decreased production Milk, fertility, gain