Are there any horse cross breeding calculators online?

Answer 1

Cross breeding is the intentional mixing of two distinctly different breeds or types of horses with the intent of producing a horse with the most desirable characteristics of

both parents or of the parent stocks.

A quick look at the internet reveals no horse specific calculators of the type in which you are interested. Most of the cattle crossbreeding calculators are oriented toward

milk, meat production that is designed to promote the benefits of breed specific crosses. (Just because I didn't find one doesn't mean it's not out there somewhere.)

The initial F1 cross has 50% of the genetics of each parent.

Subsequent percentages of blood now hinge on how the resulting F1 individuals are

crossed to produce the next generation.

A cross breeding program that only wants to incorporate a single characteristic from the program is very straight forward. Multiple traits require much more

diligence and would quite difficult to calculate.

Pintabians would be a good example a single trait program, where the breeders wanted to ad a spotting pattern to their Arabian horses but otherwise retain all the

Arabian characteristics and eventually produce a genetically near 100% Arabian horse by blood.

If the desired spotting pattern is Tobiano (a dominant trait) the breeder(s) need to

select the method(s) of aquiring the desired trait. The breeder(s) can choose to find mares from the spotted breed for a stallion(s) and retain only the F1 foals that have the Tobiano gene. These foals will be 50% Arabian. (The other option is to use a stallion, hopefully Homozygous Tobiano, to produce all spotted F1 foals. This also maintains the female family genetics of the desired rootstock/mitochondrial DNA if this is deemed important).

The best choice for crossbreeding is a breed with the Tobiano spotting trait that is structurally similar and with considerable common ancestry to the Arabian horse.

Selection of the superior spotted F1 foals and exclusively breeding these individuals to purebred Arabians will yield an F2 generation that is 75% Arabian (by blood).

Again, if only superior spotted F2 foals are bred to purebred Arabians the F3 spotted foals will be 87.5% Arabian by blood.

Using the same technique the F4 generation will be 93.75% Arabian.

F5 96.88%

F6 98.44%

Of course, even though the ultimate goal is to have spotted Arabians, the purebred to

spotted scenario will not yield the ultimate Pintabian, which is a true breeding Tobiano that is genetically as close to 100% Arabian as possible. Waiting until the

F4, F5 or F6 generation to breed for a homozygous Tobiano using crossbred offspring is a considerable investment in both time and money. The choice to breed superior F3 individuals that can later be crossed back on purebred Arabians to achieve a "true" 99% plus Arabian would be more cost effective.