Transcript Document 7190587

Mongastric Production
Swine Section
Breeding and Selection of
Swine
Eight major breeds of swine in
the U.S. today include:
Berkshire (England)
Chester White (U.S.)
Duroc (U.S.)
Hampshire (England)
Landrace (Denmark)
Poland (U.S.)
Spotted Breed or Spots (U.S.)
Yorkshire (England)
Composite swine breeds
developed by breeding Co.
PIC (Pig Improvement Co.)
Monsanto Choice Genetics
Genetipork
Babcock (www.babcockswine.com)
Danbred
What general factors determine
swine performance?
Genetics
Environment
Genetics x Environment (generally
referred to as the interaction of
genetics and environment)
What methods are used by swine
producers to select breeding stock?
1) Visual appraisal
2) Performance data
3) Pedigree
Why visual appraisal?
Type (conformation)
Soundness: feet and legs; underline
& reproduction.
Health
Behavior
What kind of performance data
is used for selection?
Sow productivity index (SPI) which
may include number of pigs born and
litter weight at weaning.
Growth rate (ADG or perhaps days to
a given weight)
Feed efficiency (F/G or G/F)
Backfat (BF)at a given weight
Loin eye area (LEA) at a given
weight
Where are pigs performance
tested?
From the late 50s until about the mid 80s boars
were often tested in Central Test Stations.
Seedstock producers have also tested their own
boars (and some gilts) on their own farm. This is
known as on-the-farm testing.
Today breeding companies collect their own
performance data on boars and gilts sold for
breeding.
Some Individual seedstock producers collect
progeny data from prospective sires via
commercial swine producers
Performance vs Progeny
Testing
Performance testing is collecting
performance data on the individual
you use in the breeding herd as the
boar or the sow.
Progeny testing is collecting
performance data on the offspring of
the boar (sometimes gilts) you plan
to use in your breeding herd.
Predicting Genetic Progress
GP = S.D. x Heritability
S.D. refers to selection differential.
Selection Differential refers to the average
reach or superiority of selected boars and
gilts.
Reach is the superiority of individuals
(boars and gilts) compared to the herd
average.
Heritability is the percent of the total
variation of a trait that is due to heredity.
Example of calculating GP
Herd average BF at 250 lbs = 1.25”
Select a boar = .70”
Select a group of gilts that average =
1.0”
Reach of the boar = -.55”
Reach of the gilts = -.25”
Average reach (S.D.) = -.40”
GP calculation continued
Assume heritability for BF = 50%
GP = -.40” x .50 = -.20”
(S.D.) x (Heritability)
Expected BF of the progeny
1.25” minus .20” = 1.05”
SD vs EBV vs EPD
EBV
EBV
EBV
EBV
EBV
EPD
= Estimated Breeding Value
= Reach x Heritability
of boar = -.55 x .50 = -.275”
of gilt = -.25 x .50 = -.125”
of boar + gilt = -.40”
= Expected Progeny Difference
SD vs EBV vs EPD continued
EPD = ½ EBV (Reach x Heritability)
EPD of boar = -.275/2 = -.1375”
EPD of gilt = -.125/2 = -.0625”
EPD of boar + EPD of gilt = -.20”
So, G.P. = EPD of boar + EPD of gilt
Comparison of terms
GP = S.D. x Heritability
EBV = Reach x Heritability
EPD = ½ EBV
GP = EPD (male) + EPD (female)
Heritability of economically
important traits
High
Med
Low
>40%
20-40%
<20%
Heritabilities of various swine
traits
Reproductive traits = low
NBA (10%)
Production traits = medium
ADG (30%) F/G (35%)
Carcass traits = high
BF (50%) LEA (50%)
How are pedigrees used for
breeding stock selection?
To avoid inbreeding
To identify productive families
To avoid genetic defects, such as
PSS, scrotal hernias, etc.
Crossbreeding Programs for
Commercial Swine Producers
Nearly all commercial hogs are
crossbred.
Which commercial hogs are not
crossbred?
Answer: purebred animals that do
not meet the selection criteria to be
marketed as breeding animals.
Why raise crossbred hogs?
To capitalize on hybrid vigor
(heterosis).
Lowly heritable traits benefit the
most from heterosis.
To combine the desirable
characteristics of different breeds.
From a practical standpoint
crossbred sows farrow more pigs,
wean more pigs and wean heavier
litters.
What is heterosis?
H.V. = the average superiority of the
crossbred offspring compared to the
parent average for a particular trait.
H.V. = ((F1-P1)/P1) x 100) where F
stands for “filial” or offspring and P
refers to the parents.
Calculating heterosis
Duroc boar from a litter of 10 pigs
Landrace sow from a litter of 12 pigs
NBA of crossbred offspring = 13
Avg litter size of parents = 11
Heterosis = (13 – 11)/11 x 100))
(F1 – P1)/P1 = 18.2%
Systems of crossbreeding
Rotational cross = generally uses
home raised replacements
Illustrate a three breed rotational
cross through several matings.
Terminal cross = all progeny are
marketed.
Illustrate how a terminal
crossbreeding system works.
What breeds should be used to
produce commercial hogs?
Research and practical experience have shown
that all breeds were not created equal.
White breeds such as Landrace, Yorkshire and
Chester White excel in sow productivity traits.
Durocs are recognized for their superiority in ADG
and F/G.
Hampshires are well known for superior carcass
traits.
Colored breeds seem to be more hardy and are
especially durable in outside systems.
Coat Color Inheritance in Pigs
Self Black (unbelted Hampshire) and Black
Spotted (Poland and Berkshire) are both
dominant to Red (Duroc).
Self White (Chester White, Landrace and
Yorkshire) is dominant over most black
and red breeds.
Self Black x Self White = commonly
produces a blue roan (white hair with
patches of dark pigmented skin). Referred
to as Blue Butts.
What breeds are used?
Actually most of today’s seedstock are
composite breeds that have been
developed by the various breeding
companies based upon a combination of
white and colored breeds.
Landrace and Yorkshires are commonly
used as maternal lines.
Durocs and Hampshires are used as
paternal lines.
Website for breeds of swine
http://www.ansi.okstate.edu/breeds/
swine