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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. - PowerPoint PPT Presentation
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Natural Selection
an organisms ability to SURVIVE and pass on its GENETIC information to its offspring.
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 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
Birth Weight = .40 Weaning Weight = .30 Multiple Births = 0.0 - 0.10 Dressing Percentage = .60
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.
Production of Sex Cells (Meiosis) 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.
OOGENESIS
1. occurs in OVARIES 2. DIFFERENT sized cells 3. ONE egg cell produced and
three POLAR bodies
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
Incomplete Dominance
The genes are neither dominant nor recessive, but are equals
Example -- Shorthorn Cattle
–WW=White
–RR=Red,
–RW=Roan
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.