Master Goat Producer

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Understanding Genetics For Use
In Sheep and Goat Production
Adapted for ABAS 3500 by Dr. Warren
Gill Originally developed by Dr. Dennis Onks
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PHENOTYPE
AN ANIMALS VISUAL EXPRESSION OR PERFORMANCE IN
ANY TRAIT
The Phenotype is the outcome of Genetic Transfer
as developed in a production Environment
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PHENOTYPE
Defined as the sum of the genetic and
environmental variation
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Sound Breeding Program
Maximum Genetic Improvement occurs In a Herd
Environment that allows the Improved Genetics to
be Expressed
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Sources of Environmental Variation

• Weather
• Land Topography
• Structural Resources
• Forages and Feeding
• Health and Sanitation

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How Traits are Inherited
Genetic Variation is the study of

• All body cells contain Blueprints with
  instructions as to how an animal will look or act
  etc.
• DNA or Deoxyribonucleic Acid contains the genes
  of traits in the double helix ribbons located in
  every cell

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GENE
The combination of genes are attached to
chromosomes which guide the animal to express A
trait or response. AKA Genotype (p7 fig. 3 4).
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Species differ in chromosomesp5
Humans 23 pairs of chromosomes Cattle 30
pairs of chromosomes Sheep 27 pairs of
chromosomes Swine 19 pairs of chromosomes Chicken
39 pairs of chromosomes Goat 30 pairs of
chromosomes Horse 16 pairs of chromosomes
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How Traits are Inherited
The science of ½s since each living animal
receives a Sample ½ of its genetics from its
father and a sample ½ of its genetics from its
mother. The process of halving is done by Meiosis
(division p 6)
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Gene Dominance
One Gene overshadows The expression of the other
one in the pair (allele)
Were heterozygous (different)
WW and Ww White
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Recessive Genes

• The gene that is overshadowed by a dominant gene.
  Recessive genes can only be expressed when they
  both are present

Were Homozygous (the same)
RED COAT COLOR ww
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Figure 3 Spider Syndrome Genetics
¼ show symptom, ½ are carriers, ¼ are clean
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Figure 4 Rambouillet Horns Multiple alleles
sex linked
1/8 Polled Rams, 1/4 Scurred,1/8 Horns ½ Polled
Ewes
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QUALITATIVE TRAITSp8
TRAITS THAT ARE AFFECTED BY A SINGLE OR A
FEW PAIR OF GENES COAT / FLEECE COLOR (See
Epistasis p 7) TWINNING BOOROOLA
MERINO SCRAPIE RESISTANCE TEETH HORNS
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QUANTITATIVE TRAITS
TRAITS AFFECTED BY NUMEROUS PAIRS OF GENES (p
8) The thousands of genes present
make countless combinations possible in
an animal. Since genes are too small
to identify individually, they express
their presence by such outward effects
as differences in growth, carcass or
reproduction traits
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Quantitative Traits (contd)
Growth traits Birth weight Weaning
weight Yearling weight Growth rate (ADG) Frame
size Carcass traits Rib eye area Fat
thickness Marbling Reproduction
traits fertility/adaptability
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Which buck has the best genetics for growth?
Is the buck on the left bigger because he had
better genetics for growth or because he was
provided a better environment?
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IMPROVEMENT OF ANY TRAIT DEPENDS
MEASURING DIFFERENCES IN A TRAIT (Variation p 10)
ACCURATELY IDENTIFYING SUPERIOR INDIVIDUALS IN
THE TRAIT
USING SUPERIOR INDIVIDUALS AS PARENTS
HOW HERITABLE THE TRAIT IS (heritability)
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To Make Progress in Selection the trait must be

• Variable
• Heritable
• Measurable

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What is Selection?

• Choosing animals to be parents for the next
  generation to produce certain characteristics
• Low Birth weight
• Heavier Weaning Weight
• Gaining Fast
• Horned or Polled
• Temperament
• Better Eating Quality

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Heritability(h2)
Percentage of the differences (measured or
observed) in a trait between animals that are
transmitted to the offspring. P 10
Reproduction fertility,etc.
Low
Production growth
Moderate
Product carcass
High
(Heritability is a measure of how a trait will
respond to selection)
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Low Heritable Traits

• Birth Interval 5-10
• Number Born 15
• Rear Legs 15
• Udder Support 20
• Reproduction 15

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Moderately Heritable Traits

• Birth Weight 30-40
• Weaning Weight 20-30
• Yearling Weight 40
• Feed Conversion 40
• Quality Grade 40
• Ribeye Area 40-45
• Muscling 40-45

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Highly Heritable Traits

• Mature Weight 65
• Milk Fat 55
• Stature, Frame 45-50
• Carcass Weight 45-50
• Scrotal Circumference 50

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Selection for traits is Impactedby the
Correlation(r2)Between Traits p 11

• Genetic Correlation measures the genetic
  association between traits
• Phenotypic Correlation measures the local or
  environmental association between traits
• Correlation ranges in value of 1.0 to 1.0
  (indicates the direction of association)

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Phenotypic Correlations
Body WT Length Heart Girth Backfat
Loin Area
Kidding Lambing Difficulty
Length
Heart Girth
Backfat
Loin Area
Scrotal Circumference
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Use of Heritability andCorrelations

• Selection for Weight makes moderate progress
  (h240-65)
• Positive Correlation (r2.50) between birth,
  weaning and carcass traits means Selection will
  result in increases in all three traits.

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Use of Heritability andCorrelations

• Selection for Weight makes moderate progress
  (h240-65)
• Negative Correlation (r2-.50) between weight and
  Kidding/Lambing Difficulty means selection for
  more weight will result in increased birthing
  difficulty with increasing birth, weaning and
  carcass weight.

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Selection for the Industry

• Consumer
• Packer
• Feeder
• Commercial producer
• Purebred Breeder
• Each section may have differing trait criteria

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CONSUMER

• Price/ Value
• Consistency
• Holidays
• Taste/ Flavor
• Safety/ Health

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PACKER

• Dressing Percent
• Quality Grade
• Yield Grade

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FEEDER

• Health
• Gain
• Feed Efficiency

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Commercial or Purebred Producer

• Reproduction
• Maintenance Cost
• Growth
• Weaning
• Yearling

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ECONOMIC IMPORTANCE
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MEASURABLE TRAIT (Phenotype)

• GENETIC EFFECTS
• ½ GENETICS FROM Sire
• ½ GENETICS FROM Dam
• ENVIRONMENTAL EFFECTS
• WEATHER
• NUTRITION
• HEALTH
• Etc.

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Measures of Phenotype
P G E
Birth weights Weaning weights Yearling
weights Carcass Traits Reproductive
traits Adaptability
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Genetic Improvement p 12
P G E
Requires 1. Identification of animals 2.
Equipment to record trait measure 3. Record
Keeping System 4. Computer with Spreadsheet
is economical and recommended
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Genetic Evaluations

• Phenotypes and Pedigrees
• Objective convert data into genetic information
  for the purpose of selection

Separate genetic portion of phenotype from
environment.
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41 lbs
38 lbs

• 105 DAYS OLD
• ON FARM A
• BUCK
• 4 YR DOE

• 90 DAYS OLD
• ON FARM A
• BUCK
• 2 YR DOE

WHAT ARE THE KNOWN ENVIRONMENTAL EFFECTS?
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Known Environmental Effects
650
680

• AGE
• 15 DAYS 15 DAYS
• AGE OF DOE
• 2 YR OLD 4 YEAR OLD
• FARM
• SAME SAME

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Adjusted 90 day wt.formula
(Actual Wt - Birth wt)
X 90 doe age adj. birth wt
Age in days
Breed associations are calculating adjustments as
they accumulate data from the breeders
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Adjusted 90 day wt.
(38 7)
(41 8)
X 90 0 7
X 90 5 8
105 days
90 days
33.6 Lbs.
45.9 Lbs.
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(EPD)-Expected ProgenyDifference p13

• A prediction of the genetics an animal will pass
  on to his offspring, when compared to other
  animals within the breed
• Takes into account the actual measurements, all
  ancestral measurements and environment
• Not a perfect science, so use as a risk
  management tool

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College Football BCS
Purpose is to identify best college football teams
Source of Data AP ranking USA
Ranking Record Strength of schedule etc.
Ranking changes as more games are played
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National Sheep Improvement Project p42

• Breed summaries report
• EPDs.
• Expected Progeny Difference
• And Breeding Values

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Traits of Interest

• 60-day wt
• 120-day wt
• Yearling wt
• Greasy fleece wt
• Fiber diameter
• Number of lambs born

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National Goat Evaluation

• Breed Specific
• Breed summaries report
• EPDs.
• Expected Progeny Difference
• And Breeding Values

The American Boer Goat Association, American
Dairy Goat Association, National DHI Program
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Interpreting EPDs
Provide a prediction of future progeny
performance of one individual compared to future
progeny of another individual within a breed
for a specific trait. Allow one to compare or
rank the genetic superiority of individual
animals within a breed for a specific Trait. EPDs
are reported in the actual unit that the trait
is Measured (Lbs. for growth traits). They can
be positive or negative numbers
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Effective EPDs Examples

• Scrotal Circumference (SC)
• High SC males sire females with earlier Puberty
• Birth Weight (BW)
• Low BW males have more live offspring
• Average Daily Gain (ADG)
• Allows choice for replacements or sale of
  weanlings
• Carcass Merit (CM)
• Allows choice for direct or wholesale Marketing

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How do you use genetic tools in a selection
program ?
Start by using available information
Evaluate Breed Characteristics that Appear to fit
your marketing plan
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Average Breeding Values of SixDairy Goat Breeds
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Alpine LaMancha Nubian
You would expect 114 and 531 pounds less
milk From LaMancha and Nubian as compared to
Alpine
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Oberhasli Saanen Toggenburg
When compared to Alpine, you would expect 60 lbs
more Milk for Saanen, 476 lbs less milk from
Oberhasli and 18 lbs less milk from Toggenburg
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Meat Goat Industry

• Breed Associations are growing
• Members are sending data through membership
• Information is increasing
• Most selections must come from individual and
  herd data

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Meat Goat Industry

• Majority of information reports data on Spanish
  (brush), Boer, Kiko, Myotonic (fainting) and
  crossbreds
• This data provides ranges for comparison
• Emerging breed associations will help supply
  needed breeding values

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KIKO
Spanish
Common Meat Goat Breeds
BOER
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Boer Buck Performance Test(Langston Univ.
Okla. State Univ., 2004)
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Growth Performance(Langston Univ., 2003)
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Carcass Performance(Texas AM Univ, 1999)
Boer X Spanish
Spanish
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Mating Systems

• Purebreeding
• Outbreeding
• Inbreeding
• Crossbreeding

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Purebreeding p18

• Mating animals of common genetic heritage
• Registered (mostly)
• Focus on improving desirable traits
• Uniformity
• Breed Character

Kimm Farm
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Outbreeding

• Using Unrelated rams in purebred system
• Most common form of purebred breeding
• Less risky

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Inbreeding p19

• Mating animals that have one or more ancestors in
  common
• Results in increasing the number of gene pairs
  that are homozygous
• Fewer heterozygous gene pairs (duh!)
• Better chance of bringing out deleterious genes
• Linebreeding is inbreeding with focus on trying
  to replicate the genetics of a certain individual

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Crossbreeding p21

• Mating of animals of different breeds
• Preferably not just mixing, but planned
• Commercial lamb production typically driven by
  crossbreeding

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Grading up

• Repeated crossing of ewes and their female
  progeny sires of a target breed
• Start with females of any breed
• 1st cross - 50 of target
• 2nd cross - 75 of target
• 3rd cross 87.5
• 4th cross 93.75 (by now you are getting there)

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New Breed Formation

• Building a new breed by crossing specific other
  breeds
• Works better with sheep
• Corriedale, Columbia, Targhee, Montadale,
  Polypay, Katahdin and Coopworth are composites

Polypay Finnsheep, Targhee, Dorset and
Rambouillet
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Over 100 Different Breeds of Goats Worldwide.
Same for Sheep.
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Use Genetic Tools and Breeding Values
or EPDs When Available
Identify males that will contribute
to Improvement in economically important traits
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PERFORMANCE BENCHMARKS
What is the current level of herd
performance? What direction (if any) should the
herd move?
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Single Most Important Trait In The Goat or Sheep
Industry ??
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REPRODUCTION
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Measure of Production/ReproductionLbs weaned
/ dam exposed
crop weaned X avg. wn. Wt.
Prorates total lbs. weaned across all dams
maintained Best measure of productivity
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Fertility p52

• Heritability low (table 18)
• Lower and highly variable in ewe lambs
• The fact that sheep and goats are somewhat to
  highly seasonal breeders affects fertility

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Prolificacy

• Twinning
• Breed differences (each 1 of Finnsheep will
  increase prolificacy by 1)
• Keeping only females from twins will, over time,
  increase twinning

Romney x Finns
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Lbs. Weaned / Dam Exposed
Kidding
Avg. W.W.
Lbs. / dam
120 39 46.8
105 39 40.9
95 39 37.1
85 39 33.2
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Establish Benchmark of Production
Determine which traits need improvement Select
for that trait(s) BW birth weight WW weaning
weight SC scrotal circumference Adaptability
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Identify How to Use Different Sires for Different
Purposes
Produce Replacements Terminal Cross Males Birth
Ease Males Carcass Merit
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Use Trait Qualities
Heritability Heterosis Reproduction LOW
HIGH (fertility) Production MODERATE MODERATE
(growth) Product HIGH LOW (carcass)
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Preliminary Selection on Performance Then FOCUS
on
-Structural Soundness -Temperament -Scrotal
Circumference -etc.
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STRUCTURAL SOUNDNESSSkeletal design how well
the bonessupport the animals body

• Related to Longevity
• And Adaptability
• FEET
• LEGS

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Genes of Interest

• Booroola Merino
• Callipyge
• Scrapie
• Skin folds
• Spider
• Rectal prolapse
• Entropion

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Scrapie

• Infectious disease of sheep (goats?) caused by
  prions
• Invariably fatal attacks CNS Black faced
  breeds
• Spongiform encephalopathy - similar to Mad Cow
  and CJ or Kuru in humans
• Although caused by pathogenic organism, it only
  occurs in genetically susceptible animals
• At Codon 171, the presence of arginine (R) is
  associated with lower susceptibility while
  glutamine (Q) is associated with higher
  susceptibility

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Genetics of Scrapie SusceptibilityTable 21

• RR Low Susceptibility
• QR Low Susceptibility
• RR High Susceptibility
• Point in susceptible breeds, use RRs

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Color

• Complicated in sheep and goats
• 16 Loci involved with 15 genes per loci
• In sheep, black wool is an issue because it has
  little value in commercial trade while being very
  important to spinners

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Spider Syndrome

• Lethal recessive gene
• Lambs born severely deformed
• Gene test is now available

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Rectal Prolapse

• Most common with black-faced breeds and animals
  on full-feed
• Both genetic and environmental
• Proper tail removal can reduce incidence by up to
  50

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Entropion

• Eyelid inside out
• Genetics probably complicated and unknown
• Easy to treat, but hassle consider not keeping
  in breeding flock

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Whew!

• Genetics of sheep and goats is not easy, but it
  is important!
• Sheep and goats offer lots of material for making
  genetic progress
• It is difficult to get selection right every
  time, and mistakes are easy, but paying attention
  can allow dramatic progress