Genetics Crash Course
LINEBREEDING
Is a form of inbreeding, an attempt to concentrate genes of a specific family line while maintaining the percentage of inbreeding where performance is not adversely affected. Linebreeding is a horse with common ancestors with a coefficient greater than 1.80% but less than 3.33%, which would give the animal less than 1 matched pair of chromosomes. A coefficient less than 1.80% is considered a hybrid.

INBREEDING
Relates to the number of times one or more comon ancestor(s) appear in a pedigree. The more times those specific ancestors appear on both the sire and the dam's side of the pedigree, the higher the inbreeding percentage.

Inbreeding is defined as an animal having an inbreeding coefficient of 3.33% or higher (which is the equivalent of a 3x3 match) and which gives the subject animal one or more matched pairs of chromosomes.

CROSSBREEDING
Crossing individuals from two different breeds, such as Quarter Horses and Thoroughbreds.

HYBRID VIGOR
Hybrid Vigor is the extra vitality observed when no defective genes are expressed and allows an individual to exhibit added vigor, size, speed, over that of the parents.

HOMOZYGOSITY
The number of matched chromosome pairs out of (32). The higher this number, the more likely the animal will be able to reproduce itself.

RULE OF THUMB - HYBRIDS PERFORM AND BREED DOWN, INBREDS BREED UP!

TO PRODUCE RUNNERS
Use an inbred (Purebred)stallion on Hybrid Mares.

INHERITED SPEED is 40% from breeding, 60% from environment

DOMINO was fastest inbred thoroughbred, he was inbred to Lexington.

PREPOTENT SIRES
The ability of a stallion or mare to consistently stamp or mark foals wth desirable traits. Three Bars first Thoroughbred inducted into the Quarter Horse Hall of Fame. Three Bars was Prepotent, consistently produced runners with Speed Indexes of 80+. Top Deck get - 63% were Race ROM, average today is 25%. Top Deck was line bred to Domino and inbred to Man O War.

ADDITIVE GENE ACTION

10% of a horse's genes is the minimum needed of a particular line to affect race performance.

20% of a horse's genes is needed to produce a major significant influence in offspring's performance.
    LEADING BREEDERS in the AQHA's past had three common demoninators:
  • Incorporate significant levels of the Domino line through Three Bars or Top Deck.
  • Inbreeding is practiced with selection.
  • Outcrossing their inbred horses to produce Hybrid runners.
BREEDING DECISIONS
Don't let emotions factor your decision on your breeding program. The Progressive breeder of tomorrow will follow a plan, they will engineer every mating they make, so that, each and every performer or breeder possesses superior math parameters above that of the average.

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