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Horse Color Genetics

Equine Science Mr. Dieckhoff. Horse Color Genetics. Heredity Process of passing traits on to offspring Genes The basic unit of inheritance A DNA sequence at a specific location on a chromosome, occur in pairs. Basic Genetics. Human – 23 pairs (46 total) Chicken – 39 pairs (78 total)

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Horse Color Genetics

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  1. Equine Science Mr. Dieckhoff Horse Color Genetics

  2. Heredity • Process of passing traits on to offspring • Genes • The basic unit of inheritance • A DNA sequence at a specific location on a chromosome, occur in pairs Basic Genetics

  3. Human – 23 pairs (46 total) Chicken – 39 pairs (78 total) Cattle – 30 pairs (60 total) Sheep – 27 pairs (54 total) Swine – 19 pairs (38 total) Horse – 32 pairs (64 total) Donkey – 31 pairs (62 total) Mule – 63 total chromosomes

  4. Locus • Region of chromosome where particular gene is carried • Allele • Alternative forms of gene at locus • Genotype • Pair of alleles at given locus • Actual genetic makeup of individual terminology

  5. Homozygous • Same alleles at both loci • Heterozygous • Different alleles at both loci • Phenotype • Expression of alleles, what they look like terminology

  6. Complete Dominance • One allele “masks” expression of another • Ex: black coat color in angus cattle • BB = Black; bb = Red; Bb = Black • Partial or Incomplete Dominance • One allele does not completely “mask” expression of another allele • Ex: coat color in Shorthorn cattle • RR = Red; rr = White; Rr = Roan Modes of gene action

  7. If two roan shorthorns are bred, what are expected genotypes and phenotypes of their progeny? Punnett’s Square

  8. More than 10 loci involved • At any one locus, effects are generally due to dominance • Two types of skin pigmentation • Eumelanin (black or brown) • Pheomelanin (red or yellow) Qualitative Coat Color

  9. Can mask all other genes • W dominant to w • WW : lethal • Ww : true white • Pink skin and white hair • ww: not white • Color depends on other genes Gene W : White

  10. G dominant to g • G_: gray • All gray horses must have one gray parent • Flea-bitten grays are probablyGg • gg: not gray Gene G : Gray

  11. E dominant to e • E_: black hair (whole body or points) • Black, brown, bay, buckskin, etc. • ee: red hair • Sorrel, chestnut, palomino, etc. Gene E : Eumelanin (black hair)

  12. Controls distribution of black hair (E_) • E_A_ • Black points; bay • E_aa • Black body, black, brown • Eeaa / ee A_ • Chestnut, sorrel Gene A : Agouti (black Points)

  13. Controls dilution of red pigment • CC: full pigment • CCcr: yellow body • Bay = buckskin (E_A_CCcr) • Sorrel = palomino (eeCCcr) • Black = smoky black (E_aaCCcr) Gene C : Cream Dilution

  14. Controls dilution of red pigment • CcrCcr dilutes any coat color • Pale cream with pink skin and blue eyes Gene C : cream dilution

  15. Cremello (eeCcrCcr) • Will always produce buckskins, palominos, or smoky blacks • Perlino (E_A_CcrCcr) • Will always produce buckskins, palominos, or smoky blacks • Smoky Cream (E_aaCcrCcr) Gene C : Cream Dilution

  16. Dilutes both black and red coat color, but not dark points • Characteristics • Darker points • Dorsal stripe • Shoulder stripe • Leg barrrings • D dominant to d Gene D : Dun Gene

  17. Black base coat • E_aaCCdd : black • E_aaCCD_: grulla / grullo • Bay base coat • E_A_CCdd: bay • E_A_CCD_: bay dun or buckskin dun • Chestnut base coat • eeCCdd: chestnut • eeCCD_: red dun Gene D : Dun Dilution

  18. Rn is dominant to rn • Rn__: roan • rnrn: non roan • Must have at least one roan parent Gene Rn: Roan

  19. Dominant Gene • Must have at least one Champagne parent • Controls dilution of hair from black to brown and red to gold • Skin is lavender and speckles with age • Eye are amber Gene ch : Champagne Dilution

  20. Chestnut base coat • eeNN: chestnut • eeCh_: “gold” often with flaxen mane & tail • Bay base coat • E_A_NN: bay • E_A_Ch_: “amber”; tan with black points • Black base coat • E_aaNN: black • E_aaCh_: “classic”; darker tan with brown points Gene Ch : Champagne Dilution

  21. Dominant gene • Must have one silver parent • Controls dilution of black pigment • NN: full pigment • NZ or ZZ: • Sorrel: no effect • Bay: lightened pigment on lower legs and flaxen mane and tail • Black: chocolate with flaxen mane and tail Gene Z : Silver dilution

  22. Formerly “Barlink Dilution” • Recessive gene • Only seen in chestnuts • Can interact with Cream • Chestnut base coat • eeNN or NPrl: chestnut • eePrlPrl: pale apricot color of body, mane, and tail Gene Prl : Pearl Dilution

  23. http://www.animalgenetics.us/CCalculator1.asp http://www.vgl.ucdavis.edu/services/coatcolor.php Color calculator

  24. Determine the color patterns of the following horses: wwggeeaa CC ddrnrnNPrl WwGgEeaaCCcrddrnrn NN wwggEeAa CC ddrnrn NN wwggEeaa CC Ddrnrn NN wwgg EE AA CC ddrnrn ZZ wwggeeaaCcrCcrddrnrn NN wwggeeaa CC DdRnRn NN Application (21 Points, 3 ptsea)

  25. Chestnut or sorrel White Bay Gurlla / Grullo Chocolate with flaxen mane & tail Palomino or Cremello Red Roan Dun Answers (21 Points, 3 ptsea)

  26. wwggeeaaCcrCcrddrnrn NN wwGgEa CC DdRnrn ZZ wwggeeaa CC DdrnrnPrlPrl Quiz (9 Points)

  27. Buckskin, Palomino, or Smokey Black Flea Bitten Gray Chestnut with apricot body, mane, tail Answers

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