IOWA STATE UNIVERSITYDepartment of Animal Science
Terminal Traits
IOWA STATE UNIVERSITYDepartment of Animal Science
Heterosis Review
What is Heterosis - offspring performance difference over the average performance of an offspring’s parents
Why maximize heterosis? It is FREE producers are wasting money if you do not take advantage of it.
Performance of Sire = 2.00 ADG
of Dam= 1.80 ADG
Parental Average = 1.90
Offspring Average ADG = 2.10
Offspring – Parental Average = 2.10 – 1.90 = .20
Percent Heterosis = .20 /1.90 = 10.5%
IOWA STATE UNIVERSITYDepartment of Animal Science
Types of Heterosis
1. Individual Advantage of a crossbred offspring over purebred parents
2. Maternal Advantage of a crossbred mother over a purebred mother Primarily due to mothering ability
3. Paternal Advantage of a crossbred father over a purebred father Due to fathering ability? Not as important as maternal heterosis
IOWA STATE UNIVERSITYDepartment of Animal Science
Heterosis advantage for production traits (Ahlschwede et al., 1988)
ItemFirst Cross
purebred sow
Multiple cross crossbred
sow
Crossbred boar
ReproductionReproduction
Conception rate 0.0 8.0 10.0
Pigs born alive 0.5 8.0 0.0
Littersize at 21 days 9.0 23.0 0.0
Littersize weaned 10.0 24.0 0.0
IOWA STATE UNIVERSITYDepartment of Animal Science
Heterosis advantage for production traits (Ahlschwede et al., 1988)
ItemFirst Cross
purebred sowMultiple cross crossbred sow
Crossbred boar
ProductionProduction
21 – day litter weight 10.0 27.0 0.0
Days to 250 lbs. 7.5 7.0 0.0
Feed Efficiency 2.0 1.0 0.0
IOWA STATE UNIVERSITYDepartment of Animal Science
Heterosis advantage for production traits (Ahlschwede et al., 1988)
ItemFirst Cross
purebred sowMultiple cross crossbred sow
Crossbred boar
Carcass CompositionCarcass Composition
Length 0.3 0.5 0.0
Backfat -2.0 -2.0 0.0
Loin muscle area 1.0 2.0 0.0
Marbling 0.3 1.0 0.0
IOWA STATE UNIVERSITYDepartment of Animal Science
Crossbreeding Systems
Rotational crossbreeding systems Three-breed
IOWA STATE UNIVERSITYDepartment of Animal Science
Types of Crossbreeding Systems
Rototerminal
IOWA STATE UNIVERSITYDepartment of Animal Science
Crossbreeding Systems
Rotaterminal crossbreeding systems A good compromise between specific and rotational systems More heterosis realized than with rotational alone Still can save replacement breeding stock
Still must buy terminal sire Can select traits in individual breeds via the terminal sire
Can focus on strengths and weaknesses of certain breeds
IOWA STATE UNIVERSITYDepartment of Animal Science
Heterosis percentage in rotational crosses
Generation number
EquilibriumCrossbreeding System 1 2 3 4 5 6
2 breed rotation 100.0 50.0 75.0 62.5 68.9 67.2 66.7
3 breed rotation 100.0 100.0 75.0 87.5 87.5 84.4 85.7
4 breed rotation 100.0 100.0 100.0 87.5 93.8 93.8 93.3
5 breed rotation 100.0 100.0 100.0 100.0 93.8 96.9 96.8
6 breed rotation 100.0 100.0 100.0 100.0 100.0 96.9 98.4
IOWA STATE UNIVERSITYDepartment of Animal Science
Using Heterosis
Disadvantage Superior performance observed in crossbred individuals is not transmitted
upon mating Gene combinations are not transmitted to progeny
Only individual genes are transmitted to progeny Additive gene action = heritability, EPDs, EBVs
Gene combinations are rearranged or lost when crossbred animals are mated together
Random segregation of alleles during meiosis
IOWA STATE UNIVERSITYDepartment of Animal Science
Swine Production Goals
Primary goal = Maximize Profit
Genetics has a permanent effect on profit through influence or economically important production traits. Start with the best genetic merit nucleus
animals Improve their merit Use the most efficient Genetic System Provide an adequate environment for the
animals to express their genetic merit
IOWA STATE UNIVERSITYDepartment of Animal Science
Development of a Breeding Program
Identify production and carcass traits that influence profitability
Assess relative economic value of traits
Evaluate economic goals and production restrictions
Evaluate packer buying program used
Use records to evaluate current situation
IOWA STATE UNIVERSITYDepartment of Animal Science
Selection Indexes
Indexes are used for multiple trait selection
Indexes combine the traits that economically influence a selection decision
MLI = Maternal Line Index used for selection of sows and maternal line males
TSI = Terminal Sire Index
IOWA STATE UNIVERSITYDepartment of Animal Science
Terminal Sire Index (TSI)
Days to 250 Pounds (114 kg)
Backfat
Loin Muscle Area
Pounds of Lean in 185 pound (84 kg) carcass
IOWA STATE UNIVERSITYDepartment of Animal Science
Terminal Traits
Terminal traits have greatest economic impact when the commercial offspring are marketed
Traits related to Growth
Average daily gain (ADG) Average daily lean growth (ADLG) Days to market (Days) Days to some constant weight (Days to 250 lbs or 113 kg)
IOWA STATE UNIVERSITYDepartment of Animal Science
Terminal Traits
Terminal traits have greatest economic impact when the commercial offspring are marketed
Traits related to Carcass Composition
Backfat (BF) Loin muscle area or loin muscle depth (LMA or LD) Carcass lean % Fat free lean (FFL)
IOWA STATE UNIVERSITYDepartment of Animal Science
Terminal Traits
Terminal traits have greatest economic impact when the commercial offspring are marketed
Traits related to Efficiency
Feed intake (ADFI) Feed efficiency (F:G or G:F) Lean efficiency (F:LG or LG:F) Role that gain plays with feed efficiency
IOWA STATE UNIVERSITYDepartment of Animal Science
Terminal Traits
Terminal traits have greatest economic impact when the commercial offspring are marketed
Traits related to Carcass Quality
pH Drip loss Color
Minolta – Objective color scoring
Scoring – Subjective color scoring Marbling or IMF
IOWA STATE UNIVERSITYDepartment of Animal Science
Terminal Traits
Terminal traits have greatest economic impact when the commercial offspring are marketed
Traits related to Eating quality
Instron tenderness Cooking loss Consumer acceptance Sensory meat panel scores
Juiciness
Tenderness
Flavor
Off-flavor
IOWA STATE UNIVERSITYDepartment of Animal Science
Heritability Estimates
Trait Heritability Estimate Number born .10 21-d litter weight .15 Number weaned .05 Average feed intake .24 Average daily gain .30 Days to 250 lbs. .35 Feed efficiency .30 Backfat .40 Loin muscle area .45
IOWA STATE UNIVERSITYDepartment of Animal Science
Relative Economic Value of Swine Traits
IOWA STATE UNIVERSITYDepartment of Animal Science
NBS Breed Differences for ADG
bc
cdbc
ab
d
a
c cd
1.6
1.65
1.7
1.75
1.8
1.85
B CW D H L PC S Y
IOWA STATE UNIVERSITYDepartment of Animal Science
NBS Breed Differences for BF10
bccd
bbde
e
0
0.2
0.4
0.6
0.8
1
1.2
1.4
B CW D H L PC S Y
a
IOWA STATE UNIVERSITYDepartment of Animal Science
NBS Breed Differences for LMA
ee
bc bcde
cdb
4
4.5
5
5.5
6
6.5
B CW D H L PC S Y
a
IOWA STATE UNIVERSITYDepartment of Animal Science
NBS Breed Differences for pH
aa
b
db c c
5.3
5.4
5.5
5.6
5.7
5.8
5.9
B CW D H L PC S Y
e
IOWA STATE UNIVERSITYDepartment of Animal Science
NBS Breed Differences for Hunter L
cbcb
d
b
a
45
46
47
48
49
50
51
52
53
B CW D H L PC S Y
a
b
IOWA STATE UNIVERSITYDepartment of Animal Science
NBS Breed Differences for IMF
bcb
a
dc c
d
0
0.5
1
1.5
2
2.5
3
3.5
4
B CW D H L PC S Y
d
IOWA STATE UNIVERSITYDepartment of Animal Science
NBS Breed Differences for Instron
ccd
d
bb
a
5
5.25
5.5
5.75
6
6.25
6.5
B CW D H L PC S Y
bb
IOWA STATE UNIVERSITYDepartment of Animal Science
Sex Differences in NBS Progeny Test
Trait Barrow Gilt Interaction
ADG 1.81 1.67 Yes
BF10 1.20 0.98 Yes
LMA 5.34 6.00 Yes
pH 5.66 5.64 No
Hunter L 50.4 49.3 No
IMF 3.16 2.55 Yes
INST 5.63 5.94 No
IOWA STATE UNIVERSITYDepartment of Animal Science
Growth and Carcass Traits in the NGEP
Sire Line ADG (lb/d) LGOT BF10 (in.) LMABerkshire 1.85c .63c 1.25d
5.74c
Danbred HD 1.83c .72a 0.98a
6.75a
Duroc 1.95a .70ab 1.13c
6.14b
Hampshire 1.87bc .71a 1.01a
6.58a
NGT LW 1.87bc .65c 1.17cd
5.62c
NE SPF Dur. 1.97a .73a 1.11bc
6.35ab
Newsham 1.90ab .73a 0.98a
6.45a
Spotted 1.84c .63c 1.24d
5.83c
Yorkshire 1.84c .68b 1.05ab
6.17b
IOWA STATE UNIVERSITYDepartment of Animal Science
Meat Quality Traits in the NGEP
Sire Line Min. pH Drip (%) IMF(%)Berkshire 21.8a 5.91a 2.43a 2.43bc
Danbred HD 22.6b 5.75cd 3.34cd 2.61b
Duroc 22.3ab 5.85ab 2.75ab 3.19a
Hampshire 23.3c 5.70d 3.56d 2.61b
NGT LW 21.4a 5.84ab 2.92bc 2.25c
NE SPF Dur. 22.6b 5.88ab 2.81ab 3.30a
Newsham 22.2ab 5.82bc 2.99bc 2.27c
Spotted 22.9bc 5.83bc 2.88b 2.65b
Yorkshire 22.1a 5.84ab 2.85b 2.42c
IOWA STATE UNIVERSITYDepartment of Animal Science
Eating Quality Traits in the NGEP
Sire Line C. L. (%) Instr. (kg) Tend. (1-5) Moist.(%) Berkshire 22.5a 5.33a 3.50a 66.0a
Danbred HD 24.3b 5.85c 3.45ab 65.3ab
Duroc 23.1ab 5.64b 3.38ab 65.0b
Hampshire 26.0d 5.82c 3.36ab 65.0b
NGT LW 22.9ab 5.75bc 3.16c 65.5ab
NE SPF Dur. 22.5a 5.52ab 3.36ab 65.3ab
Newsham 24.2bc 5.87c 3.25bc 65.1b
Spotted 23.4ab 5.68b 3.16c 65.5ab
Yorkshire 23.5bc 5.87c 3.26bc 65.3ab
IOWA STATE UNIVERSITYDepartment of Animal Science
NGEP Terminal Line Results -- Ranked on % Lean
%Lean Min pH IMF Inst.Danbred HD 52.0 23.0 5.75 2.33 5.81Newsham 51.3 22.7 5.82 2.25 6.12Hampshire 51.2 25.3 5.70 2.57 5.86Yorkshire 49.9 23.0 5.84 2.33 6.13NE SPF Dur. 49.8 23.1 5.88 2.71 5.78Duroc 49.0 23.2 5.85 3.03 5.65NGT LW 47.7 23.4 5.84 2.15 6.09Spotted 47.4 23.3 5.83 2.35 5.92Berkshire 47.0 22.6 5.91 2.41 5.74
IOWA STATE UNIVERSITYDepartment of Animal Science
Heritabilities and Genetic Correlations on the NGEP
BF10 LMA MIN pH IMF C.L. INST BF10 .46LMA -.61 .48Minolta .08 .02 .25Ult. PH .03 -.11 -.49 .38IMF .30 -.25 .11 0.0 .47Cook. Loss .01 .01 .26 -.45 -.02 .08Instron -.17 .15 .18 -.42 -.17 .58 .20
Heritabilities on diagonal and geneticcorrelations below diagonal
IOWA STATE UNIVERSITYDepartment of Animal Science
Heritabilities and Genetic Correlations for Selected Traits in the NGEP
ADFI DAYS BF10 LMA pH IMF MIN WHC
ADFI .50
DAYS -.50 .57
BF10 .13 -.05 .46
LMA -.13 .05 -.61 .48
PH -.05 .10 .03 -.11 .38
IMF .01 -.09 .30 -.25 .00 .47
MIN .06 -.11 .08 .02 -.49 .11 .25
WHC .06 -.06 -.05 .13 -.92 -.02 .52 .19
Heritabilities on diagonal and genetic correlations below diagonal
IOWA STATE UNIVERSITYDepartment of Animal Science
Heritabilities and Genetic Correlations for Production Traits Estimated from NGEP Data
Ave. Daily Feed Intake .50
Ave. Daily Gain-SEW .19 .43
Days/250 -.50 -.60 .57
Ave. Daily Gain .58 .31 -.90 .50
Lean Gain Per Day .29 .33 -.62 .61 .48
Soundness .10 .18 -.14 .09 .07 .19
ADGADG
ADFIADFI SEWSEW D250D250 ADGADG LNGNLNGN SOUN.SOUN.
Heritabilities on diagonal and genetic correlations below diagonal.Heritabilities on diagonal and genetic correlations below diagonal.
IOWA STATE UNIVERSITYDepartment of Animal Science
“Quality” Indicators
Color
Marbling
Firmness
Water holding capacity
pH
Tenderness
Taste
IOWA STATE UNIVERSITYDepartment of Animal Science
Measurement of Color
Minolta Chromameter Minolta (range of 17-33) Hunter L (range of 40-60)
New NPPC Color Standards (1-6)
1 2 3
4 5 6
IOWA STATE UNIVERSITYDepartment of Animal Science
Color Scores
1 2 3
4 5 6
IOWA STATE UNIVERSITYDepartment of Animal Science
Water Holding Capacity
Kauffman filter paper method
Measures amount of moisture on the cut loin surface
Low numbers indicate less moisture loss
Visual Firmness/Wetness Scores (Very Firm, Firm, Soft)
Drip loss -- measures purge
IOWA STATE UNIVERSITYDepartment of Animal Science
Ultimate pH
Measured 24 hours after
slaughter
Insert pH probe into the muscle
Higher pH = darker color, low drip loss, more firmness, increased tenderness
Predictor of water holding capacity
45 minute pH is indication of PSE
IOWA STATE UNIVERSITYDepartment of Animal Science
Intramuscular Fat (IMF)
Marbling or lipid content
Laboratory analysis
Minimum amount is necessary for desirable eating quality (2.0 - 2.5%)
New NPPC Marbling Standards (1-10)
Standards correspond to intramuscular lipid content
IOWA STATE UNIVERSITYDepartment of Animal Science
Marbling Scores
1 2 3 4
5 6 10
IOWA STATE UNIVERSITYDepartment of Animal Science
Tenderness
Instron tenderness using
star probe
Measures pressure to compress cooked sample
Less pressure = more tender
IOWA STATE UNIVERSITYDepartment of Animal Science
Sensory Panel Scores
Trained sensory panel
Evaluation of palatability Tenderness Juiciness Chewiness Flavor
IOWA STATE UNIVERSITYDepartment of Animal Science
Objectives of the Study:
An evaluation of pH and hydrogen ion concentration (H+) was conducted to determine if the mathematical conversion of H+ to pH could affect 1. prediction of genetic merit of animals when pH or H+ is used as an indicator in the assessment of pork quality.
IOWA STATE UNIVERSITYDepartment of Animal Science
Introduction
Use of pH is becoming widely accepted as an indicator of pork quality.
Meat scientists and geneticists are focusing on pork quality traits and their indicators in an attempt to improve the quality of commercially produced pork.
Pork harvesting and processing industries are concerned with identifying environmental factors that can improve pork quality and its indicator traits so that more of their products can be sold as premiums products at the market place.
IOWA STATE UNIVERSITYDepartment of Animal Science
Definition of pH
pH = - log base 10 * Hydrogen Ion Concentration (Zubay, 1988).
This transformation was made not to normalize the distribution, but to reduce the size of the decimal evaluated.
The transformation can present a potential problem.
IOWA STATE UNIVERSITYDepartment of Animal Science
Table 1. An example of two sires with three progeny and each having identical pH averages, but differing hydrogen ion concentration.1
Progeny phenotypic pH
valuesAverage pH
ValueMean Hydrogen Ion
Concentration
-log 10 (mean H+), (pH
units) Sire A 5.6, 6.2, 6.2 6.00 1.2579E-06 5.90
Sire B 5.7, 6.0, 6.3 6.00 1.1655E-06 5.93
1Mean hydrogen ion concentration values have been converted to pH values (taking the negative log base 10 of the original value) in order to compare them on the same scale.
IOWA STATE UNIVERSITYDepartment of Animal Science
Procedures
Data from the National Barrow Show™ (George A. Hormel Company, Austin, MN) Purebred Progeny Test was utilized
Complete three-generation pedigrees, fixed and random classifications used for analyses, and pertinent muscle quality data were obtained from the
National Pork Board (Des Moines, IA)
Existing carcass longissimus pH data was converted to its original hydrogen ion concentration
» H+ = 10-pH
IOWA STATE UNIVERSITYDepartment of Animal Science
Procedures cont’
Hydrogen ion concentration and pH genetic predictions and heritabilities were estimated using the ASREML software (Gilmour et al., 2001)
A sire model with the full relationship matrix was incorporated
IOWA STATE UNIVERSITYDepartment of Animal Science
Heritability estimates (± SE), genetic gain estimations, and breeding value correlations of pork carcass longissimus pH and hydrogen ion concentrations from the National Barrow Show™ Progeny Test.
Trait H2 ± SE
Overall mean1Correlation of BLUP
breeding values2
pH 0.52 ± 0.074 5.681(20.84 * 10-7)
-0.92 (-0.85)
Hydrogen ion concentration
0.62 ± 0.078 23.36 * 10-7
(5.631)
1pH and Hydrogen ion concentration means have been converted to their corresponding values and are presented in parenthesis.
2Values are Pearson correlation coefficient and (Spearman rank correlation coefficient).
IOWA STATE UNIVERSITYDepartment of Animal Science
Residual distribution of pork carcass longissimus pH and hydrogen measures from the National Barrow Show ™Progeny Test
0
200
400
600
800
1000
1200
1400
Nu
mb
er
of
Ob
se
rva
tio
ns
<=5.0
9
5.2
0-5
.29
5.4
0-5
.49
5.6
-5.6
9
5.8
0-5
.89
6.0
0-6
.09
6.2
0-6
.29
6.4
0-6
.49
6.6
0-6
.69
6.8
0-6
.89
7.0
0-7
.09
pH Residual Distribution
0200
400600800
100012001400
Nu
mb
er
of
Ob
se
rva
tio
ns
<=
4.9
2
9.9
3 - 1
4.9
2
19
.98
- 24
.97
29
.98
- 34
.97
39
.98
- 44
.97
49
.98
- 54
.97
59
.98
- 64
.97
69
.98
- 74
.97
77
.98
- 84
.97
89
.98
- 94
.97
99
.98
- 10
4.9
7
Hydrogen Ion Concentration Residual Distribution
IOWA STATE UNIVERSITYDepartment of Animal Science
Discussion of results
Both heritability estimates would be considered relatively high
Greater genetic progress would be expected if selection were based on H+ concentration rather than pH
The Pearson correlation ( -0.92) between the pH and H+ concentration breeding values was expected
IOWA STATE UNIVERSITYDepartment of Animal Science
Discussion of results cont’
Spearman rank correlation between the breeding values for pH and H+ concentration was -0.85
While relatively strong, the rank correlation does indicate that some difference in ranking of sires is likely to occur depending whether they are ranked based on pH or H+ concentration breeding values
IOWA STATE UNIVERSITYDepartment of Animal Science
Example truncation selection for pH and Hydrogen ion concentration based on top 5 percent breeding values.
IOWA STATE UNIVERSITYDepartment of Animal Science
Example truncation selection for pH and Hydrogen ion concentration based on top 1, 5, and 25% percent breeding values.
H+ Selection differential
SelectionIntensity
Select on pHSelect on H+
SelectionDifferential
Selectiondifferential loss, %
25% -0.78 -0.82 -0.04 4.8
5% -1.80 -1.93 -0.13 6.7
1% -2.53 -2.91 -0.38 13.1