So youd like to show a

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So youd like to show a Champion
Dan Frobose Ohio State University Extension
Do you need the Stress gene to win?
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Can you tell which pig is the stress carrier?
or
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History
Is not new, 30 year history in U.S.
Can be inherited from each parent
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History
Associated with lean, heavy muscled pigs.
Sudden unexplained death.
Pale soft exudative (PSE).
Nervousness triggered by stress.
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Why was the stress gene propagated?

Stress positive pigs were 2.7 4.0 higher in
lean composition.
Increased muscle and decreased fat.
Fat was targeted as the No. 1 enemy of the Pork
Industry.
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What are the underlying causes of PSS.
Several metabolic and biological reactions.
Reduced muscle energy stores (glycogen).
Increase in lactic acid (metabolic acidois).
Muscle- lacks ability to bind calcium and break
down phosphates.
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Why do we need to get rid of the stress gene?
Smaller frame size
Lower feed intake
Lower daily gain
Smaller litters born and reared
Inferior meat quality
Higher death loss
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Stress Gene Economic Effects
Normal Heterozygote
Heterozygote Trait (NN) (Nn)
Diff Value /pig Days 250
172.8 172.7 0 Tenth Rib Backfat
1.13 1.12 0 Loin Muscle Area
5.94 6.23 .29 1.65 Ultimate
pH 5.85 5.84 0 Intra-muscular
fat 2.60 2.28 -.32
-3.17 Shear Force 5.66 6.16
.50 -2.08 Drip Loss 2.61
3.09 48 -0.31 Total
-3.91
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PSS causes/ contributing factors
Disease is precipitated by sudden muscle activity.
-stressful situation, snaring, clipping, loading,
commingling, castration, weather, estrus
The carrier pig is genetically susceptible
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What are the visual signs to look for in
susceptible pigs?
Muscle tremors
Twitching of the face
Rapid respiration
The skin becomes red and blotched
Rise in temperature
Death usually occurs within 15-20 minutes
Rigor mortis (stiffening of muscles after death
within 5 minutes)
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Genetics of PSS
No breed is free of PSS
Some breeds are high some low
Inherited in a simple reserve manner both
parents must be carriers
Nn x Nn
1 nn Positive
2 Nn Carriers
1 NN Non Carrier
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How to get rid of PSS
Select sire free of gene
DNA Test
Blood test (30)
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Standards
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Pork Quality
High quality, uncured pork is redish pink in
color, firm in texture, free of surface juices,
and contains modest amounts of marbling.
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Poor Quality Pork
Soft mushy loose textured (pale)
Muscles are acidic (low pH protein in muscle
loose ability to hold juices)
Color variation
Low marbling
Shrinkage above 7
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How can I manage PSS susceptible pigs?
Minimize excitement
Avoid crowding, electric prods, quiet
Dont co-mingle pigs
Avoid temperature extremes
Properly design facilities
Rest pigs prior to slaughter
Avoid snaring and clipping
Dont overwork pigs in show ring
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How much influence does the stress gene have in
the U.S. show pig population?
Study conducted by Dr. Jodi Sterle, Texas AM
University
Blood samples taken from 2000 and 2001 (SALE)
and (HLSR)
Obtained from champions and 1st and 2nd place pigs
193 out of 20,603 entries (less than 1)
(SALE) San Antonio Livestock Exposition (HLSR)
Huston Livestock Show and Rodeo
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Texas AM Observations
Total combined data NN 107 barrows 55.44



Nn 78 barrows 40.41 nn 8 barrows
4.15 Frequencies by breed Breed number NN N
n nn Chester White/Landrace/White OPB
18 11 7 0 Yorkshire 24 20 4 0
Hampshire 34 21 13 0 Poland
China/Spot 23 3 15 5 Berkshire 12
6 3 3 Duroc 33 17 16 0 Crossbred
49 29 20 0
NN normal, Nn heterozygous, nn homozygous
positive for the stress gene. (Sterle Texas AM
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Texas AM study observations
2000 NN 51 barrows 52.58 Nn 41
barrows 42.27 nn 5 barrows
5.15 2001 NN 57 barrows 59.37 Nn 36
barrows 37.50 nn 3 barrows 3.13
NN normal, Nn heterozygous, nn homozygous
positive for the stress gene
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Texas AM Study Carcass Contest Observations
32 top placings were eligible in the past two
years at SALE and HLSR
16 were NN 16 were Nn No placing carcass were nn
Carcasses were evaluated for loin muscle color,
muscle firmness, marbling or fat firmness
33 out of the top 198 placing were disqualified
60 of disqualifications in carcass contest
inherited at least one copy of stress gene
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MQP 2001 Quality Lean Growth Champion and
Reserve Loins
BF10 .70, LMA 7.15 Lean Gain 0.945 lb/day
Color 3, Firm 3, Wet 2 Marb 4, pH 5.70
Quality Index 6.75 Stress negative
BF10 .90, LMA 8.65 Lean Gain 1.006 lb/day
Color 4, Firm 3, Wet 3 Marb 2, pH 5.98
Quality Index 6.25 Stress negative
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PSS
The swine industry has decided to take steps to
eliminate this gene. Pork industry lenders feel
that the risk of losing customers (domestic and
export) due to poor pork quality are not worth
the benefits of increased muscle and leanness.
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NSR Policy
National Swine Registry (NSR) has implemented
No known stress positive or stress carrier
animals will be allowed to be exhibited or sold
at any NSR sponsored event.
NSR also requires the DNA stress gene status of
A.I. sires to be declared on all A.I.
certificates issued for the registration of
litters.
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Is the stress gene needed to win?
At two of the largest barrow shows in the county
and 2001 Ohio State Fair the answer is NO!
Over 55 of the top 1 at SALE and HLSR were free
of stress gene.
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Can you tell which pig is the stress carrier?
or
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Conclusion
Our Seedstock and Club pig industry has available
today the genetics to produce competitive high
quality offspring without the need of the stress
gene. When you go out to purchase your project
pigs for 2002 keep in mind that you are a very
important link in the pork quality chain. Ask
for project pigs that are free of the stress gene.