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Genetics

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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Genetics

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

  2. 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

  3. Artificial Selection • HUMANS control which organisms pass their GENETIC information (reproduce)

  4. Phenotype VS. Genotype • Observable PHYSICAL characteristic Phenotype=Black • An organism’s GENETIC code (genes) Genotype=BB or Bb (Pattern of letters representing the genes for color) PHENOTYPE GENOTYPE

  5. Terms in Genetics • Genes: Factor that control traits • Alleles: Different forms of genes • Paired (AA or Aa) & represented by a letter

  6. Terms in Genetics • Adaptability: The ability of a BREED to become SUITABLE to conditions

  7. 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,

  8. Terms in Genetics • Species: a group of similar organisms that can produce fertile offspring Canine Equine

  9. Terms in Genetics • Breed: animals having a common ORIGIN and CHARACTERISTICS different from animals within the same SPECIES Labrador Quarter Horse Chihuahua Clydesdale Australian Shepard Arabian

  10. Terms in Genetics • Purebred • Individuals within a BREED • Must have all of the required CHARACTERISTICS • Recorded PEDIGREE

  11. 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

  12. Terms in Genetics • Homozygous: Alleles express the same trait type • (BB dominate) OR (bb recessive) • Heterozygous: Two different alleles for the same trait (Bb)

  13. Punnet Square • A method of calculating the chances of inheriting a specific trait b B • Holstein Cattle • Black & White • Bb • Red & White • bb b b

  14. Your Turn! • Solve the genetic problems using a Punnet Square

  15. Breeding Systems

  16. Breeding Systems How to design a breeding system: • Set Goals • Choose measurable traits • Select parents according to goals

  17. Breeding Systems Traits to breed for: Milk Coat Color Weaning weight Height Speed Index # Born Alive Birth Weight

  18. 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.

  19. Breeding Systems Purebred • Breed only animals that are purebred with registration papers • Goal: To produce high quality animals to sell as breeding stock

  20. 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!!!

  21. Breeding Systems Crossbreeding • 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

  22. Breeding Systems Inbreeding • 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

  23. Breeding Systems Inbreeding • 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

  24. 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

  25. 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

  26. 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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