Outcrossing, Linebreeding and Inbreeding in Andalusians

The breeder can approach his or her breeding theme in many different ways. He can breed like animals to like, similar family trees to similar, or unlike to unlike.

Outcrossing uses different, unrelated lines, to produce a foal. An outcross is a mating of two animals of the same breed that have no close relatives in common in the pedigree.

Often times, outcrossing is most successful when the outcross stallion is a strongly linebred individual. This ensures that the stallion will “stamp” his offspring with similar characteristics.

If, for example, you take a band of unrelated mares and outcross them to a linebred stallion, the resulting foals should resemble each other more than the mares do.

The ultimate goal then becomes the search to find a stallion that “nicks” with these first generation fillies.

Successful nicking occurs when the right combinations of genes are brought together through each parent and when these genes complement each other.

Outcrossing can be conducted in the United States by Andalusian breeders if and only if they breed US lines to Spanish lines. Or newly imported Spanish lines to other Spanish lines. The original US lines and some of the older Spanish lines are too closely related to be considered an outcross when bred to each other. Or if you bred a recently imported Spanish-line horse to a California-bred horse with older Mexican lines – that would be an outcross.

Linebreeding is built upon the principle of breeding like to like. The greatest danger in linebreeding is that all genes are intensified – the good AND the bad. In line-breeding, you, as a breeder, will find out what is good and what is bad about your program in a short amount of time.

Linebreeding is frequently practiced in Spain – mainly because of the small pool of horses from which to draw and the popularity of certain lines.

In the U.S., linebreeding is more common in the older American lines – and these were linebred because they were imported as linebred. Most breeders today have a variety of stock to choose from, and the close relatives of their horses are not linebred – but outcrosses.

Inbreeding is an intensified form of linebreeding. Inbreeding affords the quickest way of setting a specific trait within a breed. It also certaining INCREASES the numbers of undesirable breeding stock – when faults combine with faults. Inbreeding is most easily recognized when a half-sister is bred to a half-brother. Or a stallion is bred to his daughter’s offspring. Some breeders have put themselves in a rut with linebreeding because they have selected to breed their mares to a stallion that is closely related. And they choose not to outcross to other horses.

Seemingly, these breeders are trying to force the positive factors of their mares and stallions together and avoid what they see as negative traits in other sires. What they don’t realize is, that they are making things worse by not outcrossing. Half-brothers and siblings bred to each other, or stallions with the same female line as the mares you are breeding to, will double up on the positive traits as well as the bad traits. It’s true, you may get some super horses from inbreeding – but you will also get a large number of culls.

An example of an inbred horse is a mare that is bred to her half-brother.

The mare and stallion share the same sire line, but different dam lines.

This is somewhat acceptable inbreeding if the breeder has matched up the sire and dam correctly.

Another type of inbreeding is where the lines of both the mare and stallion converge into the same grandparents. This type of inbreeding is worse, where both the top and bottom are similar. Because there is no variety in the dam line, thus, the negative traits will tend to appear more often.