Strain breeding has been a staple of American Arabian breeding for some generations. Some breeders have based their entire programs on strain breeding, and breeding “pure in strain” (meaning horses with sire and dam both have the same strain), popularized by writings of Carl Raswan. The general concept of strain breeding is to breed Al Khamsa horses of a certain tail female line (strain) to AK horses of a certain other strain to get desired traits and features in the progeny. I have found that some horses follow true to form of what you would expect a horse of that strain would be, but others seem to be misnomers. So what’s going on?

The Bedouin concept of strains was used as a way to identify their horses, horses of other tribes, breeder descriptors, purity, provenance, and could be based on great stories of a war mare, endurance, and sometimes too, physical features. Bedouins however never practiced strain breeding historically, and have advised against it so as not to breed horses too tightly. Also, strain names have also been known to change when a horse is placed with a new family. The idea of strains for Bedouins is more cultural and fluid, and not tied to genetics or breeding practices.

I think it is unwise to think that basing breeding decisions primarily off of strain is a reliable method. It seemingly works sometimes, but is it all really just the strain/mtDNA powering through the rest of the pedigree? I find it over-confident to answer “yes” to that question. And perhaps, that is why the whole notion of strain breeding began to lose popularity amongst breeders when the desired traits of the paired strains did not deliver consistent results. I remember learning about strain breeding, and really being puzzled by it early on. My experiences in college biology classes certainly did not help with feeling confident about it. We learned about mitochondrial DNA inheritance, the mitochondria affecting cell metabolism, but could this really affect phenotype? Aside from being a hard vs easy keeper? My doubts began to set in…

If you look at strains of horses throughout a pedigree, there are many throughout the entirety of even just one. They have been crossed over with horses of other strains, and then again to different strains, then maybe back to the original depending on which ancestors you look at and how far back you look. I think the overarching goal is to find balance in the crosses, and to pick horses that balance out or improve upon features of each horse in the pairing. In my experience, I think utilizing “type” instead of “strain” (or relying on the mtDNA that a strain symbolizes) can yield the better balance between masculine to feminine, curvy to angular, course to refined that we are always chasing as breeders. Joe Ferriss eloquently (as per usual) gives insight and visuals into this notion/concept in the PDF attached at the end of this blog post. What has been credited to the genetics of the strain of a horse is really it’s type, of which the genetics are multifaceted.

The study of genetics is an emerging field when it comes to humans, let alone horses. It is proving to be scienfically unsound for breeders to solely rely on the perceived power of the strains/tail female lines/mtDNA. And what of unrecombinant Y-Chromosomal DNA? Is there no bearing on what might be inherited from the male contribution? More is being discovered about the genetics of y-chromosomes and how they affect gene expression. This ties in to my experience breeding Gassir tail-male horses, which I described in an article written in conjunction with Kate Rhodes of Van Alma Arabians. The sires of this male line are dominant producers when it comes to frame in their get, regardless of the strain. It is unmistakeable. An example that comes to mind is my stallion Baroud DHA who is a Dahman in strain but Koheilan in type (masuline), and produces more Koheilan-like type in his get. Perhaps some types are more dominant or recessive in certain areas than others, and this is why they have been thought to nick well with each other. However, attributing this solely to strain/mtDNA is oversimplified.

Although it is interesting when the strain breeding pairings do deliver as expected, but one has to wonder if this is sheer luck, chance, or other genetics within the pedigree coming into play, and I would bet on the latter.