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F.W.C. Neser
Animal breeding may be seen as the
optimal exploitation of the species
biological VARIATION
Ollivier (2000)
10cm vs 2m
159kg
vs
1kg
Thumbeline (42cm) vs Clydesdale (2m+)
You usually get what
you select for – but
not always
Sometimes the
unexpected happens
The breeding of animals that are more closely
related than the average of the population
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Increase homosigosity
Decrease variation
Decrease in performance, especially in fertility
and survivability
Affects polygenic traits because of inbreeding
depression
Genetic defects least of the problems
Linebreeding
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Genetic diversity can be defined as the
variation of genes and genotypes present in a
population, and provide a basis of adaptive
and evolutionary processes (Frankham et al.,
2002)
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Tankwa goats
Climate change
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Most endangered species went through
genetic bottleneck
Limited genetic variation within specie.
Any inbreeding or wrong mating practices will
destroy the variation that is left
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Create genetic lines within population
Lines should be manage as one population
Sires should be rotated between lines using as
specific order
This way inbreeding will be limited and new
diversity can be created
Recordkeeping
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Indekse
Blup – Teelwaardes
 Groter akkuraatheid
 Komplekse Modelle
 Seleksie vordering
Genetic trends for milk production in
the SA Holstein and Jersey population
200
0
-200
-400
-600
-800
-1000
1983
1985
1987
1989
1991
1993
Holstein
1995
Jersey
1997
1999
2001
2003
2005
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Seleksiedoelwitte
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Telers geen doelwitte
Teveel produksie te min fiksheid
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Inteling
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VSA -3.7 milj Holsteins
Effektiewe populasie
grootte 60 diere
• Jersey’s 38 diere
Inbreeding
USA average; - F = 5.85%
(2012)
1910
1930
1950
1970
1990
2010
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Fiksheid = NATUURLIKE SELEKSIE:
 Oorlewing
 Vrugbaarheid
Fiksheid dui op die relatiewe vermoë van
draers van ‘n spesifieke genotiepe om
hulle gene na die genepoel van die
volgende generasie oor te dra. Dit word
die aanpassingswaarde of die fiksheid in
die Darwin sin, van ‘n genotiepe genoem
(Dobzhnsky, 1959)
The heritability of fitness traits are usually
low and will be severly influence by
inbreeding
depression
and
heterosis
(Bourdon, 1997)
+ GENES FOR FITNESS
INTENSIVE SYSTEMS
NATURAL PASTURES
Selection for growth under
different conditions
Environmental limit
No limit on size
Environment limit size
Natural conditions
Artificial conditions
This is where an animal excels in one environment
but fail to perform in a second environment, while
another animal may excels in the second but fail to
perform in the first
Genotype for:
High appetite
Large Frame
P
r
o
d
u
c
t
i
v
i
t
y
High heat production
Genotype for:
Optimum
Low appetite
Small Frame
Low heat production
Unfavourable
No genotype, no matter how versatile,
is equally efficient in all
environments - Dobzhansky (1951)
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Alle diere is ewe vrugbaar
Vrugbaarheid kan nie geneties verbeter word
nie
Voer jou diere vrugbaar
MINDER VRUGBAAR
NIE GEKALF
BOGEMIDDELD
VRUGBAAR
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Eers net kwaliteits eienskappe
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Produksie eienskappe
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Vleissagtheid
Marmering
Voeromsetting
Vrugbaarheid
Groei
Melkproduksie
Wolproduksie/Veseldikte
Skape – 753 QTL’s, 212 eienskappe
Beeste – 6 305 QTL’s,
416 eienskappe
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Nie die “Magic bullet” nie
Hoofgeen verklaar tot 30% van σa2
Meeste QTL’s verklaar baie min –
minder as 1% van die σa2
Belangrikste eienskappe word deur
baie gene beinvloed
Omgewing skakel gene aan of af
Patentereg – groot maatskappye
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DNA Fingerprinting:
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Parentage verification
Microsatellites & SNP:
Inbreeding
 Heterozygosity and genetic variation
 Specie verification
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Whole genome sequencing
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Genetic variation
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Limit inbreeding
Maintain genetic diversity
Work with the environment
Recordkeeping