Variable/ trait :

1
Introuction to Genetic Parameter

• Variable/ trait
• 1. Coat color
• 2. Horn/hornless
• Animal power (work/ plough in paddy field)
• 4. Milk production, number of progeny

Genetic breed, genetic group,
linebred Environment feed, food, wind,
humidity, temperature, light, insect G x E
interaction breed-level of feed,
group-Temp.humid
2
GENETIC PARAMETER (PARAMETER GENETIK
) (heritabilitas/ heritability, ripitabilitas/
repeatability, korelasi genetik/ genetic
correlation)
What is heritability? Heritability can be defined
as the efficiency of transmission of superiority
(or inferiority) of a trait from parents to
offspring. It is usually expressed as a
percentage ranging from 0-100, or as a decimal
number ranging from 0 to 1.

• Trait
• - Quantitative traits (milk, meat, egg, work,
  wool, power, IQ etc)
• A matter of variance
• VP VG VE VGxE

P G E GxE Fenotipe genetik lingkungan
interaksi genetik-lingkungan
3
Traits that are 100 heritable If a
trait is 100 heritable, then the full expression
of the parents trait will be expressed in or by
the off-spring. A trait that is 100 heritable
would truly be a case of 'what you see is what
you get' as 100 of the trait or genotype will be
expressed in the animals phenotype, or the way
the animal looks. There are a great many other
traits that we take for granted as being 100
heritable. Under normal circumstances, many
physical traits such as number of fingers on a
human hand or the number of legs on the body of
cattle are 100 heritable. A person's phenotype
may be affected by the environment, for
example, if an arm is amputated as a result of an
accident, but the genes that an amputee carries
in his/her gametes mean that any offspring will
still be born with both arms. Other
physical traits, such as height in humans or
weight gain in cattle, are not 100 heritable. If
this were the case every brother or sister in any
species would be exactly the same height. The
heritability of height is less than 100.
4

• Heritability formula
• h2 VG/ VP
• V variance (d2)
• Data daily weight gain in cattle (kg)
• 0.6 6. 0.45
• 0.7 7. 0.55
• 0.8 8. 0.65 Mean ?
  Variance ?
• 0.5 9. 0.75
• 5. 0.75 10. 0.40
• Mean X 6.15/10 0.615 kg
• Variance s2 (0.6-0.615)2 (0.7-0.615)2
  (0.40-0.615)2/9
• 0.0189
• s 0.1375

5
Trait Heritability() Trait Heritability ()
Beef Cattle   Dairy Cattle  
Calving interval 10 Services per conception 5
Age at puberty 40 Birth weight 50
Scrotal circumference 50 Milk production 25
Birth weight 40 Fat production 25
Weaning weight 30 Protein 25
Post-weaning gain 45 Solids-not-fat 25
Yearling weight 40 Type score 30
Yearling hip frame size 40 Teat placement 20
Mature weight 50 Mastitis susceptibility 10
Carcass quality grade 40 Milking speed 30
Yield grade 30 Mature weight 35
Eye cancer 30 Excitability 25
 
6
Sheep   Poultry  
Number born 15 Age at sexual mature 35
Birth weight 30 Total egg production 25
Weaning weight 30 egg weight 40
Mature weight 40 Body weight 40
Post weaning gain 40 Shank length 45
Fleece weight 40 Egg hatchability 10
Fibre diameter 50 Livability 10
Face covering 55
Loin eye area 55 Swine
Carcass fat thickness 50 Litter size 10
Weight of retail cuts 50 Birth weight 5
Post weaning gain 30
Horses Backfat probe 40
Withers height 45 Carcass fat thickness 50
Pulling power 25 Weaning weight 15
Racing (log earnings) 50 Loin eye area 45
Trotters (log earnings) 40 Percent lean cuts 45
Jumping ( earnings) 20    
Dressage ( earnings) 20 Goats  
Cutting ability 5 Milk production 30
    Mohair production 20
7
REPEATABILITY (R)

• The ability to repeat expression of particular
  trait on the future/ next production period
• Correlation between (2 periods), or among (3 or
  more periods) measurements
• Examples
• Cow no. 1st lact. (100kg) 2nd
  lact. (100kg)
• 1 50
  55
• 2 60
  62
• 3 58
  59
• 4 62
  62.5
• 5 56
  58

R ?
8
GENETIC CORRELATION ( rG )

• Correlation between 2 traits on different
  generation
• - trait 1 on parent generation and trait 2
  on the next
• generation
• It is caused by
• - pleiotropic gene (1 gene influence 2/
  more traits)
• - linkage of genes (unreal genetic
  correlation)
• Examples
• - milk yield with fat (negatif)
• - weaning weight with post weaning gain
  (positif)
• - birth weight with litter size (in swine/
  negatif)

9
Some traits, such as hair color, are
determined by only a few genetic loci. The
inheritance of such traits is relatively easy to
predict, and the different phenotypes tend to
occur in qualitatively distinct states (such as
"black" and "red"). Other traits, usually called
quantitative traits, may be influenced by many
different genes, and the continuous variation
observed often has a relatively large
environmental component. Horn length in Texas
Longhorns is an example of a quantitative trait.
This article discusses the basics of selection
for quantitative traits, using horn length as an
example. Most traits of interest in Texas
Longhorns are controlled by many different
genetic loci, and many of these traits are also
influenced by the environment in which the animal
was raised and now lives. These traits typically
are expressed along a continuum, rather than as a
series of discrete states. For instance, the
amount of milk produced by a cow clearly is
influenced by her genetics, but it is also
influenced by environmental factors (such as how
much and what kind of food is available to the
cow). Moreover, cows vary along a continuum in
how much milk they produce. Such traits are
called quantitative traits.
Texas Longhorn cattle
10
Other trait the tail thickness of Fat Tailed
Sheep (Domba Ekor Gemuk) is quantitative trait,
so h2 of this trait can be measured. Homework
Search some kinds of quantitative traits on
internet, textbooks or journal
See you next week Wassalam