Genetics
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Genetics. What is Selection?. Mating animals to produce certain characteristics Low Birthweight Heavier Weaning Weight Color Horned or Polled Temperment. What makes an animal they way that they are?. Animals are the result of Feed, Health, and Inheritance (genetic material)

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Genetics

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What is selection
What is Selection?

  • Mating animals to produce certain characteristics

  • Low Birthweight

  • Heavier Weaning Weight

  • Color

  • Horned or Polled

  • Temperment


What makes an animal they way that they are
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


What is genetics
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


What are dominant genes
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)


What are recessive genes
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


Punnet square
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?



Punnet square2
Punnet Square

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



What are sex linked genes
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





What if mom is bald
What if Mom is bald?


What is incomplete dominance
What is Incomplete Dominance?

  • If both genes express themselves

  • Shorthorn Cattle: Red male mated to a White female = Roan calf

  • RR + WW = RW


Punnet square4
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?



Punnet square5
Punnet Square

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




Undesirable characteristics
Undesirable Characteristics

  • Dwarfism

  • Monorchid = only one testicle descends

  • Cryptorchid = no testicles descend

  • Short ears & tails


What is a mutation
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


What is an abnormality
What is an Abnormality?

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

  • Siamese twins


What is heritability
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


Heritability
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?


Heritability1
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


Mating systems
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


What is hybrid vigor
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


What are exotics
What are Exotics?

  • Animals not common to United States

  • Difficult to define today

  • New breeds are exotics


Genetic terms
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)


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