Genes
This presentation is the property of its rightful owner.
Sponsored Links
1 / 26

Genes PowerPoint PPT Presentation


  • 92 Views
  • Uploaded on
  • Presentation posted in: General

Genes. Located on chromosomes Thousands found in each animal Control inherited characteristics Carcass traits Growth rate Feed efficiency Two types of inherited traits Dominant Recessive. Genes. Dominant gene Hides the effect of another gene Polled condition in cattle is dominant

Download Presentation

Genes

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Genes

Genes

  • Located on chromosomes

  • Thousands found in each animal

  • Control inherited characteristics

    • Carcass traits

    • Growth rate

    • Feed efficiency

  • Two types of inherited traits

    • Dominant

    • Recessive


Genes1

Genes

  • Dominant gene

    • Hides the effect of another gene

    • Polled condition in cattle is dominant

    • The gene is represented by a capital letter

  • Recessive

    • Gene that is hidden by another

    • The gene is represented by a lower case letter


Genes2

Genes

Example:

The dominant gene is written- P

The recessive gene is written-p

P= Polled

p= horned


Homozygous and heterozygous

Homozygous and Heterozygous

  • Homozygous gene pair

    • Carries two genes for a trait

    • Polled cow might carry the gene PP

  • Heterozygous (or hybrid)

    • Carries two different genes that affect a trait

    • Polled cows might carry a recessive gene with the dominant Pp


Punnett square

Punnett Square

P= Polled

p= horned

Example:

  • Two polled cattle that are homozygous for the polled trait

Polled Dam

Polled Sire


Punnett square1

Punnett Square

N= Normal size

n= Dwarfism

Example:

  • Normal size in cattle is dominant to dwarfism

Normal Dam

Sire Carrier


Punnett square2

Punnett Square

N= Normal size

n= Dwarfism

Example:

  • What if both parents are carriers for a trait or disorder?

Normal Dam

Sire Carrier

Result: one out of every four births could result in a dwarf animal (1:2:1)


Monohybrid cross

Monohybrid Cross

  • A monohybrid cross is an estimation of a predicted outcome for a single trait.

  • If a homozygous horned cow (pp) is bred with a heterozygous polled bull (Pp), what percent of the calves will be polled?


Dihybrid cross

Dihybrid Cross

  • A dihybrid cross is a estimation of a predicted outcome for two traits.

  • What results if an Angus bull that is homozygous black and polled (BBPP) is bred with a red shorthorn cow which is homozygous red and horned (bbpp).

  • The bull BBPP can be simplified to BP (black & polled is the only possible contribution for the bull).

  • The cow bbpp can be simplified to bp (red & horned is the only possible contribution for the cow).


Dihybrid cross1

Dihybrid Cross

Black = 100%

Polled = 100%

Horned = 0%


Dihybrid cross2

Dihybrid Cross

  • Now if two of the offspring which are heterozygous for black/red and polled/horned (BbPp) are mated.

  • How do you do a Punnett square for two heterozyous animals?

  • Use all possible gene combinations.

  • Both the bull and cow are BbPp.

  • What are the possible contributions?

  • BP, Bp, bP, bp for both animals. (4 x 4 grid)


Dihybrid cross3

Dihybrid Cross


Dihybrid cross4

Dihybrid Cross

  • Black Polled = 9 out of 16 or 56.25%

  • Black Horned = 3 out of 16 or 18.75%

  • Red Polled = 3 out of 16 or 18.75%

  • Red Horned = 1 out of 16 or 6.25%


Dihybrid cross5

Dihybrid Cross

  • If a heterozygous bull (BbPp) is mated to a homozygous cow (BBPP).

  • What are the outcomes?


Dihybrid cross6

Dihybrid Cross


Dihybrid cross7

Dihybrid Cross

  • If a (BbPp) bull is mated to a (BBPp) cow.

  • what are the outcomes?


Dihybrid cross8

Dihybrid Cross


Assignment

Assignment

Complete a Punnett Square for two animals that are heterozygous for two traits:

  • Polled=P

  • Black= B

    (Alternatives are horned and red)

Dam

Sire


Genes

Practice

Black is dominant (B), and red is recessive (b). "Predict the offspring from the cross of a red bull and a black cow if the black cow's mother was red".


Genes

First things first: the only way for the red bull to be red (the recessive trait) is if it's genotype is homozygous recessive (2 little letters), so the red bull is "bb". Now, the black cow's genotype could be either "BB" or "Bb". If its mommy was red (bb), then this black cow MUST have inherited a little "b" from its mommy. So the black one in our cross is "Bb" (not "BB"), and our cattle cross is: Bb x bb. 


Heritability

Heritability

  • Objective:

    • Discuss hertability estimates for beef and swine


Heritability1

Heritability

  • Estimated the likelihood of a trait being passes on from the parent to the offspring

    • Low heritability

      • slow herd improvement

    • High heritability

      • faster improvement


Heritability2

Heritability

  • Swine rates are usually lower than cattle

  • Heritiability for carcass traits are higher than reproductive traits

  • Estimates vary from 0 to 70%


Genes

Heritability Estimates - cattle

Trait% Heritable

Number Born5

Weaning Wight30

Yeild Grade30

Carcass Grade35

Yearling Weight40

Scrotal Circumference50

Retail Yeild60

Rib Eye Area 70


Genes

Heritability Estimates - Swine

Trait% Heritable

Litter Size10

Weaning Wight (3 wks)15

Birth Weight20

Feed Efficiency30

Carcass length50


Genes

Heritability Estimates - Sheep

Trait% Heritable

Number Born13

Weaning Wight 30

Birth Weight30

Feed Efficiency20

Carcass (percent lean)35


  • Login