Danielle Pogge

Chain of amino acids with a specific function



Amino acids (20)


Folding of protein determines function
Enzymes, hormones, structural, etc
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
 Specific







uses in the body:
Maintenance = primary goal
Growth
Lactation
Pregnancy (number of lambs)
Wool
Hormones and enzymes
Antibodies

Ruminant Protein:

N containing feeds, NPN, endogenous



Ammonia for microbes
Amino acids for animals (SI absorption)
Dependent on:

Stage of production


Level of production


Growth, gestation, lactation
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

Physical barriers


Plant cell walls, cross linking of peptide chains
Feed intake

Rate of passage (ingestion to excretion = ~48 h)



Rumen pH
Predation of bacteria


Fast = less degradation = more by-pass
Protozoa = engulf bacteria
Feed processing

Heat damage (increase by-pass/decrease solubility)



Maillard Reaction
 SBM, DDGS, Blood Meal
Chemical damage (formaldehydes, tannins)
Coating (lipid)
3

“Types” of protein:
Degraded Intake Protein (DIP)


Microbial Crude Protein (MCP)



Metabolized by microbes in rumen
Microbes themselves
 Bacteria = ~50%
 Protozoa = 20-60%
Contribute ammonia from protein metabolism
Undegraded 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)
Ingredient
% CP
%UIP
7.5
40
14-22
15
SBM
43
40
DDGS
27
62
Blood Meal
83.7
80
Urea
287
0
Corn
Alfalfa Hay

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


Non-protein nitrogen (NPN)

N not associated with protein


Ex: Urea (287% CP)



Free AA, nucleic acids, amines,
ammonia, nitrates, nitrites, urea
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
% DIP
% TDN
% CP
%BCP
%DIP of TDN
SBM
65
87
49
11.3
34
Dry Corn
45
90
9.8
11.7
4.9*
Alfalfa Hay
82
60
17
7.8
23
Corn Stalks
68
55
6.3
7.15
7.78*
DDGS
40
85
30
11.05
14.1
Brome Pasture
80
74
21
9.62
22.7
 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

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

MP yield = TDN x 0.13

Microbial protein: ~80% protein, with digestibility of
~80% in SI
 Nutritive



protein yield = 0.13 lbs MCP/lb TDN
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
Intake Protein
NPN
Metabolizable
Protein
Protein
Ammonia
Microbial
Protein
Urea
 Routes:
saliva, across rumen wall, low rumen pH
 Dependent on protein in diet

Low CP = increase recycling

End of lactation dry diet = important!

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
Church, 1988
 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
 Management



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

$310 = $0.33/lb CP
DDGS (29% CP)


protein sources:
Soybean meal (46.5% CP)


practices:
$200 = $0.34
Alfalfa Hay (17% CP)

$200 = $0.58
M
i
l
k
Y
i
e
l
d
8
2.35 TDN
7
1.28 TDN
6
1.86 TDN
5
4
3
2
1
0
.37
.52
.66
.83
.83
.93
Protein intake
.93 1.10
 Why

Protein deficiencies = reduces production



Longer days on feed, decreased milk yield, etc.
Depresses microbe function and nutrient digestion
Protein excesses:




we care:
EXPENSIVE!
Increases animal’s maintenance requirement
Environmental concerns
 Increased N excretion and run off
Economics Question:

Escape protein = expensive
 Is it worth it?
 Protein


requirements:
Amino acids
Microbial protein
 Energy
is the limiting factor for protein
utilization
 Protein

deficiency = decreased production
Milk, fertility, gain