Transcript 00-Genetics PP

Genetics
in the Animal Industry
A.
B.
C.
D.
Describe 2 types of selection
Compare Phenotype and Genotype
Define Common Terms used in genetics
Describe the interrelationship between
genetics and the environment.
E. Demonstrate the use of a punnet square
F. Compare common breeding systems used
in the animal industry
What Do You Know?
• Get out a piece of paper
• You are going to write a letter to yourself. Take 3
minutes for each paragraph. Write the entire time.
DON’T STOP WRITING UNTIL TIME IS UP.
• In the first paragraph answer this question:
– What do you know about genetics?
• In the second paragraph answer this question:
– What do you think you know about genetics?
• Share…
• In the third paragraph answer this question:
– What don’t you know yet?
A.
Describe 2 types of selection
Natural Selection
–No human intervention
–Survival of the fittest
–Based on an organism’s ability to
SURVIVE and pass on its GENETIC
information to its offspring.
A.
Describe 2 types of selection
Artificial Selection
• HUMANS control which organisms
pass on their GENETIC information
(reproduce)
B. Compare Phenotype and Genotype
Phenotype
Genotype
•Observable physical •An organism’s
genetic code (genes)
characteristic
Phenotype= Black Genotype= BB or Bb
(a pattern of letters representing the genes for
color)
C. Define Common Terms used in genetics
Terms in Genetics
• Gene= Factor that control traits
• Alleles= Different forms of genes
–Paired (AA or Aa) & represented by a
letter
C. Define Common Terms used in genetics
Terms in Genetics
• Adaptability= The ability of a
BREED to become SUITABLE to
specific environmental
conditions
C. Define Common Terms used in genetics
Terms in Genetics
• 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
C. Define Common Terms used in genetics
Terms in Genetics
• Species= a group of similar
organisms that can produce fertile
offspring.
Canine
Equine
Terms in Genetics
• Breed= animals having a common
ORIGIN and CHARACTERISTICS
different from animals within the
same SPECIES.
Canine
Quarter
Horse
Irish Wolfhound
Clydesdale
Golden Retriever
Chihuahua
Equine Miniature Horse
Terms in Genetics
• Purebred=
–individuals within a BREED
–must have all of the required
CHARACTERISTICS
–recorded PEDIGREE.
C. Define Common Terms used in genetics
Terms in Genetics
• Dominant alleles=
–Represented by capital letters
–This trait is the one expressed
• Recessive alleles=
–Represented by lower case letters
–Only expressed if both parents
donate recessive genes for a trait
C. Define Common Terms used in genetics
Terms in Genetics
• Homozygous= Alleles express
same trait type
– (BB dominate) OR (bb recessive)
• Heterozygous= two different
alleles for the same trait (Bb)
D. Describe the interrelationship between genetics and the environment.
Heredity vs Environment
•
Heredity= the POTENTIAL an
animal has to show specific
TRAITS or performance due to its
GENETIC information
D. Describe the interrelationship between genetics and the environment.
Heredity vs Environment
• Environment= the EXTERNAL
conditions that affect the traits
and PERFORMANCE of an animal
D. Describe the interrelationship between genetics and the environment.
Heredity vs Environment
Environment
+
Genetics
Traits
&
Performance
=
D. Describe the interrelationship between genetics and the environment.
Heredity vs Environment
• Some TRAITS are influenced more by
an organism's ENVIRONMENT
• Other traits are influenced most by
GENETICS
Environment Genetics
D. Describe the interrelationship between genetics and the environment.
Heredity vs Environment
• HERITABILITY= The percentage a trait is
affected by its genetic information.
– A heritability factor of 0.0 = little influence
from genetic information.
– A heritability factor of 1.0= BIG influence
from genetic information.
D. Describe the interrelationship between genetics and the environment.
Heredity vs Environment
Examples of Heritability:
• Birth Weight = .40
• Weaning Weight = .30
• Multiple Births = 0.0 - 0.10
• Dressing Percentage = .60
E. Demonstrate the use of a punnet square
Punnet Square
A method of calculating the chances of
inheriting a specific trait
Holstein Cattle
• Black & white
B
b
Bb
• Red & White
bb
b
Bb
bb
Bb
bb
b
E. Demonstrate the use of a punnet square
Punnet Square
Suppose you have a Holstein dairy farm of
ALL black and white cows. You want some
red and white Holsteins. Is it possible???
B
B
B
b
b
b
Bb
Bb
b
b
Bb
Bb
Bb
bb
Bb
bb
F. Compare common breeding systems used in the animal industry
How to design a breeding system:
1.Set Goals
2.Choose measureable traits
3.Select parents according to goals
F. Compare common breeding systems used in the animal industry
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F. Compare common breeding systems used in the animal industry
How to measure traits
• Qualitative Traits:
– Controlled by SINGLE pair of genes
– Not altered by environment
– Example: Coat Color
• Quantitative Traits:
– Controlled by SEVERAL pair of genes
– Can be altered by environment
– Examples: Weight gain, growth rate, backfat
depth, etc.
F. Compare common breeding systems used in the animal industry
•Breed only animals that are purebred with
registration papers
• Goal: To produce high quality animals to
sell as breeding stock
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F. Compare common breeding systems used in the animal industry
• Breed purebred sires to commercial
females
• Replacement females are kept and bred
back to the purebred sire
• Goal: To produce progeny resembling the
purebred sire & Save money
Most common in the livestock industry!!
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F. Compare common breeding systems used in the animal industry
• The mating of animals of different breeds
• Goal: To take advantage of hybrid vigor
and hopefully have offspring inherit good
traits of both parents
hybrid vigor (heterosis) -- crossbred
offspring exceeds the average of the two
parental breeds
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F. Compare common breeding systems used in the animal industry
Increase of pound of calf
weaned per cow exposed
Cumulative Effects
25
20
15
23.3
10
5
0
8.5
0
Br eed A
Br eed A
Xbr eed AB
X
X
X
Br eed A
Br eed B
Br eed C
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F. Compare common breeding systems used in the animal industry
•mating of related individuals – sires and dams that
share at least one ancestor
•Necessary when creating new breeds or when you need
to isolate genes for chosen traits
•Goal: Isolate unique/rare genes and perpetuate them
Full Brother X Full Sister
Half Brother X Half Sister
.25 coefficient or 25% inbred
.125 coefficient or 12.5% inbred
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F. Compare common breeding systems used in the animal industry
•Increase uniformity of offspring
•Could result in the surfacing of deleterious genes
•Reduction in performance because what use to be hidden
by recessive genes is now being expressed
deleterious gene – could cause undesirable effects on an
individual’s viability, productivity and/or economic value
30
F. Compare common breeding systems used in the animal industry
“Lethal White” gene in Paints:
•Foals carried full term
•All white or mostly white
coats
•Look & Seem fine at birth
•BUT colon is non functioning.
They show symptoms of colic
and die within 48 hours.
•Gene is carried on the overo
color gene
•Recessive gene was
perpetuated as overo paints
were bred.
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F. Compare common breeding systems used in the animal industry
•A minor form of inbreeding with the attempt to keep a
relationship to a highly regarded ancestor
Elite Sire X Half Sisters
Son of Elite Sire X Daughter of above Females
Grandsire X Granddaughters
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Study for Test
•
•
•
•
•
Genotype vs Phenotype
Homozygous, heterozygous
Artificial vs natural selection
Breeding systems
Punnet squares
– Solve
– Ratio of phenotypes and genotypes
http://www.ksl.com/index.php?nid=218&ad=14464679&cat=105&lpid=&search=standard%20poodle
http://www.ksl.com/index.php?nid=218&ad=14368992&cat=105&lpid=&search=standard%20poodle
http://www.ksl.com/index.php?nid=218&ad=14466119&cat=105&lpid=&search=poodle
Bell Quiz
• Describe the difference between environment and
genetics
• Describe difference between Natural Selection and
artificial selection
• Give an example of a Homozygous dominant genotype
• Is it possible to get a red and white holstein calf from a
black and white cow?
• The trait of birth weight has a heritability factor of 0.6,
would it wise to try to improve your weaning weight
through genetics? What tool would you use to choose
sires that will improve weaning weight?
Bell Ringer
1. What is the difference between homozygous
and heterozygous?
2. Give an example of a homozygous and a
heterozygous genotype.
3. What is the difference between dominate
and recessive?
4. What types of letters are used to represent a
dominate vs a recessive genotype?
Bell Ringer
March 20, 2013
• Find the genotype and phenotype ratios and
percentages from the following crosses:
1. Black rabbits are dominate over white.
a) Mom = heterozygous black
b) Dad = homozygous white
a) How many rabbits will be show the recessive trait?
2. Curly hair is dominate over straight in
poodles.
a) Mom = homozygous curly
b) Dad = homozygous straight
a) How many poodles will show the recessive trait?