Obj discuss reproductive management terms used in the animal science industry
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Obj : Discuss reproductive management terms used in the animal science industry. . Genetics. 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 . Artificial Selection .

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Obj: Discuss reproductive management terms used in the animal science industry.


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

Artificial Selection

  • HUMANS control which organisms pass their GENETIC information (reproduce)

Phenotype VS. Genotype

  • Observable PHYSICAL characteristic


  • An organism’s GENETIC code (genes)

    Genotype=BB or Bb

    (Pattern of letters representing the genes for color)



Terms in Genetics

  • Genes: Factor that control traits

  • Alleles: Different forms of genes

    • Paired (AA or Aa) & represented by a letter

Terms in Genetics

  • Adaptability: The ability of a BREED to become SUITABLE to conditions

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,

Terms in Genetics

  • Species: a group of similar organisms that can produce fertile offspring



Terms in Genetics

  • Breed: animals having a common ORIGIN and CHARACTERISTICS different from animals within the same SPECIES


Quarter Horse






Terms in Genetics

  • Purebred

    • Individuals within a BREED

    • Must have all of the required CHARACTERISTICS

    • Recorded PEDIGREE

Terms in Genetics

  • Dominant alleles

    • Represented by capital letters

    • This trait is the one expressed

  • Recessive alleles

    • Represented in lower case letters

    • Only expressed if both parents donate recessive genes for a trait

Terms in Genetics

  • Homozygous: Alleles express the same trait type

    • (BB dominate) OR (bb recessive)

  • Heterozygous: Two different alleles for the same trait (Bb)

Punnet Square

  • A method of calculating the chances of inheriting a specific trait



  • Holstein Cattle

  • Black & White

  • Bb

  • Red & White

  • bb



Your Turn!

  • Solve the genetic problems using a Punnet Square

Breeding Systems

Breeding Systems

How to design a breeding system:

  • Set Goals

  • Choose measurable traits

  • Select parents according to goals

Breeding Systems

Traits to breed for:


Coat Color

Weaning weight


Speed Index

# Born Alive

Birth Weight

Breeding Systems

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.

Breeding Systems


  • Breed only animals that are purebred with registration papers

  • Goal: To produce high quality animals to sell as breeding stock

Breeding Systems

Grading Up

  • 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 and SAVE $$

    Most common in the livestock industry!!!

Breeding Systems


  • 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: crossbred offspring exceeds the average of the two parental breeds

Breeding Systems


  • 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

Breeding Systems


  • 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 expressed

    Deleterious gene: Could cause undesirable effects on an individual’s viability, productivity and/or economic value

Examples of Deleterious Genes

“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

Breeding Systems

Line Breeding

  • 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

Create Your Own Breed

  • Every breed of animal that we are familiar with today was once developed through generations of selective breeding to isolate specific traits unique to the breed.

  • You will now choose traits you like in a certain species to create you own new breed!

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