Genetics

1
Genetics

• By
• Mr. Gerbitz

2
What is Selection?

• Mating animals to produce certain characteristics
• Low Birth weight
• Heavier Weaning Weight
• Color
• Horned or Polled
• Temperment

3
What makes an animal they way that they are?

• Animals are the result of Feed, Health, and
  Inheritance (genetic material)
• Feed is fastest to correct
• Genetics last longest

4
What is Genetics?

• All body cells contain Blueprints with
  instructions as to how an animal will look or act
  etc.
• One Gene comes from each parent (pairs)
• Genes are divided into sections (Chromosomes)
  that carry genes
• Sex chromosomes male XY, female XX

5
What are Dominant Genes?

• Dominant Genes one gene overshadows the other
• Angus Cattle black is dominant, red is not (Bb)
• Hereford white face is dominant (Ww)
• Hampshire Hog white belt is dominant
• Horns are dominant (Pp)

6
What are Recessive Genes?

• The gene that is overshadowed by a dominant gene
• Recessive genes can only express themselves if
  both genes are recessive
• Polled vs Horned (Pp) (pp)
• Black wool vs white (Ww) (ww)
• Dwarfism vs normal size (dd)
• Albino

7
Punnet Square

• P horned
• p polled
• If a homozygous horned cow (PP) is mated to a
  homozygous polled bull (pp), what percent of the
  calves will be horned, polled?

8
Punnet Square
9
Punnet Square

• If a homozygous horned cow (PP) is mated to a
  heterozygous horned bull (Pp), what percent of
  the calves will be polled?

10
Punnet Square
11
What are Sex Linked Genes?

• Some recessive genes are attached to the X and Y
  chromosomes
• Humans Colorblindness and Baldness are on the X
  chromosomes
• In Men, traits expressed anytime present
• In Women, must have two recessives to show trait
• Children get baldness from mothers

12
Punnet Square What sex will the offspring be?
13
If Dad is bald, will you be bald?
14
Baldness is carried by the mother
15
What is Mom is bald?
16
What is Incomplete Dominance?

• If both genes express themselves
• Shorthorn Cattle Red male mated to a White
  female Roan calf
• RR WW RW

17
Punnet Square

• Shorthorn Cattle
• R Red
• W white
• RW roan
• If a red bull (RR) is mated to a white cow (WW),
  what color will the calves be?

18
Shorthorn Red X White
19
Punnet Square

• If a red bull (RR) is mated to a roan (RW) cow,
  what color will the calves be?

20
Shorthorn Red X Roan
21
What if Both Parents are Roan?
22
Undesirable Characteristics

• Dwarfism
• Monorchid only one testicle descends
• Cryptorchid no testicles descend
• Short ears tails

23
What is a Mutation?

• Dramatically different from what is expected
  genetically
• Horned calf from polled parents
• Loss of some or extra body parts
• Lethal Mutation causes death at birth
• Sublethal Mutation limits animals ability to
  grow to maturity
• Beneficial Mutation loss of tail in lambs

24
What is an Abnormality?

• Similar to a Mutation, only it is caused by
  something in the environment
• Siamese twins

25
What is Heritability?

• Chance that traits will be inherited
• Low multiple births, fat covering
• Medium birth wt, wean wt, milk, wool grade,
  carcass wt, rate of gain
• High Loin eye area, fleece length quality

26
Heritability

• Currently have ewes that wean 70 lb lambs
• Want to raise weaning wt to 110 lbs
• Select a ram with a wean wt of 110 lbs
• Heritability of weaning wt is 30
• What can you expect new lamb crop to weigh at
  weaning?

27
Heritability

• What is the difference in current weaning wt and
  that of the new ram?
• 110 - 70 40 lbs
• Heritability x difference
• 30 x 40 12 lbs
• Can expect a gain in weaning wt of 12 lbs
• 70 lbs 12 lbs 82 lbs

28
Mating Systems

• Random Mating all males have an equal
  opportunity to mate with all females
• Outcrossing mating purebreds with unrelated
  purebreds
• Inbreeding mating related animals
• Linebreeding parents mated to offspring
• Crossbreeding mating animals of same species but
  different breeds

29
What is Hybrid Vigor?

• Offspring will outperform either of the parents
• Corn Breed A yields 100 bu/acre
• Corn Breed B yields 100 bu/acre
• Crossbreed A B yields corn that yields 200
  bu/acre
• Vigor only expressed in crossbreeding
• Donkey mated to a horse Mule
• mule is sterile

30
What are Exotics?

• Animals not common to United States
• Difficult to define today
• New breeds are exotics

31
Genetic Terms

• Genotype genetic makeup (Bb)
• Phenotype physical appearance (Black)
• Heterosis Genes are different, Dominant
  Recessive (Bb)
• Homozygous both genes are the same (BB or bb)

32
(No Transcript)