1. Genetics

2. Genetics Terms Heterozygous = two different types of genes (Bb)
Homozygous = two similar genes (BB)
Dominant Gene = trait overpowers others
Recessive Gene = must be accompanied with another recessive gene to express trait
Incomplete Dominance = both traits express themselves

3. Genetic Terms Genotype - genetic makeup (Bb)
Phenotype - physical appearance (Black)
Heterosis - Genes are different, Dominant & Recessive (Bb)

4. What is Selection? Mating animals to produce certain characteristics
Low Birth Weight
Heavier Weaning Weight
Color
Horned or Polled
Temperment

5. What makes an animal the way it is?
Animals are result of Feed, Health, and Inheritance (genetic material)
Feed is fastest to correct
Genetics last longest

6. What are 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

7. What are Dominant Genes?
Dominant Genes are traits that overpower other types of genes
Angus Cattle: black(B) color dominant, red (b) color recessive (Bb)
Hereford: white (W) face cattle dominant over colored (w) recessive (Ww)
Hampshire Hog: white (W) belt dominant, color (w) recessive (Ww)
Polled (P) cattle are dominant over horned (p) recessive (Pp)
Black (B) horses dominate, brown (b) recessive (Bb)

8. 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

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

10. Punnet Square p P Pp

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

12. Punnet Square P p P PP Pp P PP Pp

13. 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

14. Punnet Square: What sex will the offspring be?Y X XX XY X XX XY

15. If dad is bald, will you be bald?X Y B X
X X
X Y B X
X X XY B

16. Baldness is carried by the motherX Y X
X X
X Y B B B X
X X
X Y

17. What if mom is bald? X Y X
X X
X Y B B B X
X X
X Y B B B

18. What is Incomplete Dominance?
If both genes express themselves
Shorthorn Cattle: Red male mated to a White female = Roan calf
RR + WW = RW

19. 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?

20. Shorthorn: Red X White R R RW RW W W RW RW

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

22. Shorthorn: Red X Roan R R R RR RR W RW RW

23. What if Both Parents are Roan?RR RW W RW WW

24. Undesirable Characteristics
Dwarfism
Monorchid = only one testicle descends
Cryptorchid = no testicles descend
Short ears & tails

25. 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

26. What is an Abnormality?
Similar to a Mutation, only it is caused by something in the environment
Siamese twins

27. 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

28. 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?

29. Heritability
What is the difference in current weaning wt and that of the new ram?
= 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

30. 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

31. Crossbreeding mating of animals of different breeds
can increase productivity
produce animals with combination of traits
foundation stock for new breeds
introduce new genes quicker than in purebreds

32. What is Hybrid Vigor?
Offspring will out-perform either of the parents, also know as heterosis.
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

33. What are Exotics? Animals not common to United States
Difficult to define today
New breeds are exotics