Transcript Animal Genetics

Animal Genetics
Natural Selection
 an
organisms ability to
SURVIVE and pass on its
GENETIC information to its
offspring.
Artificial Selection
 HUMAN
control over organisms
passing on their GENETIC
information.
Heredity

the POTENTIAL an organism
has to show certain TRAITS
due to its GENETIC information
Environment
 the
EXTERNAL conditions that
affect the traits and
PERFORMANCE of an animal
Environment vs. Heredity
 An
organism's traits and
performance are a sum total of
its ENVIRONMENT acting upon
its GENETIC information.
Environment vs. Heredity
 Some
TRAITS are influenced
more by an organism's
ENVIRONMENT than by its
GENETICS, while others are
influenced more by genetics.
Heritability
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The percentage that a trait is affected
by its genetic information is called
HERITABILITY.
A heritability factor of 0.0 means that a
trait is influenced very little by genetic
information
A heritability factor of 1.0 means that a
trait is influenced very little by the
environment.
Examples of Heritability
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Birth Weight = .40
Weaning Weight = .30
Multiple Births = 0.0 - 0.10
Dressing Percentage = .60
Adaptability
 The
ability of a BREED to
become SUITABLE to specific
environmental conditions
Type
a
group of ANIMALS that are
grouped together according to
the PRODUCTS they produce
 Examples -- Beef type cattle,
Dairy type cattle, Wool type
sheep, Mutton type sheep
Species
a
group of ORGANISMS that
have several common
CHARACTERISTICS that
differentiate them from others.
Scientific Names of Species
 Cattle:
Bos taurus, Bos indicus
 Sheep: Ovis aires
 Swine: Sui suidae
 Horse: Euquis caballus
 Chickens: Galus galus
Breed
 animals
having a common
ORIGIN and
CHARACTERISTICS that
distinguish them from other
groups within the same
SPECIES.
Purebred
 individuals
within a BREED.
They must have all of the
CHARACTERISTICS of the
breed and have a recorded
PEDIGREE.
Pedigree
a
record of an individual's
ANCESTRY.
Breeds of Cattle
Angus
Angus
Hereford
Charolais
Charolais
Brahman
Brahman
Shorthorn
Shorthorn
Simmental
Simmental
Salers
Salers
Texas Longhorn
Red Angus
Limousin
Belted Galloway
Beefmaster
Holstein-Friesian
Holstein-Friesian
Guernsey
Jersey
Breeds of Sheep
Rambouillet
Rambouillet
Columbia
Suffolk
Suffolk
Hampshire
Merino
Dorset
Lincoln
Breeds of Swine
Duroc
Hampshire
Chesterwhite
Yorkshire
Landrace
Production of Sex Cells
(Meiosis)
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1. SIMILAR events to mitosis
2. Occurs ONLY in the TESTES and
OVARIES to produce egg and sperm
cells.
3. REDUCES the NUMBER of
chromosomes to half the normal
number.
4. ONE replication followed by TWO cell
divisions.
Meiosis
FERTILIZATION
 the
union of the egg and sperm
nuclei
 restores the normal
chromosome number.
ZYGOTE
a
fertilized egg
SPERMATOGENESIS
 1.
occurs in TESTES
 2. EQUALLY sized cells
 3. FOUR sperm cells produced
Spermatogenesis
OOGENESIS
 1.
occurs in OVARIES
 2. DIFFERENT sized cells
 3. ONE egg cell produced and
three POLAR bodies
Oogenesis
Patterns of Inheritance
DOMINANT
 the
trait that SHOWS in a cross
between two true-breeding
parents
 Example in Cattle -- Black coat
color, polled
 Example in Sheep -- White wool
 Example in Swine -- Black hair
Recessive
 the
trait that is HIDDEN in a
cross between two individuals.
 Example in Cattle -- Red coat
color, horns, dwarfism
 Example in Sheep -- Black wool
 Example in Swine -- Red hair
PHENOTYPE
 the
OUTWARD appearance of
the organism
Genotype
 the
actual GENE MAKEUP of
an organism
Homozygous
 when
both of the genes (letters)
in the pair are the SAME
 Example -- TT or tt
Heterozygous
 when
both of the genes (letters)
in the pair are DIFFERENT
 Example -- Tt
Incomplete Dominance
 The
genes are neither dominant
nor recessive, but are equals
 Example -- Shorthorn Cattle
–WW=White
–RR=Red,
–RW=Roan
Types of Mating Systems
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Purebred
Inbreeding
Linebreeding
Outcrossing
Grading up
Crossbreeding
Hybrid vigor
 increased
performance of
offspring over that of the
parents when unrelated
individuals are mated.
 Heterosis
Performance Pedigrees
 summarizes
a particular
animal's own performance
records as well as records of
ancestors, siblings, and
progeny.
 Progeny = offspring
EPD
 EXPECTED
PROGENY
DIFFERENCE
 an INDICATION of the amount
of GENETIC merit that an
animal will pass on to its
offspring.
EPD example
a
bull with an EPD for weaning
weight of +25.0 pounds means
that the bull's offspring should
average 25.0 pounds more at
205 days of age than offspring
of a bull with an EPD for
weaning weight of 0.0 pounds.
EPD Abbreviations
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BW = Birth Weight
WW = Weaning Weight (205 days of
age)
YW = Yearling Weight (365 days of
age)
milk = maternal milking ability
expressed in pounds of calf weaned.